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1. Overview of the EUROfusion Tokamak Exploitation programme in support of ITER and DEMO

Author: E. Joffrin, M. Wischmeier, M. Baruzzo, A. Hakola, A. Kappatou, D. Keeling, B. Labit, E. Tsitrone, N. Vianello, the ASDEX Upgrade Team, JET Contributors, the MAST-U Team, the TCV Team, the WEST Team, the EUROfusion Tokamak Exploitation Team:, D. Abate, J. Adamek, M. Agostini, C. Albert, F.C.P. Albert Devasagayam, S. Aleiferis, E. Alessi, J. Alhage, S. Allan, J. Allcock, M. Alonzo, G. Anastasiou, E. Andersson Sunden, C. Angioni, Y. Anquetin, L. Appel, G.M. Apruzzese, M. Ariola, C. Arnas, J.F. Artaud, W. Arter, O. Asztalos, L. Aucone, M.H. Aumeunier, F. Auriemma, J. Ayllon, E. Aymerich, A. Baciero, F. Bagnato, L. Bähner, F. Bairaktaris, P. Balázs, L. Balbinot, I. Balboa, M. Balden, A. Balestri, M. Baquero Ruiz, T. Barberis, C. Barcellona, O. Bardsley, S. Benkadda, T. Bensadon, E. Bernard, M. Bernert, H. Betar, R. Bianchetti Morales, J. Bielecki, R. Bilato, P. Bilkova, W. Bin, G. Birkenmeier, R. Bisson, P. Blanchard, A. Bleasdale, V. Bobkov, A. Boboc, A. Bock, K. Bogar, P. Bohm, T. Bolzonella, F. Bombarda, N. Bonanomi, L. Boncagni, D. Bonfiglio, R. Bonifetto, M. Bonotto, D. Borodin, I. Borodkina, T.O.S.J. Bosman, C. Bourdelle, C. Bowman, S. Brezinsek, D. Brida, F. Brochard, R. Brunet, D. Brunetti, V. Bruno, R. Buchholz, J. Buermans, H. Bufferand, P. Buratti, A. Burckhart, J. Cai, R. Calado, J. Caloud, S. Cancelli, F. Cani, B. Cannas, M. Cappelli, S. Carcangiu, A. Cardinali, S. Carli, D. Carnevale, M. Carole, M. Carpita, D. Carralero, F. Caruggi, I.S. Carvalho, I. Casiraghi, A. Casolari, F.J. Casson, C. Castaldo, A. Cathey, F. Causa, J. Cavalier, M. Cavedon, J. Cazabonne, M. Cecconello, L. Ceelen, A. Celora, J. Cerovsky, C.D. Challis, R. Chandra, A. Chankin, B. Chapman, H. Chen, M. Chernyshova, A.G. Chiariello, P. Chmielewski, A. Chomiczewska, C. Cianfarani, G. Ciraolo, J. Citrin, F. Clairet, S. Coda, R. Coelho, J.W. Coenen, I.H. Coffey, C. Colandrea, L. Colas, S. Conroy, C. Contre, N.J. Conway, L. Cordaro, Y. Corre, D. Costa, S. Costea, D. Coster, X. Courtois, C. Cowley, T. Craciunescu, G. Croci, A.M. Croitoru, K. Crombe, D.J. Cruz Zabala, G. Cseh, T. Czarski, A. Da Ros, A. Dal Molin, M. Dalla Rosa, Y. Damizia, O. D’Arcangelo, P. David, M. De Angeli, E. De la Cal, E. De La Luna, G. De Tommasi, J. Decker, R. Dejarnac, D. Del Sarto, G. Derks, C. Desgranges, P. Devynck, S. Di Genova, L.E. di Grazia, A. Di Siena, M. Dicorato, M. Diez, M. Dimitrova, T. Dittmar, L. Dittrich, J.J. Domínguez Palacios Durán, P. Donnel, D. Douai, S. Dowson, S. Doyle, M. Dreval, P. Drews, L. Dubus, R. Dumont, D. Dunai, M. Dunne, A. Durif, F. Durodie, G. Durr Legoupil Nicoud, B. Duval, R. Dux, T. Eich, A. Ekedahl, S. Elmore, G. Ericsson, J. Eriksson, B. Eriksson, F. Eriksson, S. Ertmer, A. Escarguel, B. Esposito, T. Estrada, E. Fable, M. Faitsch, N. Fakhrayi Mofrad, A. Fanni, T. Farley, M. Farník, N. Fedorczak, F. Felici, X. Feng, J. Ferreira, D. Ferreira, N. Ferron, O. Fevrier, O. Ficker, A.R. Field, A. Figueiredo, N. Fil, D. Fiorucci, M. Firdaouss, R. Fischer, M. Fitzgerald, M. Flebbe, M. Fontana, J. Fontdecaba Climent, A. Frank, E. Fransson, L. Frassinetti, D. Frigione, S. Futatani, R. Futtersack, S. Gabriellini, D. Gadariya, D. Galassi, K. Galazka, J. Galdon, S. Galeani, D. Gallart, A. Gallo, C. Galperti, M. Gambrioli, S. Garavaglia, J. Garcia, M. Garcia Munoz, J. Gardarein, L. Garzotti, J. Gaspar, R. Gatto, P. Gaudio, M. Gelfusa, J. Gerardin, S.N. Gerasimov, R. Gerru Miguelanez, G. Gervasini, Z. Ghani, F.M. Ghezzi, G. Ghillardi, L. Giannone, S. Gibson, L. Gil, A. Gillgren, E. Giovannozzi, C. Giroud, G. Giruzzi, T. Gleiter, M. Gobbin, V. Goloborodko, A. González Ganzábal, T. Goodman, V. Gopakumar, G. Gorini, T. Görler, S. Gorno, G. Granucci, D. Greenhouse, G. Grenfell, M. Griener, W. Gromelski, M. Groth, O. Grover, M. Gruca, A. Gude, C. Guillemaut, R. Guirlet, J. Gunn, T. Gyergyek, L. Hagg, J. Hall, C.J. Ham, M. Hamed, T. Happel, G. Harrer, J. Harrison, D. Harting, N.C. Hawkes, P. Heinrich, S. Henderson, P. Hennequin, R. Henriques, S. Heuraux, J. Hidalgo Salaverri, J. Hillairet, J.C. Hillesheim, A. Hjalmarsson, A. Ho, J. Hobirk, E. Hodille, M. Hölzl, M. Hoppe, J. Horacek, N. Horsten, L. Horvath, M. Houry, K. Hromasova, J. Huang, Z. Huang, A. Huber, E. Huett, P. Huynh, A. Iantchenko, M. Imrisek, P. Innocente, C. Ionita Schrittwieser, H. Isliker, P. Ivanova, I. Ivanova Stanik, M. Jablczynska, S. Jachmich, A.S. Jacobsen, P. Jacquet, A. Jansen van Vuuren, A. Jardin, H. Järleblad, A. Järvinen, F. Jaulmes, T. Jensen, I. Jepu, S. Jessica, T. Johnson, A. Juven, J. Kalis, J. Karhunen, R. Karimov, A.N. Karpushov, S. Kasilov, Y. Kazakov, P.V. Kazantzidis, W. Kernbichler, HT. Kim, D.B. King, V.G. Kiptily, A. Kirjasuo, K.K. Kirov, A. Kirschner, A. Kit, T. Kiviniemi, F. Kjær, E. Klinkby, A. Knieps, U. Knoche, M. Kochan, F. Köchl, G. Kocsis, J.T.W. Koenders, L. Kogan, Y. Kolesnichenko, Y. Kominis, M. Komm, M. Kong, B. Kool, S.B. Korsholm, D. Kos, M. Koubiti, J. Kovacic, Y. Kovtun, E. Kowalska Strzeciwilk, K. Koziol, M. Kozulia, A. Krämer Flecken, A. Kreter, K. Krieger, U. Kruezi, O. Krutkin, O. Kudlacek, U. Kumar, H. Kumpulainen, M.H. Kushoro, R. Kwiatkowski, M. La Matina, M. Lacquaniti, L. Laguardia, P. Lainer, P. Lang, M. Larsen, E. Laszynska, K.D. Lawson, A. Lazaros, E. Lazzaro, M.Y.K. Lee, S. Leerink, M. Lehnen, M. Lennholm, E. Lerche, Y. Liang, A. Lier, J. Likonen, O. Linder, B. Lipschultz, A. Listopad, X. Litaudon, E. Litherland Smith, D. Liuzza, T. Loarer, P.J. Lomas, J. Lombardo, N. Lonigro, R. Lorenzini, C. Lowry, T. Luda di Cortemiglia, A. Ludvig Osipov, T. Lunt, V. Lutsenko, E. Macusova, R. Mäenpää, P. Maget, C.F. Maggi, J. Mailloux, S. Makarov, K. Malinowski, P. Manas, A. Mancini, D. Mancini, P. Mantica, M. Mantsinen, J. Manyer, M. Maraschek, G. Marceca, G. Marcer, C. Marchetto, S. Marchioni, A. Mariani, M. Marin, M. Markl, T. Markovic, D. Marocco, S. Marsden, L. Martellucci, P. Martin, C. Martin, F. Martinelli, L. Martinelli, J.R. Martin Solis, R. Martone, M. Maslov, R. Masocco, M. Mattei, G.F. Matthews, D. Matveev, E. Matveeva, M.L. Mayoral, D. Mazon, S. Mazzi, C. Mazzotta, G. McArdle, R. McDermott, K. McKay, A.G. Meigs, C. Meineri, A. Mele, V. Menkovski, S. Menmuir, A. Merle, H. Meyer, K. Mikszuta Michalik, D. Milanesio, F. Militello, A. Milocco, I.G. Miron, J. Mitchell, R. Mitteau, V. Mitterauer, J. Mlynar, V. Moiseenko, P. Molna, F. Mombelli, C. Monti, A. Montisci, J. Morales, P. Moreau, J.M. Moret, A. Moro, D. Moulton, P. Mulholland, M. Muraglia, A. Murari, A. Muraro, P. Muscente, D. Mykytchuk, F. Nabais, Y. Nakeva, F. Napoli, E. Nardon, M.F. Nave, R.D. Nem, A. Nielsen, S.K. Nielsen, M. Nocente, R. Nouailletas, S. Nowak, H. Nyström, R. Ochoukov, N. Offeddu, S. Olasz, C. Olde, F. Oliva, D. Oliveira, H.J.C. Oliver, P. Ollus, J. Ongena, F.P. Orsitto, N. Osborne, R. Otin, P. Oyola Dominguez, D.I. Palade, S. Palomba, O. Pan, N. Panadero, E. Panontin, A. Papadopoulos, P. Papagiannis, G. Papp, V.V. Parail, C. Pardanaud, J. Parisi, A. Parrott, K. Paschalidis, M. Passoni, F. Pastore, A. Patel, B. Patel, A. Pau, G. Pautasso, R. Pavlichenko, E. Pawelec, B. Pegourie, G. Pelka, E. Peluso, A. Perek, E. Perelli Cippo, C. Perez Von Thun, P. Petersson, G. Petravich, Y. Peysson, V. Piergotti, L. Pigatto, C. Piron, L. Piron, A. Pironti, F. Pisano, U. Plank, B. Ploeckl, V. Plyusnin, A. Podolnik, Y. Poels, G. Pokol, J. Poley, G. Por, M. Poradzinski, F. Porcelli, L. Porte, C. Possieri, A. Poulsen, I. Predebon, G. Pucella, M. Pueschel, P. Puglia, O. Putignano, T. Pütterich, V. Quadri, A. Quercia, M. Rabinski, L. Radovanovic, R. Ragona, H. Raj, M. Rasinski, J. Rasmussen, G. Ratta, S. Ratynskaia, R. Rayaprolu, M. Rebai, A. Redl, D. Rees, D. Refy, M. Reich, H. Reimerdes, B.C.G. Reman, O. Renders, C. Reux, D. Ricci, M. Richou, S. Rienacker, D. Rigamonti, F. Rigollet, F.G. Rimini, D. Ripamonti, N. Rispoli, N. Rivals, J.F. Rivero Rodriguez, C. Roach, G. Rocchi, S. Rode, P. Rodrigues, J. Romazanov, C.F. Romero Madrid, J. Rosato, R. Rossi, G. Rubino, J. Rueda Rueda, J. Ruiz Ruiz, P. Ryan, D. Ryan, S. Saarelma, R. Sabot, M. Salewski, A. Salmi, L. Sanchis, A. Sand, J. Santos, K. Särkimäki, M. Sassano, O. Sauter, G. Schettini, S. Schmuck, P. Schneider, N. Schoonheere, R. Schramm, R. Schrittwieser, C. Schuster, N. Schwarz, F. Sciortino, M. Scotto D’Abusco, S. Scully, A. Selce, L. Senni, M. Senstius, G. Sergienko, S.E. Sharapov, R. Sharma, A. Shaw, U. Sheikh, G. Sias, B. Sieglin, S.A. Silburn, C. Silva, A. Silva, D. Silvagni, B. Simmendefeldt Schmidt, L. Simons, J. Simpson, L. Singh, S. Sipilä, Y. Siusko, S. Smith, A. Snicker, E.R. Solano, V. Solokha, M. Sos, C. Sozzi, F. Spineanu, G. Spizzo, M. Spolaore, L. Spolladore, C. Srinivasan, A. Stagni, Z. Stancar, G. Stankunas, J. Stober, P. Strand, C.I. Stuart, F. Subba, G.Y. Sun, H.J. Sun, W. Suttrop, J. Svoboda, T. Szepesi, G. Szepesi, B. Tal, T. Tala, P. Tamain, G. Tardini, M. Tardocchi, D. Taylor, G. Telesca, A. Tenaglia, A. Terra, D. Terranova, D. Testa, C. Theiler, E. Tholerus, B. Thomas, E. Thoren, A. Thornton, A. Thrysoe, Q. TICHIT, W. Tierens, A. Titarenko, P. Tolias, E. Tomasina, M. Tomes, E. Tonello, A. Tookey, M. Toscano Jiménez, C. Tsironis, C. Tsui, A. Tykhyy, M. Ugoletti, M. Usoltseva, D.F. Valcarcel, A. Valentini, M. Valisa, M. Vallar, M. Valovic, SI. Valvis, M. van Berkel, D. Van Eester, S. Van Mulders, M. van Rossem, R. Vann, B. Vanovac, J. Varela Rodriguez, J. Varje, S. Vartanian, M. Vecsei, L. Velarde Gallardo, M. Veranda, T. Verdier, G. Verdoolaege, K. Verhaegh, L. Vermare, G. Verona Rinati, J. Vicente, E. Viezzer, L. Vignitchouk, F. Villone, B. Vincent, P. Vincenzi, M.O. Vlad, G. Vogel, I. Voitsekhovitch, I. Voldiner, P. Vondracek, N.M.T. VU, T. Vuoriheimo, C. Wade, E. Wang, T. Wauters, M. Weiland, H. Weisen, N. Wendler, D. Weston, A. Widdowson, S. Wiesen, M. Wiesenberger, T. Wijkamp, M. Willensdorfer, T. Wilson, A. Wojenski, C. Wuethrich, I. Wyss, L. Xiang, S. Xu, D. Yadykin, Y. Yakovenko, H. Yang, V. Yanovskiy, R. Yi, B. Zaar, G. Zadvitskiy, L. Zakharov, P. Zanca, D. Zarzoso, Y. Zayachuk, J. Zebrowski, M. Zerbini, P. Zestanakis, C. F. B. Zimmermann, M. Zlobinski, A. Zohar, V.K. Zotta, X. Zou, M. Zuin, M. Zurita, and I. Zychor
Subjects: JET, ASDEX Upgrade, MAST-U, TCV, WEST, Tokamak Exploitation Task Force, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: Within the 9th European Framework programme, since 2021 EUROfusion is operating five tokamaks under the auspices of a single Task Force called ‘Tokamak Exploitation’. The goal is to benefit from the complementary capabilities of each machine in a coordinated way and help in developing a scientific output scalable to future largre machines. The programme of this Task Force ensures that ASDEX Upgrade, MAST-U, TCV, WEST and JET (since 2022) work together to achieve the objectives of Missions 1 and 2 of the EUROfusion Roadmap: i) demonstrate plasma scenarios that increase the success margin of ITER and satisfy the requirements of DEMO and, ii) demonstrate an integrated approach that can handle the large power leaving ITER and DEMO plasmas. The Tokamak Exploitation task force has therefore organized experiments on these two missions with the goal to strengthen the physics and operational basis for the ITER baseline scenario and for exploiting the recent plasma exhaust enhancements in all four devices (PEX: Plasma EXhaust) for exploring the solution for handling heat and particle exhaust in ITER and develop the conceptual solutions for DEMO. The ITER Baseline scenario has been developed in a similar way in ASDEX Upgrade, TCV and JET. Key risks for ITER such as disruptions and run-aways have been also investigated in TCV, ASDEX Upgrade and JET. Experiments have explored successfully different divertor configurations (standard, super-X, snowflakes) in MAST-U and TCV and studied tungsten melting in WEST and ASDEX Upgrade. The input from the smaller devices to JET has also been proven successful to set-up novel control schemes on disruption avoidance and detachment.
Published: 2024
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2. Overview of T and D–T results in JET with ITER-like wall

Author: C.F. Maggi, D. Abate, N. Abid, P. Abreu, O. Adabonyan, M. Afzal, I. Ahmad, M. Akhtar, R. Albanese, S. Aleiferis, E. Alessi, P. Aleynikov, J. Alguacil, J. Alhage, M. Ali, H. Allen, M. Allinson, M. Alonzo, E. Alves, R. Ambrosino, E. Andersson Sundén, P. Andrew, M. Angelone, C. Angioni, I. Antoniou, L. Appel, C. Appelbee, C. Aramunde, M. Ariola, G. Arnoux, G. Artaserse, J.-F. Artaud, W. Arter, V. Artigues, F.J. Artola, A. Ash, O. Asztalos, D. Auld, F. Auriemma, Y. Austin, L. Avotina, J. Ayllón, E. Aymerich, A. Baciero, L. Bähner, F. Bairaktaris, I. Balboa, M. Balden, N. Balshaw, V.K. Bandaru, J. Banks, A. Banon Navarro, C. Barcellona, O. Bardsley, M. Barnes, R. Barnsley, M. Baruzzo, M. Bassan, A. Batista, P. Batistoni, L. Baumane, B. Bauvir, L. Baylor, C. Bearcroft, P. Beaumont, D. Beckett, A. Begolli, M. Beidler, N. Bekris, M. Beldishevski, E. Belli, F. Belli, S. Benkadda, J. Bentley, E. Bernard, J. Bernardo, M. Bernert, M. Berry, L. Bertalot, H. Betar, M. Beurskens, P.G. Bhat, S. Bickerton, J. Bielecki, T. Biewer, R. Bilato, P. Bílková, G. Birkenmeier, R. Bisson, J.P.S. Bizarro, P. Blatchford, A. Bleasdale, V. Bobkov, A. Boboc, A. Bock, G. Bodnar, P. Bohm, L. Bonalumi, N. Bonanomi, D. Bonfiglio, X. Bonnin, P. Bonofiglo, J. Booth, D. Borba, D. Borodin, I. Borodkina, T.O.S.J. Bosman, C. Bourdelle, M. Bowden, I. Božičević Mihalić, S.C. Bradnam, B. Breizman, S. Brezinsek, D. Brida, M. Brix, P. Brown, D. Brunetti, M. Buckley, J. Buermans, H. Bufferand, P. Buratti, A. Burckhart, A. Burgess, A. Buscarino, A. Busse, D. Butcher, G. Calabrò, L. Calacci, R. Calado, R. Canavan, B. Cannas, M. Cannon, M. Cappelli, S. Carcangiu, P. Card, A. Cardinali, S. Carli, P. Carman, D. Carnevale, B. Carvalho, I.S. Carvalho, P. Carvalho, I. Casiraghi, F.J. Casson, C. Castaldo, J.P. Catalan, N. Catarino, F. Causa, M. Cavedon, M. Cecconello, L. Ceelen, C.D. Challis, B. Chamberlain, R. Chandra, C.S. Chang, A. Chankin, B. Chapman, P. Chauhan, M. Chernyshova, A. Chiariello, G.-C. Chira, P. Chmielewski, A. Chomiczewska, L. Chone, J. Cieslik, G. Ciraolo, D. Ciric, J. Citrin, Ł. Ciupinski, R. Clarkson, M. Cleverly, P. Coates, V. Coccorese, R. Coelho, J.W. Coenen, I.H. Coffey, A. Colangeli, L. Colas, J. Collins, S. Conroy, C. Contré, N.J. Conway, D. Coombs, P. Cooper, S. Cooper, L. Cordaro, C. Corradino, Y. Corre, G. Corrigan, D. Coster, T. Craciunescu, S. Cramp, D. Craven, R. Craven, G. Croci, D. Croft, K. Crombé, T. Cronin, N. Cruz, A. Cufar, A. Cullen, A. Dal Molin, S. Dalley, P. David, A. Davies, J. Davies, S. Davies, G. Davis, K. Dawson, S. Dawson, I. Day, G. De Tommasi, J. Deane, M. Dearing, M. De Bock, J. Decker, R. Dejarnac, E. Delabie, E. de la Cal, E. de la Luna, D. Del Sarto, A. Dempsey, W. Deng, A. Dennett, G.L. Derks, G. De Temmerman, F. Devasagayam, P. de Vries, P. Devynck, A. di Siena, D. Dickinson, T. Dickson, M. Diez, P. Dinca, T. Dittmar, L. Dittrich, J. Dobrashian, T. Dochnal, A.J.H. Donné, W. Dorland, S. Dorling, S. Dormido-Canto, R. Dotse, D. Douai, S. Dowson, R. Doyle, M. Dreval, P. Drews, G. Drummond, Ph. Duckworth, H.G. Dudding, R. Dumont, P. Dumortier, D. Dunai, T. Dunatov, M. Dunne, I. Ďuran, F. Durodié, R. Dux, T. Eade, E. Eardley, J. Edwards, T. Eich, A. Eksaeva, H. El-Haroun, R.D. Ellis, G. Ellwood, C. Elsmore, S. Emery, G. Ericsson, B. Eriksson, F. Eriksson, J. Eriksson, L.G. Eriksson, S. Ertmer, G. Evans, S. Evans, E. Fable, D. Fagan, M. Faitsch, D. Fajardo Jimenez, M. Falessi, A. Fanni, T. Farmer, I. Farquhar, B. Faugeras, S. Fazinić, N. Fedorczak, K. Felker, R. Felton, H. Fernandes, D.R. Ferreira, J. Ferreira, G. Ferrò, J. Fessey, O. Février, O. Ficker, A.R. Field, A. Figueiredo, J. Figueiredo, A. Fil, N. Fil, P. Finburg, U. Fischer, G. Fishpool, L. Fittill, M. Fitzgerald, D. Flammini, J. Flanagan, S. Foley, N. Fonnesu, M. Fontana, J.M. Fontdecaba, L. Fortuna, E. Fortuna-Zalesna, M. Fortune, C. Fowler, P. Fox, O. Franklin, E. Fransson, L. Frassinetti, R. Fresa, D. Frigione, T. Fülöp, M. Furseman, S. Gabriellini, D. Gadariya, S. Gadgil, K. Gál, S. Galeani, A. Galkowski, D. Gallart, M. Gambrioli, T. Gans, J. Garcia, M. García-Muñoz, L. Garzotti, J. Gaspar, R. Gatto, P. Gaudio, D. Gear, T. Gebhart, S. Gee, M. Gelfusa, R. George, S.N. Gerasimov, R. Gerru, G. Gervasini, M. Gethins, Z. Ghani, M. Gherendi, P.-I. Gherghina, F. Ghezzi, L. Giacomelli, C. Gibson, L. Gil, M.R. Gilbert, A. Gillgren, E. Giovannozzi, C. Giroud, G. Giruzzi, J. Goff, V. Goloborodko, R. Gomes, J.-F. Gomez, B. Gonçalves, M. Goniche, J. Gonzalez-Martin, A. Goodyear, S. Gore, G. Gorini, T. Görler, N. Gotts, E. Gow, J.P. Graves, J. Green, H. Greuner, E. Grigore, F. Griph, W. Gromelski, M. Groth, C. Grove, R. Grove, N. Gupta, S. Hacquin, L. Hägg, A. Hakola, M. Halitovs, J. Hall, C.J. Ham, M. Hamed, M.R. Hardman, Y. Haresawa, G. Harrer, J.R. Harrison, D. Harting, D.R. Hatch, T. Haupt, J. Hawes, N.C. Hawkes, J. Hawkins, S. Hazael, J. Hearmon, P. Heesterman, P. Heinrich, M. Held, W. Helou, O. Hemming, S.S. Henderson, R. Henriques, R.B. Henriques, D. Hepple, J. Herfindal, G. Hermon, J.C. Hillesheim, K. Hizanidis, A. Hjalmarsson, A. Ho, J. Hobirk, O. Hoenen, C. Hogben, A. Hollingsworth, S. Hollis, E. Hollmann, M. Hölzl, M. Hook, M. Hoppe, J. Horáček, N. Horsten, A. Horton, L.D. Horton, L. Horvath, S. Hotchin, Z. Hu, Z. Huang, E. Hubenov, A. Huber, V. Huber, T. Huddleston, G.T.A. Huijsmans, Y. Husain, P. Huynh, A. Hynes, D. Iglesias, M.V. Iliasova, M. Imríšek, J. Ingleby, P. Innocente, V. Ioannou-Sougleridis, N. Isernia, I. Ivanova-Stanik, E. Ivings, S. Jachmich, T. Jackson, A.S. Jacobsen, P. Jacquet, H. Järleblad, A. Järvinen, F. Jaulmes, N. Jayasekera, F. Jenko, I. Jepu, E. Joffrin, T. Johnson, J. Johnston, C. Jones, E. Jones, G. Jones, L. Jones, T.T.C. Jones, A. Joyce, M. Juvonen, A. Kallenbach, P. Kalnina, D. Kalupin, P. Kanth, A. Kantor, A. Kappatou, O. Kardaun, J. Karhunen, E. Karsakos, Ye.O. Kazakov, V. Kazantzidis, D.L. Keeling, W. Kelly, M. Kempenaars, D. Kennedy, K. Khan, E. Khilkevich, C. Kiefer, H.-T. Kim, J. Kim, S.H. Kim, D.B. King, D.J. Kinna, V.G. Kiptily, A. Kirjasuo, K.K. Kirov, A. Kirschner, T. Kiviniemi, G. Kizane, C. Klepper, A. Klix, G. Kneale, M. Knight, P. Knight, R. Knights, S. Knipe, U. Knoche, M. Knolker, M. Kocan, F. Köchl, G. Kocsis, J.T.W. Koenders, Y. Kolesnichenko, Y. Kominis, M. Kong, B. Kool, V. Korovin, S.B. Korsholm, B. Kos, D. Kos, M. Koubiti, Y. Kovtun, E. Kowalska-Strzęciwilk, K. Koziol, Y. Krasikov, A. Krasilnikov, V. Krasilnikov, M. Kresina, A. Kreter, K. Krieger, A. Krivska, U. Kruezi, I. Książek, H. Kumpulainen, B. Kurzan, S. Kwak, O.J. Kwon, B. Labit, M. Lacquaniti, A. Lagoyannis, L. Laguardia, A. Laing, V. Laksharam, N. Lam, H.T. Lambertz, B. Lane, M. Langley, E. Lascas Neto, E. Łaszyńska, K.D. Lawson, A. Lazaros, E. Lazzaro, G. Learoyd, C. Lee, K. Lee, S. Leerink, T. Leeson, X. Lefebvre, H.J. Leggate, J. Lehmann, M. Lehnen, D. Leichtle, F. Leipold, I. Lengar, M. Lennholm, E. Leon Gutierrez, L.A. Leppin, E. Lerche, A. Lescinskis, S. Lesnoj, L. Lewin, J. Lewis, J. Likonen, Ch. Linsmeier, X. Litaudon, E. Litherland-Smith, F. Liu, T. Loarer, A. Loarte, R. Lobel, B. Lomanowski, P.J. Lomas, J. Lombardo, R. Lorenzini, S. Loreti, V.P. Loschiavo, M. Loughlin, T. Lowe, C. Lowry, T. Luce, R. Lucock, T. Luda Di Cortemiglia, M. Lungaroni, C.P. Lungu, T. Lunt, V. Lutsenko, B. Lyons, J. Macdonald, E. Macusova, R. Mäenpää, H. Maier, J. Mailloux, S. Makarov, P. Manas, A. Manning, P. Mantica, M.J. Mantsinen, J. Manyer, A. Manzanares, Ph. Maquet, M. Maraschek, G. Marceca, G. Marcer, C. Marchetto, O. Marchuk, A. Mariani, G. Mariano, M. Marin, A. Marin Roldan, M. Marinelli, T. Markovič, L. Marot, C. Marren, S. Marsden, S. Marsen, J. Marsh, R. Marshall, L. Martellucci, A.J. Martin, C. Martin, R. Martone, S. Maruyama, M. Maslov, M. Mattei, G.F. Matthews, D. Matveev, E. Matveeva, A. Mauriya, F. Maviglia, M. Mayer, M.-L. Mayoral, S. Mazzi, C. Mazzotta, R. McAdams, P.J. McCarthy, P. McCullen, R. McDermott, D.C. McDonald, D. McGuckin, V. McKay, L. McNamee, A. McShee, D. Mederick, M. Medland, S. Medley, K. Meghani, A.G. Meigs, S. Meitner, S. Menmuir, K. Mergia, S. Mianowski, P. Middleton, J. Mietelski, K. Mikszuta-Michalik, D. Milanesio, E. Milani, E. Militello-Asp, F. Militello, J. Milnes, A. Milocco, S. Minucci, I. Miron, J. Mitchell, J. Mlynář, V. Moiseenko, P. Monaghan, I. Monakhov, A. Montisci, S. Moon, R. Mooney, S. Moradi, R.B. Morales, L. Morgan, F. Moro, J. Morris, T. Mrowetz, L. Msero, S. Munot, A. Muñoz-Perez, M. Muraglia, A. Murari, A. Muraro, B. N’Konga, Y.S. Na, F. Nabais, R. Naish, F. Napoli, E. Nardon, V. Naulin, M.F.F. Nave, R. Neu, S. Ng, M. Nicassio, D. Nicolai, A.H. Nielsen, S.K. Nielsen, D. Nina, C. Noble, C.R. Nobs, M. Nocente, H. Nordman, S. Nowak, H. Nyström, J. O’Callaghan, M. O’Mullane, C. O’Neill, C. Olde, H.J.C. Oliver, R. Olney, J. Ongena, G.P. Orsitto, A. Osipov, R. Otin, N. Pace, L.W. Packer, E. Pajuste, D. Palade, J. Palgrave, O. Pan, N. Panadero, T. Pandya, E. Panontin, A. Papadopoulos, G. Papadopoulos, G. Papp, V.V. Parail, A. Parsloe, K. Paschalidis, M. Passeri, A. Patel, A. Pau, G. Pautasso, R. Pavlichenko, A. Pavone, E. Pawelec, C. Paz-Soldan, A. Peacock, M. Pearce, I.J. Pearson, E. Peluso, C. Penot, K. Pepperell, A. Perdas, T. Pereira, E. Perelli Cippo, C. Perez von Thun, D. Perry, P. Petersson, G. Petravich, N. Petrella, M. Peyman, L. Pigatto, M. Pillon, S. Pinches, G. Pintsuk, C. Piron, A. Pironti, F. Pisano, R. Pitts, U. Planck, N. Platt, V. Plyusnin, M. Podesta, G. Pokol, F.M. Poli, O.G. Pompilian, M. Poradzinski, M. Porkolab, C. Porosnicu, G. Poulipoulis, A.S. Poulsen, I. Predebon, A. Previti, D. Primetzhofer, G. Provatas, G. Pucella, P. Puglia, K. Purahoo, O. Putignano, T. Pütterich, A. Quercia, G. Radulescu, V. Radulovic, R. Ragona, M. Rainford, P. Raj, M. Rasinski, D. Rasmussen, J. Rasmussen, J.J. Rasmussen, A. Raso, G. Rattá, S. Ratynskaia, R. Rayaprolu, M. Rebai, A. Redl, D. Rees, D. Réfy, R. Reichle, H. Reimerdes, B.C.G. Reman, C. Reux, S. Reynolds, D. Rigamonti, E. Righi, F.G. Rimini, J. Risner, J.F. Rivero-Rodriguez, C.M. Roach, J. Roberts, R. Robins, S. Robinson, D. Robson, S. Rode, P. Rodrigues, P. Rodriguez-Fernandez, S. Romanelli, J. Romazanov, E. Rose, C. Rose-Innes, R. Rossi, S. Rowe, D. Rowlands, C. Rowley, M. Rubel, G. Rubinacci, G. Rubino, M. Rud, J. Ruiz Ruiz, F. Ryter, S. Saarelma, A. Sahlberg, M. Salewski, A. Salmi, R. Salmon, F. Salzedas, F. Sanchez, I. Sanders, D. Sandiford, F. Sanni, O. Sauter, P. Sauvan, G. Schettini, A. Shevelev, A.A. Schekochihin, K. Schmid, B.S. Schmidt, S. Schmuck, M. Schneider, P.A. Schneider, N. Schoonheere, R. Schramm, D. Scoon, S. Scully, M. Segato, J. Seidl, L. Senni, J. Seo, G. Sergienko, M. Sertoli, S.E. Sharapov, R. Sharma, A. Shaw, R. Shaw, H. Sheikh, U. Sheikh, N. Shi, P. Shigin, D. Shiraki, G. Sias, M. Siccinio, B. Sieglin, S.A. Silburn, A. Silva, C. Silva, J. Silva, D. Silvagni, D. Simfukwe, J. Simpson, P. Sirén, A. Sirinelli, H. Sjöstrand, N. Skinner, J. Slater, T. Smart, R.D. Smirnov, N. Smith, P. Smith, T. Smith, J. Snell, L. Snoj, E.R. Solano, V. Solokha, C. Sommariva, K. Soni, M. Sos, J. Sousa, C. Sozzi, T. Spelzini, F. Spineanu, L. Spolladore, D. Spong, C. Srinivasan, G. Staebler, A. Stagni, I. Stamatelatos, M.F. Stamp, Ž. Štancar, P.A. Staniec, G. Stankūnas, M. Stead, B. Stein-Lubrano, A. Stephen, J. Stephens, P. Stevenson, C. Steventon, M. Stojanov, D.A. St-Onge, P. Strand, S. Strikwerda, C.I. Stuart, S. Sturgeon, H.J. Sun, S. Surendran, W. Suttrop, J. Svensson, J. Svoboda, R. Sweeney, G. Szepesi, M. Szoke, T. Tadić, B. Tal, T. Tala, P. Tamain, K. Tanaka, W. Tang, G. Tardini, M. Tardocchi, D. Taylor, A.S. Teimane, G. Telesca, A. Teplukhina, A. Terra, D. Terranova, N. Terranova, D. Testa, B. Thomas, V.K. Thompson, A. Thorman, A.S. Thrysoe, W. Tierens, R.A. Tinguely, A. Tipton, H. Todd, M. Tomeš, A. Tookey, P. Tsavalas, D. Tskhakaya, L.-P. Turică, A. Turner, I. Turner, M. Turner, M.M. Turner, G. Tvalashvili, A. Tykhyy, S. Tyrrell, A. Uccello, V. Udintsev, A. Vadgama, D.F. Valcarcel, A. Valentini, M. Valisa, M. Vallar, M. Valovic, M. Van Berkel, K.L. van de Plassche, M. van Rossem, D. Van Eester, J. Varela, J. Varje, T. Vasilopoulou, G. Vayakis, M. Vecsei, J. Vega, M. Veis, P. Veis, S. Ventre, M. Veranda, G. Verdoolaege, C. Verona, G. Verona Rinati, E. Veshchev, N. Vianello, E. Viezzer, L. Vignitchouk, R. Vila, R. Villari, F. Villone, P. Vincenzi, A. Vitins, Z. Vizvary, M. Vlad, I. Voldiner, U. Von Toussaint, P. Vondráček, B. Wakeling, M. Walker, R. Walker, M. Walsh, R. Walton, E. Wang, F. Warren, R. Warren, J. Waterhouse, C. Watts, T. Webster, M. Weiland, H. Weisen, M. Weiszflog, N. Wendler, A. West, M. Wheatley, S. Whetham, A. Whitehead, D. Whittaker, A. Widdowson, S. Wiesen, M. Willensdorfer, J. Williams, I. Wilson, T. Wilson, M. Wischmeier, A. Withycombe, D. Witts, A. Wojcik-Gargula, E. Wolfrum, R. Wood, R. Woodley, R. Worrall, I. Wyss, T. Xu, D. Yadykin, Y. Yakovenko, Y. Yang, V. Yanovskiy, R. Yi, I. Young, R. Young, B. Zaar, R.J. Zabolockis, L. Zakharov, P. Zanca, A. Zarins, D. Zarzoso Fernandez, K.-D. Zastrow, Y. Zayachuk, M. Zerbini, W. Zhang, B. Zimmermann, M. Zlobinski, A. Zocco, V.K. Zotta, M. Zuin, W. Zwingmann, and I. Zychor
Subjects: magnetic fusion, JET-ILW, D–T, tritium, alpha particles, fusion prediction, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: In 2021 JET exploited its unique capabilities to operate with T and D–T fuel with an ITER-like Be/W wall (JET-ILW). This second major JET D–T campaign (DTE2), after DTE1 in 1997, represented the culmination of a series of JET enhancements—new fusion diagnostics, new T injection capabilities, refurbishment of the T plant, increased auxiliary heating, in-vessel calibration of 14 MeV neutron yield monitors—as well as significant advances in plasma theory and modelling in the fusion community. DTE2 was complemented by a sequence of isotope physics campaigns encompassing operation in pure tritium at high T-NBI power. Carefully conducted for safe operation with tritium, the new T and D–T experiments used 1 kg of T (vs 100 g in DTE1), yielding the most fusion reactor relevant D–T plasmas to date and expanding our understanding of isotopes and D–T mixture physics. Furthermore, since the JET T and DTE2 campaigns occurred almost 25 years after the last major D–T tokamak experiment, it was also a strategic goal of the European fusion programme to refresh operational experience of a nuclear tokamak to prepare staff for ITER operation. The key physics results of the JET T and DTE2 experiments, carried out within the EUROfusion JET1 work package, are reported in this paper. Progress in the technological exploitation of JET D–T operations, development and validation of nuclear codes, neutronic tools and techniques for ITER operations carried out by EUROfusion (started within the Horizon 2020 Framework Programme and continuing under the Horizon Europe FP) are reported in (Litaudon et al Nucl. Fusion accepted), while JET experience on T and D–T operations is presented in (King et al Nucl. Fusion submitted).
Published: 2024
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3. Fuelling of deuterium–tritium plasma by peripheral pellets in JET experiments

Author: M. Valovič, S. Aleiferis, P. Blatchford, A. Boboc, M. Brix, P. Carvalho, I. Carvalho, M. Fontdecaba Climent, D. Dunai, L. Frassinetti, L. Garzotti, F. Köchl, J.C. Lowry, E. de la Luna, C.F. Maggi, R.B. Morales, S. Nowak, C. Olde, D. Réfy, F. Rimini, S. Silburn, Ž. Štancar, G. Tvalashvili, M. Vecsei, and the JET Contributors
Subjects: tokamak, pellets, JET deuterium–tritium plasma, particle losses, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: A baseline scenario of deuterium–tritium (D–T) plasma with peripheral high-field-side fuelling pellets has been produced in JET in order to mimic the situation in ITER. The isotope mix ratio is controlled in order to target the value of 50%–50% by a combination of tritium gas puffing and deuterium pellet injection. Multiple factors controlling the fuelling efficiency of individual pellets are analysed, with the following findings: (1) prompt particle losses due to pellet-triggered edge-localised modes (ELMs) are detected, (2) the plasmoid drift velocity might be smaller than that predicted by simulation, (3) post-pellet particle loss is controlled by transient phases with ELMs.The overall pellet particle flux normalised to the heat flux is similar to that in previous pellet fuelling experiments in AUG and JET.
Published: 2024
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4. Detection of alpha heating in JET-ILW DT plasmas by a study of the electron temperature response to ICRH modulation

Author: P. Mantica, F. Auriemma, I. Casiraghi, D. Gallart, K. Kirov, E. Lerche, A. Salmi, A. Dal Molin, E. Delabie, J. Eriksson, J. Garcia, P. Huynh, P. Jacquet, T. Jonsson, V. Kiptily, E. Litherland–Smith, C.F. Maggi, M. Mantsinen, G. Marcer, M. Maslov, S. Menmuir, M. Nocente, E. Peluso, G. Pucella, D. Rigamonti, Z. Stancar, H. Sun, G. Szepesi, M. Tardocchi, D. Van Eester, and JET Contributors
Subjects: tokamak, DT plasmas, alpha heating, ICRH modulation, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: In the JET DTE2 campaign a new method was successfully tested to detect the heating of bulk electrons by α-particles, using the dynamic response of the electron temperature T _e to the modulation of ion cyclotron resonance heating (ICRH). A fundamental deuterium (D) ICRH scheme was applied to a tritium-rich hybrid plasma with D-neutral beam injection (NBI). The modulation of the ion temperature T _i and of the ICRH accelerated deuterons leads to modulated α -heating with a large delay with respect to other modulated electron heating terms. A significant phase delay of ∼40° is measured between central T _e and T _i , which can only be explained by α -particle heating. Integrated modelling using different models for ICRH absorption and ICRH/NBI interaction reproduces the effect qualitatively. Best agreement with experiment is obtained with the European Transport Solver/Heating and Current Drive workflow.
Published: 2024
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5. Observation of alpha-particles in recent D–T experiments on JET

Author: V.G. Kiptily, C.D. Challis, R. Dumont, M. Fitzgerald, J. Garcia, L. Garzotti, Z. Ghani, J. Hobirk, P. Jacquet, A. Kappatou, D. Keeling, Ye. Kazakov, P. Mantica, M.J. Mantsinen, S.E. Sharapov, E.R. Solano, D. Van Eester, P.J. Bonofiglo, T. Craciunescu, A. Dal Molin, J. Eriksson, V. Goloborodko, M.V. Iliasova, E.M. Khilkevitch, D. King, I. Lengar, M. Nocente, S. Menmuir, M. Podestà, M. Poradzinski, D. Rigamonti, J. Rivero-Rodriguez, Z. Stancar, A.E. Shevelev, P. Siren, H. Sun, D.M. Taylor, M. Tardocchi, P. Beaumont, F. Belli, F.E. Cecil, R. Coelho, M. Curuia, M. Garcia-Munoz, E. Joffrin, C. Lowry, M. Lennholm, E. Lerche, C.F. Maggi, J. Mailloux, D. Marocco, M. Maslov, C. Perez Von Thun, F. Rimini, V. Zoita, and JET Contributors
Subjects: JET, DT-plasmas, fusion, alpha-particles, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The fusion reaction between deuterium and tritium, D ( T,n ) ^4 He is the main source of energy in future thermonuclear reactors. Alpha-particles ( ^4 He -ions) born with an average energy of 3.5 MeV transferring energy to the thermal plasma during their slowing down, should provide the self-sustained D–T plasma burn. The adequate confinement of α -particles is essential to provide efficient heating of the bulk plasma and steady burning of a reactor plasma. That is why the fusion-born α -particle studies have been a priority task in the second D–T experiments (DTE2) on the Joint European Torus (JET) to understand the main mechanisms of their slowing down, redistribution and losses and to develop optimal plasma scenarios. JET with Be -wall and W -divertor, enhanced auxiliary heating systems and improved energetic-particle diagnostic capabilities, producing significant population of α -particles, provided the possibility for comprehensive studying of the α -particle behaviour. Selected results of the confined and lost α -particle measurements, evidence of α -particle self-heating and assessments of the fusion performance are presented in this paper giving an opportunity for further modelling and extrapolation to the International Thermonuclear Experimental Reactor and burning plasma reactors.
Published: 2024
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6. JET machine operations in T&D-T

Author: The JET Operations Team (presented by D.B. King), E. Abdelrahman, A. Abdul Hamid, N. Abid, K. Abraham, O. Adabonyan, C. Adlam, M. Afzal, M. Akhtar, V. Aldred, S. Aldworth, S. Aleiferis, M. Ali, R. Alie, R. Allan, H. Allen, E. Alli, M. Allinson, P. Almond, J. Angus, K. Antcliffe, I. Antoniou, L. Appel, C. Appelbee, C. Aramunde, N. Archer, S. Aria, H. Arkuszynski, M. Arshad, G. Artaserse, A. Ash, C. Ashe, T. Aue, D. Auld, B. Austin, Y. Austin, C. Ayres, R.B. Morales, S. Baker, S. Bakes, I. Balboa, C. Balshaw, N. Balshaw, J. Banks, J. Banner, A. Barnard, M. Barnard, M. Baruzzo, C. Basagiannis, S. Bathe Hariyanandan, P. Batistoni, R. Baughan, P. Beaumont, D. Beckett, A. Begolli, M. Beldishevski, K. Bell, E. Belonohy, J. Bentley, J. Bernardo, M. Berry, J. Bhatt, S. Bickerton, J. Bielecki, W. Bird, D. Blackett, K. Blackman, S. Blake, P. Blatchford, A. Bleasdale, A. Boboc, J. Booth, P. Boulting, M. Bowden, C. Boyd, K. Boyd, R. Bracey, D. Brennan, A. Brett, M. Bright, M. Brix, I. Brooks, B. Brown, P. Brown, M. Brown, P. Brummitt, B. Viola, A. Buckingham, M. Buckley, J. Bumpass, M. Burford, A. Burgess, J. Burton-Sweeten, A. Busse, D. Butcher, P. Cahill, P. Camp, I. Campbell, R. Canavan, J. Cane, M. Cannon, N. Canterbury, A. Carberry, P. Card, M. Carlick, M. Carlo, P. Carman, A. Carruthers, S. Carter, I.S. Carvalho, P. Carvalho, F. Casson, D. Chalk, B. Chamberlain, P. Chauhan, A. Chow, A. Churchman, D. Ciric, M. Clark, J. Clarkson, R. Clarkson, T. Clayton, M. Cleverly, P. Coates, I. Coffey, J. Collins, S. Conroy, N.J. Conway, R. Conway, J. Cook, M. Cooke, D. Coombs, P. Cooper, S. Cooper, G. Corrigan, R. Cotterell, A. Coulson, M. Cox, S. Cox, S. Cramp, D. Craven, R. Craven, M. Crick, D. Croft, T. Cronin, Z. Cui, A. Cullen, R. Cumming, C. Cummings, A. Dal Molin, P. Dalgliesh, S. Dalley, A. Danquah, S. Davies, G. Davis, H. Dawson, K. Dawson, S. Dawson, I. Day, L. de Caires, E. de la Luna, K. Deakin, J. Deane, M. Dearing, A. Dennett, T. Dickson, J. Dobrashian, T. Dochnal, S. Dorling, D. Douai, S. Dowson, J. Drewitt, G. Drummond, P. Dumortier, R. Eade, R. Eastham, K. Eden, J. Edmond, J. Edwards, P. Edwards, H. Elamin, S. Elford, H. El-Haroun, P. Ellis, C. Elsmore, S. Emery, G. Evans, S. Evans, D. Fagan, T. Farmer, I. Farquhar, R. Felton, F. Ferner, J. Fessey, P. Finburg, G. Fishpool, L. Fittill, J. Flanagan, K. Flinders, S. Foley, M. Fontana, M. Fortune, J. Foster, C. Fowler, P. Fox, O. Franklin, R. Franklin, R. Fraser, S. French, M. Furseman, A. Gabbidon, L. Garcia, J. Garcia, M. Gardener, D. Gear, T. Gedling, S. Gee, P. Gell, R. George, S. Gerasimov, M. Gethins, Z. Ghani, L. Giacomelli, C. Gibson, V. Gilsenan, C. Giroud, R. Glen, J. Goff, C. Goodman, A. Goodyear, A. Gordon, S. Gore, S. Gosden, N. Gotts, E. Gow, W. Graham, G. Graham, M. Green, R. Gregory, R. Griffiths, T. Griffiths, F. Griph, C. Grundy, T. Grundy, D. Guard, D. Guest, C. Gurl, S. Hacquin, A. Hakola, K. Hammond, H. Harmer, P. Harper, S. Harris, D. Hart, D. Hattan, A. Haupt, J. Hawes, N. Hawkes, J. Hawkins, P. Hawkins, S. Hayes, S. Hazael, D. Heads, P. Heesterman, O. Hemming, R.B. Henriques, G. Hermon, G. Hewson, T. Hibberd, M. Hill, J. Hillesheim, I. Hirb, K. Ho, C. Hogben, A. Hollingsworth, S. Hollis, M. Hook, D. Hopley, N. Horsten, A. Horton, L.D. Horton, L. Horvath, S. Hotchin, Z. Huang, E. Hubenov, V. Huber, A. Huber, C. Huddart, T. Huddleston, T. Hunter, Y. Husain, A. Hynes, J. Ingleby, S. Ives, E. Ivings, S. Jackson, T. Jackson, P. Jacquet, N. Jayasekera, I. Jepu, D. Jezzard, E. Joffrin, R. Johnson, J. Johnston, C. Jones, E. Jones, G. Jones, L. Jones, S. Jones, T. Jones, M. Jones, A. Joyce, M. Juvonen, A. Kantor, A. Kappatou, G. Karajgikar, J. Karhunen, I. Karnowska-Paterski, E. Karsakos, G. Kaveney, G. Kay, D. Keeling, T. Keenan, R. Kelly, W. Kelly, D. Kennedy, R. Kennedy, O. Kent, K. Khan, D. King, D. Kinna, V. Kiptily, K. Kirov, G. Kneale, M. Knight, P. Knight, J. Knipe, R. Knipe, S. Knipe, P. Kochanski, D. Kos, M. Kovari, E. Kowalska-Strzęciwilk, N. Kraus, M. Kresina, B. Labit, A. Laing, V. Laksharam, N. Lam, B. Lane, C. Lane, T. Lavender, A. Lawson, K. Lawson, G. Learoyd, T. Leeson, X. Lefebvre, J. Lehmann, M. Lennholm, K. Lennon, E. Lerche, S. Lesnoj, E. Letellier, L. Lewin, J. Lewis, J. Li, G. Liddiard, E. Litherland-Smith, F. Liu, R. Lobel, J. Logan, P. Lomas, C. Long, U. Losada, C. Loveridge, T. Lowe, C. Lowry, R. Lucock, G. Lyons, J. Macdonald, P. Macheta, T. Madden, J. Maddock, C.F. Maggi, J. Mailloux, A. Manning, C. Manning, N. Mantel, A. Manzanares, S. Marsden, J. Marsh, R. Marshall, A. Martin, M. Maslov, G. Matthews, N. Mayfield, M. Mayoral, R. McAdams, L. McCafferty, P. McCullen, D. McDonald, A. McDonnell, D. McGuckin, T. McIver, V. McKay, R. McKean, L. McNamee, A. McShee, R. Meadows, D. Mederick, M. Medland, K. Meghani, A. Meigs, S. Menmuir, I. Merrigan, S. Mianowski, P. Middleton, C. Miles, J. Milnes, A. Milocco, J. Mitchell, P. Mitchell, P. Monaghan, I. Monakhov, P. Moody, R. Mooney, C. Moore, N. Mooring, L. Morgan, R. Morgan, J. Morris, O. Morton, S. Morton, P. Mulvana, S. Munot, R. Munro-Smith, K. Musgrave, R. Naish, N. Neethiraj, J. Neilson, A. Newman, S. Ng, M. Nicassio, K. Nicholls, M. Nightingale, C. Noble, R. Normington, C. Nygaard, J. O’Callaghan, R. Olney, B. O’Meara, M. O’Mullane, C. O’Neill, C. Opara, K. O’Rourke, J. Ottley, K. Otu, A. Owen, N. Pace, K. Palamartchouk, D. Paley, J. Palgrave, G. Papadopoulos, V. Parail, A. Parrott, A. Parsloe, L. Parsons, R. Parsons, A. Patel, J. Patel, A. Peacock, M. Pearce, T. Pearce, I. Pearson, J. Penzo, A. Perdas, T. Pereira, C. Perez Von Thun, D. Perry, N. Petrella, M. Peyman, N. Platt, M. Poradzinski, M. Porter, M. Porton, C. Powell, J. Pozzi, M. Price, L. Price, P. Puglia, D. Pulley, K. Purahoo, M. Rainford, A. Raj, S. Randhawa, S. Rapa, K. Ravisankar, C. Rayner, A. Read, C. Reux, S. Reynolds, V. Riccardo, L. Richiusa, D. Rigamonti, F. Rimini, J. Roberts, R. Robins, S. Robinson, T. Robinson, D. Robson, S. Romanelli, F. Rose, C. Rose-Innes, D. Rouse, S. Rowe, N. Rowland, D. Rowlands, M. Rubel, K. Sabin, R. Salmon, H. Salter, A. Sanders, E. Sanders, I. Sanders, D. Sandiford, F. Sanni, R. Sarwar, R. Sayles, C. Scaysbrook, G. Scott, D. Scraggs, S. Scully, R. Sealey, E. Searle, M. Segato, M. Sertoli, C. Shanks, R. Sharma, A. Shaw, K. Sheahan, H. Sheikh, D. Shrestha, R. Siddiqui, S. Silburn, J. Silva, D. Simfukwe, J. Simpson, M. Sinclair, A. Sips, P. Sirén, S. Skeats, N. Skinner, B. Slade, J. Slater, T. Smart, G. Smith, J. Smith, N. Smith, P. Smith, T. Smith, F. P. Smith, J. Snell, K. Snelling, K. Soare, E. Solano, A. Spelzini, C. Srinivasan, Z. Stancar, P.A. Staniec, M. Stead, R. Steadman, L. Steel, D. Steele, A. Stephen, J. Stephens, L. Stevenson, P. Stevenson, C. Steventon, L. Sticklen, M. Stojanov, S. Strikwerda, C. Stuart, G. Stubbs, N. Studd, W. Studholme, H. Sun, S. Surendran, G. Szepesi, M. Szoke, H. Tan, A. Taylor, D. Taylor, K. Taylor, A. Thingore, B. Thomas, J. Thomas, A. Thorman, A. Tilley, A. Tipton, N. Tipton, H. Todd, P. Tonner, A. Tookey, M. Towndrow, M. Tsang, E. Tsitrone, I. Turner, M. Turner, G. Tvalashvili, S. Tyrrell, A. Vadgama, D. Valcarcel, Q. Van Der Westhuizen, J. Verdon, N. Vianello, A. Vittal, Z. Vizvary, B. Wakeling, M. Walker, R. Walker, T. Wall, M. Walsh, T. Walsh, J. Walters, J. Walton, R. Walton, S. Warder, F. Warren, R. Warren, J. Waterhouse, T. Webster, G. Wells, C. Wellstood, A. West, M. Wheatley, S. Whiffin, A. Whitehead, C. Whitehead, D. Whittaker, A. Widdowson, J. Wilcox, D. Wilkins, R. Wilkins, J. Williams, M. Williams, D. Willoughby, A. Wilson, I. Wilson, T. Wilson, M. Wischmeier, P. Wise, G. Withenshaw, A. Withycombe, D. Witts, J. Witts, R. Wood, L. Woodham, C. Woodley, J. Woodley, R. Woodley, B. Woods, S. Wray, T. Xu, I. Young, R. Young, K-D. Zastrow, Y. Zayachuk, and M. Zerbini
Subjects: JET, tritium, operations, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: JET, the world’s largest operating tokamak with unique Be/W wall and tritium handling capability, completed a Deuterium-Tritium (D-T) campaign in 2021 (Maggi et al 29th Fusion Energy Conf. ) following a decade of preparatory experiments, dedicated enhancements, technical rehearsals and training (Horton et al 2016 Fusion Eng. Des. 109–111 925). Operation with tritium raises significant technical, safety and scientific challenges not encountered in standard protium or deuterium operation. This contribution describes the tritium operational requirements, pulses and technical preparations, new operating procedures, lessons learned and details on the achieved operational availability and performance. The preparation and execution of the recent JET tritium experiments benefitted from the previous experience in 1991 (Preliminary Tritium Experiment), 1997 (DTE1 campaign) and 2003 (Trace Tritium Campaigns) and consisted of the following five phases: technical rehearsals and scenario preparation, tritium commissioning, 100% tritium campaign, D-T campaign (DTE2), tritium clean-up. Following the clean-up JET resumed normal operation and is currently undertaking a further D-T campaign (DTE3).
Published: 2024
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7. Characterisation of divertor detachment onset in JET-ILW hydrogen, deuterium, tritium and deuterium–tritium low-confinement mode plasmas

Author: M. Groth, V. Solokha, S. Aleiferis, S. Brezinsek, M. Brix, I.S. Carvalho, P. Carvalho, G. Corrigan, D. Harting, N. Horsten, I. Jepu, J. Karhunen, K. Kirov, B. Lomanowski, K.D. Lawson, C. Lowry, A.G. Meigs, S. Menmuir, E. Pawelec, T. Pereira, A. Shaw, S. Silburn, B. Thomas, S. Wiesen, P. Börner, D. Borodin, S. Jachmich, D. Reiter, G. Sergienko, Z. Stancar, B. Viola, P. Beaumont, J. Bernardo, I. Coffey, N.J. Conway, E. de la Luna, D. Douai, C. Giroud, J. Hillesheim, L. Horvath, A. Huber, P. Lomas, C.F. Maggi, M. Maslov, C. Perez von Thun, S. Scully, N. Vianello, and M. Wischmeier
Subjects: Detachment, Hydrogen isotopes, JET, Nuclear engineering. Atomic power, TK9001-9401
Abstract: Measurements of the ion currents to and plasma conditions at the low-field side (LFS) divertor target plate in low-confinement mode plasmas in the JET ITER-like wall materials configuration show that the core plasma density required to detach the LFS divertor plasma is independent of the hydrogenic species protium, deuterium and tritium, and a 40 %/60 % deuterium–tritium mixture. This observation applies to a divertor plasma configuration with the LFS strike line connected to the horizontal part of the LFS divertor chosen because of its superior diagnostic coverage. The finding is independent of the operational status of the JET cryogenic pump. The electron temperature (Te) at the LFS strike line was markedly reduced from 25 eV to 5 eV over a narrow range of increasing core plasma density, and observed to be between 2 eV and 3 eV at the onset of detachment. The electron density (ne) peaks across the LFS plasma when Te at the target plate is 1 eV, and spatially moves to the X-point for higher core densities. The density limit was found approximately 20 % higher in protium than in tritium and deuterium–tritium plasmas.
Published: 2023
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8. The JET hybrid scenario in Deuterium, Tritium and Deuterium-Tritium

Author: J. Hobirk, C.D. Challis, A. Kappatou, E. Lerche, D. Keeling, D. King, S. Aleiferis, E. Alessi, C. Angioni, F. Auriemma, M. Baruzzo, É. Belonohy, J. Bernardo, A. Boboc, I.S. Carvalho, P. Carvalho, F.J. Casson, A. Chomiczewska, J. Citrin, I.H. Coffey, N.J. Conway, D. Douai, E. Delabie, B. Eriksson, J. Eriksson, O. Ficker, A.R. Field, M. Fontana, J.M. Fontdecaba, L. Frassinetti, D. Frigione, D. Gallart, J. Garcia, M. Gelfusa, Z. Ghani, L. Giacomelli, E. Giovannozzi, C. Giroud, M. Goniche, W. Gromelski, S. Hacquin, C. Ham, N.C. Hawkes, R.B. Henriques, J.C. Hillesheim, A. Ho, L. Horvath, I. Ivanova-Stanik, P. Jacquet, F. Jaulmes, E. Joffrin, H.T. Kim, V. Kiptily, K. Kirov, D. Kos, E. Kowalska-Strzeciwilk, H. Kumpulainen, K. Lawson, M. Lennholm, X. Litaudon, E. Litherland-Smith, P.J. Lomas, E. de la Luna, C.F. Maggi, J. Mailloux, M.J. Mantsinen, M. Maslov, G. Matthews, K.G. McClements, A.G. Meigs, S. Menmuir, A. Milocco, I.G. Miron, S. Moradi, R.B. Morales, S. Nowak, F. Orsitto, A. Patel, L. Piron, C. Prince, G. Pucella, E. Peluso, C. Perez von Thun, E. Rachlew, C. Reux, F. Rimini, S. Saarelma, P. A Schneider, S. Scully, M. Sertoli, S. Sharapov, A. Shaw, S. Silburn, A. Sips, P. Siren, C. Sozzi, E.R. Solano, Z. Stancar, G. Stankunas, C. Stuart, H.J. Sun, G. Szepesi, D. Valcarcel, M. Valisa, G. Verdoolaege, B. Viola, N. Wendler, M. Zerbini, and JET Contributors
Subjects: magnetic fusion, hybrid scenario, Tritium, D-T, isotope effects, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The JET hybrid scenario has been developed from low plasma current carbon wall discharges to the record-breaking Deuterium-Tritium plasmas obtained in 2021 with the ITER-like Be/W wall. The development started in pure Deuterium with refinement of the plasma current, and toroidal magnetic field choices and succeeded in solving the heat load challenges arising from 37 MW of injected power in the ITER like wall environment, keeping the radiation in the edge and core controlled, avoiding MHD instabilities and reaching high neutron rates. The Deuterium hybrid plasmas have been re-run in Tritium and methods have been found to keep the radiation controlled but not at high fusion performance probably due to time constraints. For the first time this scenario has been run in Deuterium-Tritium (50:50). These plasmas were re-optimised to have a radiation-stable H-mode entry phase, good impurity control through edge T _i gradient screening and optimised performance with fusion power exceeding 10 MW for longer than three alpha particle slow down times, 8.3 MW averaged over 5 s and fusion energy of 45.8 MJ.
Published: 2023
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9. JET D-T scenario with optimized non-thermal fusion

Author: M. Maslov, E. Lerche, F. Auriemma, E. Belli, C. Bourdelle, C.D. Challis, A. Chomiczewska, A. Dal Molin, J. Eriksson, J. Garcia, J. Hobirk, I. Ivanova-Stanik, Ph. Jacquet, A. Kappatou, Y. Kazakov, D.L. Keeling, D.B. King, V. Kiptily, K. Kirov, D. Kos, R. Lorenzini, E. De La Luna, C.F. Maggi, J. Mailloux, P. Mantica, M. Marin, G. Matthews, I. Monakhov, M. Nocente, G. Pucella, D. Rigamonti, F. Rimini, S. Saarelma, M. Salewski, E.R. Solano, Ž. Štancar, G. Stankunas, H. Sun, M. Tardocchi, D. Van Eester, and JET Contributors
Subjects: tokamak, nuclear fusion, tritium, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: In JET deuterium-tritium (D-T) plasmas, the fusion power is produced through thermonuclear reactions and reactions between thermal ions and fast particles generated by neutral beam injection (NBI) heating or accelerated by electromagnetic wave heating in the ion cyclotron range of frequencies (ICRFs). To complement the experiments with 50/50 D/T mixtures maximizing thermonuclear reactivity, a scenario with dominant non-thermal reactivity has been developed and successfully demonstrated during the second JET deuterium-tritium campaign DTE2, as it was predicted to generate the highest fusion power in JET with a Be/W wall. It was performed in a 15/85 D/T mixture with pure D-NBI heating combined with ICRF heating at the fundamental deuterium resonance. In steady plasma conditions, a record 59 MJ of fusion energy has been achieved in a single pulse, of which 50.5 MJ were produced in a 5 s time window ( P _fus = 10.1 MW) with average Q = 0.33, confirming predictive modelling in preparation of the experiment. The highest fusion power in these experiments, P _fus = 12.5 MW with average Q = 0.38, was achieved over a shorter 2 s time window, with the period of sustainment limited by high-Z impurity accumulation. This scenario provides unique data for the validation of physics-based models used to predict D-T fusion power.
Published: 2023
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10. Stability analysis of alpha driven toroidal Alfvén eigenmodes observed in JET deuterium-tritium internal transport barrier plasmas

Author: M. Fitzgerald, R. Dumont, D. Keeling, J. Mailloux, S. Sharapov, M. Dreval, A. Figueiredo, R. Coelho, J. Ferreira, P. Rodrigues, F. Nabais, D. Borba, Ž. Štancar, G. Szepesi, R.A. Tinguely, P.G. Puglia, H.J.C. Oliver, V. Kiptily, M. Baruzzo, M. Lennholm, P. Siren, J. Garcia, C.F. Maggi, and JET Contributors
Subjects: JET DT, TAE, Alfvén, MHD, fast particle, ITB, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: A toroidal Alfvén eigenmode (TAE) has been observed to be driven by alpha particles in a JET deuterium-tritium internal transport barrier plasma. The observation occurred 50 ms after the removal of neutral beam heating (NBI). The mode is observed on magnetics, soft-xray, interferometry and reflectometry measurements. We present detailed stability calculations using a similar tool set validated during deuterium only discharges. These calculations strongly support the conclusion that the observed mode is a TAE, and that this mode was destabilized by alpha particles. Non-ideal effects from the bulk plasma are interpreted as responsible for suppressing the majority of TAEs which were also driven by alpha particles, but the modes that match the observations are predicted to be particularly weak for these non-ideal effects. This mode located far from the core on the outboard midplane is found to be driven by both trapped and passing particles despite alpha particles originating in the core.
Published: 2023
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11. Isotope mass scaling and transport comparison between JET Deuterium and Tritium L-mode plasmas

Author: T. Tala, A.E. Järvinen, C.F. Maggi, P. Mantica, A. Mariani, A. Salmi, I.S. Carvalho, A. Chomiczewska, E. Delabie, F. Devasagayam, J. Ferreira, W. Gromelski, N. Hawkes, L. Horvath, J. Karhunen, D. King, A. Kirjasuo, E. Kowalska-Strzeciwilk, S. Leerink, M. Lennholm, B. Lomanowski, M. Maslov, S. Menmuir, R.B. Morales, R. Sharma, H. Sun, K. Tanaka, and JET Contributors
Subjects: isotope mass scaling, Deuterium and Tritium, confinement and transport, JET, dimensionless scaling, heat and particle transport, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The dimensionless isotope mass scaling experiment between pure Deuterium and pure Tritium plasmas with matched $\rho^*$ , $\nu^*$ , β _n , q and $T_e/T_i$ has been achieved in JET L-mode with dominant electron heating (NBI+ohmic) conditions. 28% higher scaled energy confinement time $B_t\tau_{E,\mathrm{th}}/A$ is found in favour of the Tritium plasma. This can be cast in the form of the dimensionless energy confinement scaling law as $\Omega_i \tau_{E,\mathrm{th}} \sim A^{0.48 \pm 0.16}$ . This significant isotope mass scaling is consequently seen in the scaled one-fluid heat diffusion coefficient $A \chi_{\mathrm{eff}}/B_t$ which is around 50% lower in the Tritium plasma throughout the whole plasma radius. The isotope mass dependence in the particle transport channel is negligible, supported also by the perturbative particle transport analysis with gas puff modulation. The comparison of the edge particle fuelling or ionisation profiles from the EDGE2D-EIRENE simulations show that the absolute density differences that are necessary for the dimensionless match in the confined plasma dominate over any isotope mass dependencies of particle fuelling and ionization profiles at the plasma edge. Local GENE simulation results indicate a mild anti-gyroBohm effect at $\rho_\mathrm{tor}$ = 0.6 and thereby a small isotope mass dependence in favour of Tritium on heat transport and a negligible effect on particle transport. A significant fraction of the isotope scaling and reduced heat transport observed in the Tritium plasma is not captured in the GENE and ASTRA-TGLF-SAT2 simulations by simply changing the isotope mass for the same input profiles.
Published: 2023
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12. Experiments in high-performance JET plasmas in preparation of second harmonic ICRF heating of tritium in ITER

Author: M.J. Mantsinen, P. Jacquet, E. Lerche, D. Gallart, K. Kirov, P. Mantica, D. Taylor, D. Van Eester, M. Baruzzo, I. Carvalho, C.D. Challis, A. Dal Molin, E. Delabie, E. De La Luna, R. Dumont, P. Dumortier, J. Eriksson, D. Frigione, J. Garcia, L. Garzotti, C. Giroud, R. Henriques, J. Hobirk, A. Kappatou, Y. Kazakov, D. Keeling, D. King, V. Kiptily, M. Lennholm, P. Lomas, C. Lowry, C.F. Maggi, J. Mailloux, M. Maslov, S. Menmuir, I. Monakhov, R.B. Morales, C. Noble, M. Nocente, A. Patel, G. Pucella, C. Reux, D. Rigamonti, F. Rimini, A. Sheikh, S. Silburn, P. Siren, E.R. Solano, Z. Stancar, M. Tardocchi, and JET Contributors
Subjects: ICRF heating, fast ions, computational modelling, JET tokamak, H-mode hybrid plasma scenario, deuterium–tritium fuel mixture, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The reference ion cyclotron resonance frequency (ICRF) heating schemes for ITER deuterium–tritium (D-T) plasmas at the full magnetic field of 5.3 T are second harmonic heating of T and ^3 He minority heating. The wave-particle resonance location for these schemes coincide and are central at a wave frequency of 53 MHz at 5.3 T. Experiments have been carried out in the second major D-T campaign (DTE2) at JET, and in its prior D campaigns, to integrate these ICRF scenarios in JET high-performance plasmas and to compare their performance with the commonly used hydrogen (H) minority heating. In 50:50 D:T plasmas, up to 35% and 5% larger fusion power and diamagnetic energy content, respectively, were obtained with second harmonic heating of T as compared to H minority heating at comparable total input powers and gas injection rates. The core ion temperature was up to 30% and 20% higher with second harmonic T and ^3 He minority heating, respectively, with respect to H minority heating. These are favourable results for the use of these scenarios in ITER and future fusion reactors. According to modelling, adding ICRF heating to neutral beam injection using D and T beams resulted in a 10%–20% increase of on-axis bulk ion heating in the D-T plasmas due to its localisation in the plasma core. Central power deposition was confirmed with the break-in-slope and fast Fourier transform analysis of ion and electron temperature in response to ICRF modulation. The tail temperature of fast ICRF-accelerated tritons, their enhancement of the fusion yield and time behaviour as measured by an upgraded magnetic proton recoil spectrometer and neutral particle analyser were found in agreement with theoretical predictions. No losses of ICRF-accelerated ions were observed by fast ion detectors, which was as expected given the high plasma density of n _e ≈ 7–8 × 10 ^19 m ^−3 in the main heating phase that limited the formation of ICRF-accelerated fast ion tails. ^3 He was introduced in the machine by ^3 He gas injection, and the ^3 He concentration was measured by a high-resolution optical penning gauge in the sub-divertor region. The DTE2 experiments with ^3 He minority heating were carried with a low ^3 He concentration in the range of 2%–4% given the fact that the highest neutron rates with ^3 He minority heating in D plasmas were obtained at low ^3 He concentrations of ∼2%, which also coincided with the highest plasma diamagnetic energy content. In addition to ^3 He introduced by ^3 He gas injection, an intrinsic concentration of ^3 He of the order of 0.2%–0.4% was measured in D-T plasmas before ^3 He was introduced in the device, which is attributed to the radioactive decay of tritium to ^3 He. According to modelling, even such low intrinsic concentrations of ^3 He lead to significant changes in ICRF power partitioning during second harmonic heating of T due to absorption of up to 30% of the wave power by ^3 He.
Published: 2023
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13. L-H transition studies in tritium and deuterium–tritium campaigns at JET with Be wall and W divertor

Author: E.R. Solano, G. Birkenmeier, C. Silva, E. Delabie, J.C. Hillesheim, A. Baciero, I. Balboa, M. Baruzzo, A. Boboc, M. Brix, J. Bernardo, C. Bourdelle, I.S. Carvalho, P. Carvalho, C.D. Challis, M. Chernyshova, A. Chomiczewska, R. Coelho, I. Coffey, T. Craciunescu, E. de la Cal, E. de la Luna, R. Dumont, P. Dumortier, M. Fontana, J.M. Fontdecaba, L. Frassinetti, D. Gallart, J. Garcia, C. Giroud, W. Gromelski, R.B. Henriques, J. Hall, A. Ho, L.D. Horton, L. Horvath, P. Jacquet, I. Jepu, E. Joffrin, A. Kappatou, D.L. Keeling, D.B. King, V.G. Kiptily, K.K. Kirov, D. Kos, E. Kowalska-Strzęciwilk, M. Lennholm, E. Lerche, E. Litherland-Smith, A. Loarte, B. Lomanowski, P.J. Lomas, C.F. Maggi, J. Mailloux, M.J. Mantsinen, M. Maslov, A.G. Meigs, I. Monakhov, R.B. Morales, A.H. Nielsen, D. Nina, C. Noble, E. Pawelec, M. Poradzinski, G. Pucella, P. Puglia, D. Réfy, J. Juul Rasmussen, E. Righi, F.G. Rimini, T. Robinson, M. Sertoli, S.A. Silburn, G. Sips, P. Sirén, Ž. Štancar, H.J. Sun, G. Szepesi, D. Taylor, E. Tholerus, B. Thomas, G. Verdoolaege, P. Vincenzi, B. Viola, N. Vianello, T. Wilson, and JET Contributors
Subjects: L-H transition, power threshold, tokamaks, Tritium, DT, JET-ILW, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The recent deuterium–tritium campaign in JET-ILW (DTE2) has provided a unique opportunity to study the isotope dependence of the L-H power threshold in an ITER-like wall environment (Be wall and W divertor). Here we present results from dedicated L-H transition experiments at JET-ILW, documenting the power threshold in tritium and deuterium–tritium plasmas, comparing them with the matching deuterium and hydrogen datasets. From earlier experiments in JET-ILW it is known that as plasma isotopic composition changes from deuterium, through varying deuterium/hydrogen concentrations, to pure hydrogen, the value of the line averaged density at which the threshold is minimum, ${\bar n_{{\text{e}},{\text{min}}}}$ , increases, leading us to expect that ${\bar n_{{\text{e}},{\text{min}}}}$ (T) < ${\bar n_{{\text{e}},{\text{min}}}}$ (DT) < ${\bar n_{{\text{e}},{\text{min}}}}$ (D) < ${\bar n_{{\text{e}},{\text{min}}}}$ (H). The new power threshold data confirms these expectations in most cases, with the corresponding ordering of the minimum power thresholds. We present a comparison of this data to power threshold scalings, used for extrapolation to future devices such as ITER and DEMO.
Published: 2023
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14. Tritium removal from JET-ILW after T and D–T experimental campaigns

Author: D. Matveev, D. Douai, T. Wauters, A. Widdowson, I. Jepu, M. Maslov, S. Brezinsek, T. Dittmar, I. Monakhov, P. Jacquet, P. Dumortier, H. Sheikh, R. Felton, C. Lowry, D. Ciric, J. Banks, R. Buckingham, H. Weisen, L. Laguardia, G. Gervasini, E. de la Cal, E. Delabie, Z. Ghani, J. Gaspar, J. Romazanov, M. Groth, H. Kumpulainen, J. Karhunen, S. Knipe, S. Aleiferis, T. Loarer, A. Meigs, C. Noble, G. Papadopoulos, E. Pawelec, S. Romanelli, S. Silburn, E. Joffrin, E. Tsitrone, F. Rimini, C.F. Maggi, and JET Contributors
Subjects: JET-ILW, tritium retention, tritium removal, wall cleaning, DTE2, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: After the second Deuterium–Tritium Campaign (DTE2) in the JET tokamak with the ITER-Like Wall (ILW) and full tritium campaigns that preceded and followed after the DTE2, a sequence of fuel recovery methods was applied to promote tritium removal from wall components. The sequence started with several days of baking of the main chamber walls at 240 °C and at 320 °C. Subsequently, baking was superimposed with Ion-Cyclotron Wall Conditioning (ICWC) and Glow Discharge Conditioning (GDC) cleaning cycles in deuterium. Diverted plasma operation in deuterium with different strike point configurations, including a Raised Inner Strike Point (RISP) configuration, and with different plasma heating—Ion Cyclotron Resonance Frequency (ICRF) and Neutral Beam Injection (NBI)—concluded the cleaning sequence. Tritium content in plasma and in the pumped gas was monitored throughout the experiment. The applied fuel recovery methods allowed reducing the residual tritium content in deuterium NBI-heated plasmas to about 0.1% as deduced from neutron rate measurements. This value is well below the requirement of 1% set by the maximum 14 MeV fusion neutron budget allocated in the ensuing deuterium plasma campaign. The quantified tritium removal over the course of the experiment was $\left( {13.4 \pm 0.7} \right) \times {10^{22}}$ atoms or $\left( {0.67 \pm 0.03} \right)$ g with ∼58% attributed to baking, ∼12.5% to ICWC, ∼26% to GDC, and ∼3.5% to first low power RISP plasmas. The experimentally estimated amount of removed tritium is in good agreement with long-term tritium accounting by the JET tritium reprocessing plant, in which the unaccounted amount was reduced by $0.71$ g after the cleaning experiment.
Published: 2023
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15. Effect of the isotope mass on pedestal structure, transport and stability in D, D/T and T plasmas at similar β N and gas rate in JET-ILW type I ELMy H-modes

Author: L. Frassinetti, C. Perez von Thun, B. Chapman-Oplopoiou, H. Nyström, M. Poradzinski, J.C. Hillesheim, L. Horvath, C.F. Maggi, S. Saarelma, A. Stagni, G. Szepesi, A. Bleasdale, A. Chomiczewska, R.B. Morales, M. Brix, P. Carvalho, D. Dunai, A.R. Field, J.M. Fontdecaba, H.J. Sun, D.B. King, D. Kos, E. Kowalska, B. Labit, M. Lennholm, S. Menmuir, E. Rachlew, D.I. Refy, P.A. Schneider, E.R. Solano, N. Vianello, M. Vécsei, and JET Contributors
Subjects: pedestal, stability, tritium, deuterium/tritium, JET-ILW, isotope effect, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The work describes the pedestal structure, transport and stability in an effective mass ( A _eff ) scan from pure deuterium to pure tritium plasmas using a type I ELMy H-mode dataset in which key parameters that affect the pedestal behaviour (normalized pressure, ratio of the separatrix density to the pedestal density, pedestal ion Larmor radius, pedestal collisionality and rotation) are kept as constant as possible. Experimental results show a significant increase of the density at the pedestal top with increasing A _eff , a modest reduction in the temperature and an increase in the pressure. The variations in the pedestal heights are mainly due to a change in the pedestal gradients while only small differences are observed in the pedestal width. A clear increase in the pedestal density and pressure gradients are observed from deuterium to tritium. The experimental results suggest a reduction of the pedestal inter-edge localized mode (inter-ELM) transport from deuterium to tritium. The reduction is likely in the pedestal inter-ELM particle transport, as suggested by the clear increase of the pedestal density gradients. The experimental results suggest also a possible reduction of the pedestal inter-ELM heat transport, however, the large experimental uncertainties do not allow conclusive claims on the heat diffusivity. The clear experimental reduction of η _e (the ratio between density and temperature gradient lengths) in the middle/top of the pedestal with increasing A _eff suggests that there may be a link between increasing A _eff and the reduction of electron scale turbulent transport. From the modelling point of view, an initial characterization of the behaviour of pedestal microinstabilities shows that the tritium plasma is characterized by growth rates lower than the deuterium plasmas. The pedestal stability of peeling-ballooning modes is assessed with both ideal and resistive magnetohydrodynamics (MHD). No significant effect of the isotope mass on the pedestal stability is observed using ideal MHD. Instead, resistive MHD shows a clear increase of the stability with increasing isotope mass. The resistive MHD results are in reasonable agreement with the experimental results of the normalized pedestal pressure gradient. The experimental and modelling results suggest that the main candidates to explain the change in the pedestal are a reduction in the inter-ELM transport and an improvement of the pedestal stability from deuterium to tritium.
Published: 2023
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16. Isotope physics of heat and particle transport with tritium in JET-ILW type-I ELMy H-mode plasmas

Author: P.A. Schneider, C. Angioni, F. Auriemma, N. Bonanomi, T. Görler, R. Henriques, L. Horvath, D. King, R. Lorenzini, H. Nyström, M. Maslov, J. Ruiz, G. Szepesi, C.D. Challis, A. Chomiczewska, E. Delabie, J.M. Fontdecaba, L. Frassinetti, J. Garcia, C. Giroud, J. Hillesheim, J. Hobirk, A. Kappatou, D.L. Keeling, E. Kowalska-Strzeciwilk, M. Lennholm, B. Lomanowski, T. Luda di Cortemiglia, C.F. Maggi, S. Menmuir, G. Pucella, A. Thorman, and JET Contributors
Subjects: H-mode, tritium, heat transport, particle transport, stability, isotopes, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: As part the DTE2 campaign in the JET tokamak, we conducted a parameter scan in T and D-T complementing existing pulses in H and D. For the different main ion masses, type-I ELMy H-modes at fixed plasma current and magnetic field can have the pedestal pressure varying by a factor of 4 and the total pressure changing from $\beta_{\mathrm{N}} = 1.0$ to 3.0. We investigated the pedestal and core isotope mass dependencies using this extensive data set. The pedestal shows a strong mass dependence on the density, which influences the core due to the strong coupling between both plasma regions. To better understand the causes for the observed isotope mass dependence in the pedestal, we analysed the interplay between heat and particle transport and the edge localised mode (ELM) stability. For this purpose, we developed a dynamic ELM cycle model with basic transport assumptions and a realistic neutral penetration. The temporal evolution and resulting ELM frequency introduce an additional experimental constraint that conventional quasi-stationary transport analysis cannot provide. Our model shows that a mass dependence in the ELM stability or in the transport alone cannot explain the observations. One requires a mass dependence in the ELM stability as well as one in the particle sources. The core confinement time increases with pedestal pressure for all isotope masses due to profile stiffness and electromagnetic turbulence stabilisation. Interestingly, T and D-T plasmas show an improved core confinement time compared to H and D plasmas even for matched pedestal pressures. For T, this improvement is largely due to the unique pedestal composition of higher densities and lower temperatures than H and D. With a reduced gyroBohm factor at lower temperatures, more turbulent drive in the form of steeper gradients is required to transport the same amount of heat. This picture is supported by quasilinear flux-driven modelling using TGLF -SAT2 within Astra . With the experimental boundary condition TGLF -SAT2 predicts the core profiles well for gyroBohm heat fluxes ${\gt}15$ , however, overestimates the heat and particle transport closer to the turbulent threshold.
Published: 2023
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17. Overview of interpretive modelling of fusion performance in JET DTE2 discharges with TRANSP

Author: Ž. Štancar, K.K. Kirov, F. Auriemma, H.-T. Kim, M. Poradziński, R. Sharma, R. Lorenzini, Z. Ghani, M. Gorelenkova, F. Poli, A. Boboc, S. Brezinsek, P. Carvalho, F.J. Casson, C.D. Challis, E. Delabie, D. Van Eester, M. Fitzgerald, J.M. Fontdecaba, D. Gallart, J. Garcia, L. Garzotti, C. Giroud, A. Kappatou, Ye.O. Kazakov, D.B. King, V.G. Kiptily, D. Kos, E. Lerche, E. Litherland-Smith, C.F. Maggi, P. Mantica, M.J. Mantsinen, M. Maslov, S. Menmuir, M. Nocente, H.J.C. Oliver, S.E. Sharapov, P. Sirén, E.R. Solano, H.J. Sun, G. Szepesi, and JET Contributors
Subjects: deuterium-tritium plasma, integrated modelling, fusion performance, JET, TRANSP, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: In the paper we present an overview of interpretive modelling of a database of JET-ILW 2021 D-T discharges using the TRANSP code. The main aim is to assess our capability of computationally reproducing the fusion performance of various D-T plasma scenarios using different external heating and D-T mixtures, and to understand the performance driving mechanisms. We find that interpretive simulations confirm a general power-law relationship between increasing external heating power and fusion output, which is supported by absolutely calibrated neutron yield measurements. A comparison of measured and computed D-T neutron rates shows that the calculations’ discrepancy depends on the absolute neutron yield. The calculations are found to agree well with measurements for higher performing discharges with external heating power above ∼20 $\mathrm{MW}$ , while low-neutron shots display an average discrepancy of around +40% compared to measured neutron yields. A similar trend is found for the ratio between thermal and beam-target fusion, where larger discrepancies are seen in shots with dominant beam-driven performance. We compare the observations to studies of JET-ILW D discharges, to find that on average the fusion performance is well modelled over a range of heating power, although an increased unsystematic deviation for lower-performing shots is observed. The ratio between thermal and beam-induced D-T fusion is found to be increasing weakly with growing external heating power, with a maximum value of $\gtrsim$ 1 achieved in a baseline scenario experiment. An evaluation of the fusion power computational uncertainty shows a strong dependence on the plasma scenario type and fusion drive characteristics, varying between ±25% and 35%. D-T fusion alpha simulations show that the ratio between volume-integrated electron and ion heating from alphas is $\lesssim$ 10 for the majority of analysed discharges. Alphas are computed to contribute between ∼15% and 40% to the total electron heating in the core of highest performing D-T discharges. An alternative workflow to TRANSP was employed to model JET D-T plasmas with the highest fusion yield and dominant non-thermal fusion component because of the use of fundamental radio-frequency heating of a large minority in the scenario, which is calculated to have provided ∼10% to the total fusion power.
Published: 2023
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18. Isotope mass dependence of pedestal transport in JET H-mode plasmas

Author: I. Predebon, D.R. Hatch, L. Frassinetti, L. Horvath, S. Saarelma, B. Chapman-Oplopoiou, T. Görler, C.F. Maggi, and JET Contributors
Subjects: pedestal, isotope effect, transport, gyrokinetics, JET-ILW, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: We present a comparative transport analysis of the isotope mass dependence in the pedestal of two pairs of deuterium/hydrogen type I ELMy H-mode discharges in JET with ITER-like wall, one characterized by the same input power, the other one by the same stored energy. The investigation, carried out using the gyrokinetic code GENE, focuses on the steep profile region of the pedestal. While large wavenumber modes mainly contribute to the electron heat flux and are scarcely influenced by the main gas isotope, an effect of the ion mass in agreement with the experimental (so called anti-gyro-Bohm) scaling is revealed in the low wavenumber range. In this context, the major role played by the ${E\!\times\!B}$ shear in regulating the ion-temperature-gradient turbulence is analyzed in some detail. The competing level of turbulent and neoclassical transport is quantified to shed light on the experimental features of the pedestal profiles at different ion mass, with the particle transport found to be consistent with a higher pedestal top density for increasing isotope masses, and the heat transport shown to match the roughly unaltered observed temperature profiles.
Published: 2023
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19. Isotope effects on intrinsic rotation in hydrogen, deuterium and tritium plasmas

Author: M.F.F. Nave, E. Delabie, J. Ferreira, J. Garcia, D. King, M. Lennholm, B. Lomanowski, F. Parra, P.R. Fernandez, J. Bernardo, M. Baruzzo, M. Barnes, F. Casson, J.C. Hillesheim, A. Hubber, E. Joffrin, A. Kappatou, C.F. Maggi, A. Mauriya, L. Meneses, M. Romanelli, F. Salzedas, and JET Contributors
Subjects: intrinsic rotation, isotope mass, tritium plasmas, Ohmic confinement, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: The isotope effect on intrinsic rotation was studied at the Joint European Torus (JET) tokamak. With the unique capability of JET to operate with tritium (T), for the first time, experiments in hydrogen (H), deuterium (D) and T in Ohmic plasmas were compared. Two rotation reversals per isotope type are observed in plasma density scans spanning the linear and the saturated Ohmic confinement regimes. A clear isotope mass dependence is observed at the higher densities. The magnitude of the core rotation was found to depend on isotope mass, with stronger co-current rotation observed in H. Change on intrinsic rotation characteristics coexist with a stronger thermal energy confinement in T.
Published: 2023
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20. Predictive JET current ramp-up modelling using QuaLiKiz-neural-network

Author: A. Ho, J. Citrin, C.D. Challis, C. Bourdelle, F.J. Casson, J. Garcia, J. Hobirk, A. Kappatou, D.L. Keeling, D.B. King, F. Koechl, E. Lerche, C.F. Maggi, J. Mailloux, and JET Contributors
Subjects: integrated modelling, tokamak, current ramp-up, surrogate model, isotope effect, impurity transport, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract: This work applies the coupled JINTRAC and QuaLiKiz-neural-network (QLKNN) model on the ohmic current ramp-up phase of a JET D discharge. The chosen scenario exhibits a hollow $T_\mathrm{e}$ profile attributed to core impurity accumulation, which is observed to worsen with the increasing fuel ion mass from D to T. A dynamic D simulation was validated, evolving j , $n_\mathrm{e}$ , $T_\mathrm{e}$ , $T_\mathrm{i}$ , n _Be , n _Ni , and n _W for 7.25 s along with self-consistent equilibrium calculations, and was consequently extended to simulate a pure T plasma in a predict-first exercise. The light impurity (Be) accounted for Z _eff while the heavy impurities (Ni, W) accounted for P _rad . This study reveals the role of transport on the $T_\mathrm{e}$ hollowing, which originates from the isotope effect on the electron-ion energy exchange affecting $T_\mathrm{i}$ . This exercise successfully affirmed isotopic trends from previous H experiments and provided engineering targets used to recreate the D q -profile in T experiments, demonstrating the potential of neural network surrogates for fast routine analysis and discharge design. However, discrepancies were found between the impurity transport behaviour of QuaLiKiz and QLKNN, which lead to notable $T_\mathrm{e}$ hollowing differences. Further investigation into the turbulent component of heavy impurity transport is recommended.
Published: 2023
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21. Use of the Culham He model He II atomic data in JET EDGE2D-EIRENE simulations

Author: K.D. Lawson, M. Groth, D. Harting, S. Menmuir, D. Reiter, K.M. Aggarwal, S. Brezinsek, I.H. Coffey, G. Corrigan, F.P. Keenan, C.F. Maggi, A.G. Meigs, M.G. O'Mullane, J. Simpson, and S. Wiesen
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Published: 2021
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22. Main chamber wall plasma loads in JET-ITER-like wall at high radiated fraction

Author: C. Guillemaut, P. Drewelow, G.F. Matthews, A.S. Kukushkin, R.A. Pitts, P. Abreu, S. Brezinsek, M. Brix, P. Carman, R. Coelho, S. Devaux, J. Flanagan, C. Giroud, D. Harting, C.G. Lowry, C.F. Maggi, F. Militello, C. Perez Von Thun, E.R. Solano, A. Widdowson, S. Wiesen, M. Wischmeier, and D. Wood
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Abstract: Future tokamak reactors of conventional design will require high levels of exhaust power dissipation (more than 90% of the input power) if power densities at the divertor targets are to remain compatible with active cooling. Impurity seeded H-mode discharges in JET-ITER-like Wall (ILW) have reached a maximum radiative fraction (Frad) of ∼75%. Divertor Langmuir probe (LP) measurements in these discharges indicate, however, that less than ∼3% of the thermal plasma power reaches the targets, suggesting a missing channel for power loss. This paper presents experimental evidence from limiter LP for enhanced cross-field particle fluxes on the main chamber walls at high Frad. In H-mode nitrogen-seeded discharges with Frad increasing from ∼30% to up to ∼75%, the main chamber wall particle fluence rises by a factor ∼3 while the divertor plasma fluence drops by one order of magnitude. Contribution of main chamber wall particle losses to detachment, as suggested by EDGE2D-EIRENE modeling, is not sufficient to explain the magnitude of the observed divertor fluence reduction. An intermediate detached case obtained at Frad ∼ 60% with neon seeding is also presented. Heat loads were measured using the main chamber wall thermocouples. Comparison between thermocouple and bolometry measurements shows that the fraction of the input power transported to the main chamber wall remains below ∼5%, whatever the divertor detachment state is. Main chamber sputtering of beryllium by deuterium is reduced in detached conditions only on the low field side. If the fraction of power exhaust dissipated to the main chamber wall by cross-field transport in future reactors is similar to the JET-ILW levels, wall plasma power loading should not be an issue. However, other contributions such as charge exchange may be a problem.
Published: 2017
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23. Possible influence of near SOL plasma on the H-mode power threshold

Author: A.V. Chankina, E. Delabie, G. Corrigan, C.F. Maggi, H. Meyer, and JET Contributors
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Abstract: A strong effect of divertor configuration on the threshold power for the L-H transition (PLH) was observed in recent JET experiments in the new ITER-like Wall (ILW) [1–3]. Following a series of EDGE2D-EIRENE code simulations with Be impurity and drifts a possible mechanism for the PLH variation with the divertor geometry is proposed. Both experiment and code simulations show that in the configuration with lower neutral recycling near the outer strike point (OSP), electron temperature (Te) peaks near the OSP prior to the L-H transition, while in the configuration with higher OSP recycling Te peaks further out in the scrape-off layer (SOL) and the plasma stays in the L-mode at the same input power. Code results show large positive radial electric field (Er) in the near SOL under lower recycling conditions leading to a large E×B shear across the separatrix which may trigger earlier (at lower input power) edge turbulence suppression and lower PLH. Suppressed Te‘s at OSP in configurations with strike points on vertical targets (VT) were observed earlier and explained by a geometrical effect of neutral recycling near this particular position, whereas in configurations with strike points on horizontal targets (HT) the OSP appears to be more open for neutrals (see e.g. review paper [4]). Keywords: Plasma-materials interaction, Plasma properties, H-mode, SOL, Divertor, JET, EDGE2D-EIRENE
Published: 2017
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24. Comparative H-mode density limit studies in JET and AUG

Author: A. Huber, M. Bernert, S. Brezinsek, A.V. Chankin, G. Sergienko, V. Huber, S. Wiesen, P. Abreu, M.N.A. Beurskens, A. Boboc, M. Brix, G. Calabrò, D. Carralero, E. Delabie, T. Eich, H.G. Esser, M. Groth, C. Guillemaut, S. Jachmich, A. Järvinen, E. Joffrin, A. Kallenbach, U. Kruezi, P. Lang, Ch. Linsmeier, C.G. Lowry, C.F. Maggi, G.F. Matthews, A.G. Meigs, Ph. Mertens, F. Reimold, J. Schweinzer, G. Sips, M. Stamp, E. Viezzer, M. Wischmeier, and H. Zohm
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Abstract: Identification of the mechanisms for the H-mode density limit in machines with fully metallic walls, and their scaling to future devices is essential to find for these machines the optimal operational boundaries with the highest attainable density and confinement. Systematic investigations of H-mode density limit plasmas in experiments with deuterium external gas fuelling have been performed on machines with fully metallic walls, JET and AUG and results have been compared with one another.Basically, the operation phases are identical for both tokamaks: the stable H-mode phase, degrading H-mode phase, breakdown of the H-mode with energy confinement deterioration usually accompanied by a dithering cycling phase, followed by the l-mode phase. The observed H-mode density limit on both machines is found close to the Greenwald limit (n/nGW=0.8–1.1 in the observed magnetic configurations). The similar behavior of the radiation on both tokamaks demonstrates that the density limit (DL) is neither related to additional energy losses from the confined region by radiation, nor to an inward collapse of the hot discharge core induced by overcooling of the plasma periphery by radiation.It was observed on both machines that detachment, as well as the X-point MARFE itself, does not trigger a transition in the confinement regime and thus does not present a limit on the plasma density. It is the plasma confinement, most likely determined by edge parameters, which is ultimately responsible for the transition from H- to l-mode.The measured Greenwald fractions are found to be consistent with the predictions from different theoretical models [16,30] based on MHD instability theory in the near-SOL. Keywords: Density limit, H-mode, Detachment, Greenwald fraction, JET, ASDEX Upgrade
Published: 2017
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25. A study of the atomic and molecular power loss terms in EDGE2D-EIRENE simulations of JET ITER-like wall L-mode discharges

Author: K.D. Lawson, M. Groth, D. Harting, S. Menmuir, D. Reiter, S. Brezinsek, G. Corrigan, P. Drewelow, C.F. Maggi, A.G. Meigs, J. Simpson, M.F. Stamp, S. Wiesen, and Contributors
Subjects: Nuclear engineering. Atomic power, TK9001-9401
Abstract: A discrepancy in the divertor radiated powers between EDGE2D-EIRENE simulations and JET-ILW experiments employing a set of NBI-heated L-mode discharges with step-wise density variation is investigated. The analysis shows the importance of the contributions from the deuterium fuel to the divertor radiated power, making these discharges ideal for this study. Molecular radiation losses from D2 molecules have been included for the first time and the present simulations allow the atomic and molecular electron power loss terms in EIRENE to be independently scaled in order to understand their importance in determining the simulated electron temperatures and distribution of radiated power. PSI-22 keywords: Divertor modelling, Divertor diagnostic, EDGE2D, JET, ILW
Published: 2017
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26. Recent progress in L-H transition studies at JET: tritium, helium, hydrogen and deuterium

Author: E.R. Solano, E. Delabie, G. Birkenmeier, C. Silva, J.C. Hillesheim, P. Vincenzi, A.H. Nielsen, J.Juul Rasmussen, A. Baciero, S. Aleiferis, I. Balboa, A. Boboc, C. Bourdelle, I.S. Carvalho, P. Carvalho, M. Chernyshova, R. Coelho, T. Craciunescu, R. Dumont, P. Dumortier, E.de la Luna, J. Flanagan, M. Fontana, J.M. Fontdecaba, L. Frassinetti, D. Gallart, J. Garcia, E. Giovannozzi, C. Giroud, W. Gromelski, R. Henriques, L. Horvath, P. Jacquet, I. Jepu, A. Kappatou, D.L. Keeling, D. King, E. Kowalska-Strzęciwilk, M. Lennholm, E. Lerche, E. Litherland-Smith, V. Kiptily, K. Kirov, A. Loarte, B. Lomanowski, C.F. Maggi, M.J. Mantsinen, A. Manzanares, M. Maslov, A.G. Meigs, I. Monakhov, R.B. Morales, D. Nina, C. Noble, V. Parail, F.Parra Diaz, E. Pawelec, G. Pucella, D. Réfy, E. Righi-Steele, F.G. Rimini, T. Robinson, S. Saarelma, M. Sertoli, A. Shaw, S. Silburn, P. Sirén, Ž. Štancar, H. Sun, G. Szepesi, D. Taylor, E. Tholerus, S. Vartanian, G. Verdoolaege, B. Viola, H. Weisen, T. Wilson, JET Contributors, and JET Contributors
Subjects: Nuclear and High Energy Physics, Physics::Plasma Physics, tritium, L–H transition, Physics::Atomic Physics, helium, isotope, Condensed Matter Physics, L-H transition
Abstract: We present an overview of results from a series of L–H transition experiments undertaken at JET since the installation of the ITER-like-wall (JET-ILW), with beryllium wall tiles and a tungsten divertor. Tritium, helium and deuterium plasmas have been investigated. Initial results in tritium show ohmic L–H transitions at low density and the power threshold for the L–H transition (P LH) is lower in tritium plasmas than in deuterium ones at low densities, while we still lack contrasted data to provide a scaling at high densities. In helium plasmas there is a notable shift of the density at which the power threshold is minimum ( n ¯ e , min ) to higher values relative to deuterium and hydrogen references. Above n ¯ e , min (He) the L–H power threshold at high densities is similar for D and He plasmas. Transport modelling in slab geometry shows that in helium neoclassical transport competes with interchange-driven transport, unlike in hydrogen isotopes. Measurements of the radial electric field in deuterium plasmas show that E r shear is not a good indicator of proximity to the L–H transition. Transport analysis of ion heat flux in deuterium plasmas show a non-linearity as density is decreased below n ¯ e , min . Lastly, a regression of the JET-ILW deuterium data is compared to the 2008 ITPA scaling law.
Published: 2022

27. The dependence of confinement on the isotope mass in the core and the edge of AUG and JET-ILW H-mode plasmas

Author: P.A. Schneider, C. Angioni, L. Frassinetti, L. Horvath, M. Maslov, F. Auriemma, M. Cavedon, C.D. Challis, E. Delabie, M.G. Dunne, J.M. Fontdecaba, J. Hobirk, A. Kappatou, D.L. Keeling, B. Kurzan, M. Lennholm, B. Lomanowski, C.F. Maggi, R.M. McDermott, T. Pütterich, A. Thorman, M. Willensdorfer, null the ASDEX Upgrade Team, null the EUROfusion MST1 Team, null JET Contributors, Schneider, P, Angioni, C, Frassinetti, L, Horvath, L, Maslov, M, Auriemma, F, Cavedon, M, Challis, C, Delabie, E, Dunne, M, Climent, J, Hobirk, J, Kappatou, A, Keeling, D, Kurzan, B, Lennholm, M, Lomanowski, B, Maggi, C, Mcdermott, R, Putterich, T, Thorman, A, Willensdorfer, M, ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, EUROfusion MST1 Team, and JET Contributors
Subjects: Nuclear and High Energy Physics, 0103 physical sciences, pedestal stability, 010306 general physics, Condensed Matter Physics, 01 natural sciences, tokamak, heat transport, quasilinear modelling, 010305 fluids & plasmas, isotope effect
Abstract: Experiments in ASDEX Upgrade (AUG) and JET with the ITER-like wall (JET-ILW) are performed to separate the pedestal and core contributions to confinement in H-modes with different main ion masses. A strong isotope mass dependence in the pedestal is found which is enhanced at high gas puffing. This is because the ELM type changes when going from D to H for matched engineering parameters, which is likely due to differences in the inter ELM transport with isotope mass. The pedestal can be matched in H and D plasmas by varying only the triangularity and keeping the engineering parameters relevant for core transport the same. With matched pedestals Astra/TGLF (Sat1geo) core transport simulations predict the experimental profiles equally well for H and D. These core transport simulations show a negligible mass dependence and no gyro-Bohm scaling is observed. However, to match the experimental observations at medium β it is required to take the fast-ion dilution and rotation into account. This is not enough for high β plasmas where for the first time a profile match between H and D plasmas was achieved experimentally. Under these conditions quasilinear modelling with TGLF over predicts the transport in the core of H and D plasmas alike.
Published: 2022
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28. Effect of resistivity on the pedestal MHD stability in JET

Author: H. Nyström, L. Frassinetti, S. Saarelma, G.T.A. Huijsmans, C. Perez von Thun, C.F. Maggi, J.C. Hillesheim, and JET contributors
Subjects: Nuclear and High Energy Physics, Condensed Matter Physics
Abstract: The ELM triggering mechanism in tokamaks is not yet fully understood. For example, in the JET tokamak with ITER-like wall (commonly called JET-ILW), the ELMs are sometimes triggered before the ideal peeling-ballooning (PB) boundary is reached. This typically occurs for shots with high input power and high gas rate. The discrepancy between model and experiment has in previous works been clearly correlated with the relative shift between the electron temperature and density pedestals. The discrepancy has also been correlated with the resistivity in the middle-bottom of the pedestal. The present work shows that resistive MHD can have a significant impact on the PB stability of JET pedestals. The inclusion of resistivity removes the correlation between the discrepancy from the PB stability and the relative shift (the difference between the position of the electron temperature and density pedestals) and significantly improves the agreement between PB model and experimental results. The work also shows that the key parameter is the resistivity at the pedestal bottom, near the separatrix, while the resistivity near the middle/top of the pedestal has a negligible effect on the PB stability of JET plasmas.
Published: 2022

29. The role of ETG modes in JET–ILW pedestals with varying levels of power and fuelling

Author: B. Chapman-Oplopoiou, D.R. Hatch, A.R. Field, L. Frassinetti, J.C. Hillesheim, L. Horvath, C.F. Maggi, J.F. Parisi, C.M. Roach, S. Saarelma, and J. Walker
Subjects: Nuclear and High Energy Physics, Condensed Matter Physics
Abstract: We present the results of GENE gyrokinetic calculations based on a series of JET–ITER-like-wall (ILW) type I ELMy H-mode discharges operating with similar experimental inputs but at different levels of power and gas fuelling. We show that turbulence due to electron-temperature-gradient (ETGs) modes produces a significant amount of heat flux in four JET–ILW discharges, and, when combined with neoclassical simulations, is able to reproduce the experimental heat flux for the two low gas pulses. The simulations plausibly reproduce the high-gas heat fluxes as well, although power balance analysis is complicated by short ELM cycles. By independently varying the normalised temperature gradients ( ω T e ) and normalised density gradients ( ω n e ) around their experimental values, we demonstrate that it is the ratio of these two quantities η e = ω T e / ω n e that determines the location of the peak in the ETG growth rate and heat flux spectra. The heat flux increases rapidly as η e increases above the experimental point, suggesting that ETGs limit the temperature gradient in these pulses. When quantities are normalised using the minor radius, only increases in ω T e produce appreciable increases in the ETG growth rates, as well as the largest increases in turbulent heat flux which follow scalings similar to that of critical balance theory. However, when the heat flux is normalised to the electron gyro-Bohm heat flux using the temperature gradient scale length L T e , it follows a linear trend in correspondence with previous work by different authors.
Published: 2022

30. The power threshold of H-mode access in mixed hydrogen–tritium and pure tritium plasmas at JET with ITER-like wall

Author: G. Birkenmeier, E.R. Solano, E. Lerche, D. Taylor, D. Gallart, M.J. Mantsinen, E. Delabie, I.S. Carvalho, P. Carvalho, E. Pawelec, J.C. Hillesheim, F. Parra Diaz, C. Silva, S. Aleiferis, J. Bernardo, A. Boboc, D. Douai, E. Litherland-Smith, R. Henriques, K.K. Kirov, C.F. Maggi, J. Mailloux, M. Maslov, F.G. Rimini, S.A. Silburn, P. Sirén, H. Weisen, JET Contributors, and Barcelona Supercomputing Center
Subjects: Nuclear and High Energy Physics, Física::Física de fluids [Àrees temàtiques de la UPC], Isòtops, L–H transition, Tritium plasmas, Paper, magnetic confinement fusion, fusion plasmas, L-H transition, JET tokamak, tritium plasmas, Tritium, Condensed Matter Physics, jet tokamak, ddc, Physics::Plasma Physics, Fusion plasmas, Physics::Space Physics, Magnetic confinement fusion, Physics::Accelerator Physics, Tokamaks, l-h transition
Abstract: The heating power to access the high confinement mode (H-mode), PLH, scales approximately inversely with the isotope mass of the main ion plasma species as found in (protonic) hydrogen, deuterium and tritium plasmas in many fusion facilities over the last decades. In first dedicated L–H transition experiments at the Joint European Torus (JET) tokamak facility with the ITER-like wall (ILW), the power threshold, PLH, was studied systematically in plasmas of pure tritium and hydrogen–tritium mixtures at a magnetic field of 1.8 T and a plasma current of 1.7 MA in order to assess whether this scaling still holds in a metallic wall device. The measured power thresholds, PLH, in Ohmically heated tritium plasmas agree well with the expected isotope scaling for metallic walls and the lowest power threshold was found in Ohmic phases at low density. The measured power thresholds in ion cyclotron heated plasmas of pure tritium or hydrogen–tritium mixtures are significantly higher than the expected isotope mass scaling due to higher radiation levels. However, when the radiated power is taken into account, the ion cyclotron heated plasmas exhibit similar power thresholds as a neutral beam heated plasma, and are close to the scaling. The tritium plasmas in this study tended to higher electron heating fractions and, when heated with ion cyclotron waves, to relatively higher radiation fractions compared to other isotopes potentially impeding access to sustained H-modes. The authors thank P.A. Schneider, F. Ryter, A. Nielsen, and A. Kappatou for fruitful discussions and for help with data analysis tools. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom Research and Training Programme 2014–2018 and 2019–2020 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. G. Birkenmeier received funding from the Helmholtz Association under Grant No. VH-NG-1350. Peer Reviewed "Article signat per 27 autors/es: G. Birkenmeier, E.R. Solano, E. Lerche, D. Taylor, D. Gallart, M.J. Mantsinen, E. Delabie, I.S. Carvalho, P. Carvalho, E. Pawelec, J.C. Hillesheim, F. Parra Diaz, C. Silva, S. Aleiferis, J. Bernardo, A. Boboc, D. Douai, E. Litherland-Smith, R. Henriques, K.K. Kirov, C.F. Maggi, J. Mailloux, M. Maslov, F.G. Rimini, S.A. Silburn, P. Sirén, H. Weisen and JET Contributors"
Published: 2022

31. Microtearing modes as the source of magnetic fluctuations in the JET pedestal

Author: Gabriele Merlo, C.F. Maggi, C. Perez von Thun, A. R. Field, Craig Michoski, Frank Jenko, C. Giroud, Colin Roach, J. C. Hillesheim, M. J. Pueschel, D. Jarema, David Hatch, Swadesh M Mahajan, Ehab Hassan, Michael Kotschenreuther, Lorenzo Frassinetti, Samuli Saarelma, Jet Contributors, and JET Contributors
Subjects: Physics, Nuclear and High Energy Physics, Jet (fluid), Toroid, FOS: Physical sciences, Collisionality, Condensed Matter Physics, 01 natural sciences, Physics - Plasma Physics, 010305 fluids & plasmas, Computational physics, Plasma Physics (physics.plasm-ph), Pedestal, Collision frequency, Physics::Plasma Physics, Dispersion relation, 0103 physical sciences, Gyrokinetics, Electron temperature, 010306 general physics
Abstract: We report on a detailed study of magnetic fluctuations in the JET pedestal, employing basic theoretical considerations, gyrokinetic simulations, and experimental fluctuation data to establish the physical basis for their origin, role, and distinctive characteristics. We demonstrate quantitative agreement between gyrokinetic simulations of microtearing modes (MTMs) and two magnetic frequency bands with corresponding toroidal mode numbers n = 4 and 8. Such disparate fluctuation scales, with substantial gaps between toroidal mode numbers, are commonly observed in pedestal fluctuations. Here we provide a clear explanation, namely the alignment of the relevant rational surfaces (and not others) with the peak in the ω * profile, which is localized in the steep gradient region of the pedestal. We demonstrate that a global treatment is required to capture this effect. Nonlinear simulations suggest that the MTM fluctuations produce experimentally-relevant transport levels and saturate by relaxing the background electron temperature gradient, slightly downshifting the fluctuation frequencies from the linear predictions. Scans in collisionality are compared with a simple MTM dispersion relation. At the experimental points considered, MTM growth rates can either increase or decrease with collision frequency depending on the parameters thus defying any simple characterization of collisionality dependence.
Published: 2020

32. The role of the current profile in the improved H-mode scenario in ASDEX Upgrade

Author: J Stober, A.C.C Sips, C Angioni, C.B Forest, O Gruber, J Hobirk, L.D Horton, C.F Maggi, M Maraschek, P Martin, P.J. Mc Carthy, V Mertens, Y.-S Na, M Reich, A Stäbler, G Tardini, H Zohm, the ASDEX Upgrade Team, and ASDEX Upgrade Team
Subjects: Nuclear and High Energy Physics, Materials science, Safety factor, Relaxation (NMR), Phase (waves), Plasma, Mechanics, Condensed Matter Physics, Kinetic energy, Pedestal, ASDEX Upgrade, Physics::Plasma Physics, Atomic physics, Current (fluid)
Abstract: Recent studies at ASDEX Upgrade aim to further characterize and understand the physics of the improved H-mode scenario. The main focus is on the influence of the ramp-up phase of the plasma current and heating on energy confinement and MHD-activity during the subsequent flat-top phase. Depending on the ramp-up scenario two different stationary plasmas can be generated, which show different equilibrated current profiles, although external control parameters are the same in the flat-top phase. The difference of the current profiles in the flat-top phase seems to be due to different MHD-modes. These MHD-modes set in during relaxation of the current profile, which itself depends on the ramp-up scenario. Also the stored energy is different in the two cases as is the peaking of the temperature profiles.Three mechanisms seem to play a role in linking the observed changes in MHD-behaviour and current profile to the changes of the kinetic profiles: the increased transport due to the MHD-modes themselves, the variation of the ratio of magnetic shear s to safety factor q, which modifies the critical temperature gradient length for the onset of ion temperature gradients, and effects on the H-mode pedestal pressure.
Published: 2007

33. Characteristics of the H-mode pedestal in improved confinement scenarios in ASDEX Upgrade, DIII-D, JET and JT-60U

Author: C.F Maggi, R.J Groebner, N Oyama, R Sartori, L.D Horton, A.C.C Sips, W Suttrop, the ASDEX Upgrade Team, A Leonard, T.C Luce, M.R Wade, the DIII-D Team, Y Kamada, H Urano, the JT-60U Team, Y Andrew, C Giroud, E Joffrin, E. de la Luna, and EFDA-JET Contributors for the Pedes ITPA
Subjects: Nuclear and High Energy Physics, Jet (fluid), Tokamak, Materials science, DIII-D, Plasma parameters, Plasma, Condensed Matter Physics, Thermal conduction, law.invention, Pedestal, ASDEX Upgrade, law, Atomic physics
Abstract: Pedestal and global plasma parameters are compared in conventional ELMy H-modes and improved confinement discharges from ASDEX Upgrade (AUG), DIII-D, JET and JT-60U with varying net input power. Both electron and ion pedestal pressures are studied. The pedestal top pressure pPED increases moderately with power in all tokamaks, in broad agreement with the power dependence of the IPB98(y, 2) scaling. Higher pedestal pressures are observed in AUG improved H-modes and in JT-60U high βpol discharges at q95 ~ 6.5 and high triangularity. For all machines and all scenarios a robust correlation between the total and the pedestal thermal stored energy is observed, with the ratio of the two varying between ~0.3 and 0.5. However the relative importance of pedestal and core confinement varies from regime to regime. In AUG the confinement improvement with respect to the IPB98(y, 2) scaling is due to improved pedestal confinement in improved H-modes with early heating and to both improved pedestal and core confinement in improved H-modes with late heating. In DIII-D hybrid discharges the increase in confinement factor compared with conventional H-modes is due to improved confinement in the plasma core. JT-60U reversed shear H-modes have strong internal transport barriers and thus improved core performance. In all four tokamaks improved edge stability is correlated with increasing total βpol and H98(y,2) increases with pedestal βpol. The analysed multimachine data set supports a scaling expression for the pedestal stored energy derived under the assumption that the dominant loss term for the pedestal is by thermal conduction in the edge transport barrier region.
Published: 2007

34. Study of the β dependence of confinement and heat transport in ASDEX Upgrade

Author: L Vermare, F Ryter, C Angioni, A.G Peeters, J Stober, R Bilato, L.D Horton, B Kurzan, C.F Maggi, H Meister, J Schirmer, G Tardini, and the ASDEX Upgrade Team
Subjects: Nuclear and High Energy Physics, Jet (fluid), Materials science, ASDEX Upgrade, Heat transfer, Magnetic confinement fusion, Plasma, Atomic physics, Condensed Matter Physics, Thermal diffusivity, Scaling, Dimensionless quantity
Abstract: First β scan experiments have been made in ASDEX Upgrade in H-mode plasmas with type-I ELMs. Two sets of discharges, performed in different density ranges, scan β between βN = (1.4–2.2) and βN = (1.4–2). Global analysis of these dedicated experiments exhibits a strong unfavourable β scaling as Bτth ∝ β−0.9. This tendency is confirmed by a local analysis which shows an increase in the thermal heat diffusivity with increasing β as χeff/B ∝ β0.65. These results are discussed and compared with studies made in DIII-D, JET and JT-60U.
Published: 2007

35. Role ofTe/Tiand ∇vtorin ion heat transport of ASDEX Upgrade H-mode plasmas

Author: A Manini, C Angioni, A.G Peeters, F Ryter, A Jacchia, C.F Maggi, W Suttrop, and the ASDEX Upgrade Team
Subjects: Shearing (physics), Nuclear and High Energy Physics, Materials science, Cyclotron, Plasma, Electron, Condensed Matter Physics, Neutral beam injection, law.invention, Ion, ASDEX Upgrade, law, Atomic physics, Ion transporter
Abstract: Experiments in H-mode plasmas have shown that both heat and particle transport are sensitive to the ratio between electron and ion temperature (Te/Ti). While decreasing Te/Ti is beneficial for confinement, an increased electron heating in these so called 'hot ion plasmas' deteriorates the confinement. H-mode plasmas with low Te/Ti are often accompanied by high toroidal rotation velocity (v). Its gradient (∇v) can destabilize the ion temperature gradient mode (ITG) through its parallel component in the parallel velocity shear, but it has also stabilizing effects since it produces an E × B shearing rate (ωE × B). In this paper, the effects of electron heating on the ion heat transport is investigated in H-mode plasmas heated by neutral beam injection (NBI) and electron cyclotron heating (ECH). In particular, the correlation on Te/Ti and ∇v is studied and compared with calculations made with GLF23 and GS2. Experimentally it is shown that the normalized gradient length of the ions ( ) is correlated with both Te/Ti and ∇v: peaked ion temperature profiles are only obtained with low Te/Ti and high ∇v, and vice-versa. When ECH is added, both ion heat and momentum transport are enhanced, leading to a drop of both the Ti and v profiles. The effective growth rate γeff = γ−ωE × B is calculated, with the mode growth rate γ determined with GS2 and ωE × B with GLF23. The ion transport is enhanced due to the decrease of the ITG threshold with increasing Te/Ti. Comparison of the dependence of on Te/Ti and ∇v between experiments and modelling indicates that the deterioration of confinement cannot be explained by the changes in only Te/Ti or ∇v, but by the combined effects of both parameters. The changes in Te/Ti act directly on the ITG threshold, while the ones in ∇v modify the ωE × B shearing rate leading to changes in the effective threshold.
Published: 2006

36. Understanding of the density profile shape, electron heat transport and internal transport barriers observed in ASDEX Upgrade

Author: A.G Peeters, C Angioni, M Apostoliceanu, G.V Pereverzev, E Quigley, F Ryter, D Strintzi, F Jenko, U Fahrbach, C Fuchs, O Gehre, J Hobirk, B Kurzan, C.F Maggi, A Manini, P.J McCarthy, H Meister, J Schweinzer, J Stober, W Suttrop, G Tardini, and the ASDEX Upgrade Team
Subjects: Nuclear and High Energy Physics, Materials science, Condensed matter physics, Electron, Collisionality, Condensed Matter Physics, Molecular physics, Thermal conductivity, Heat flux, Physics::Plasma Physics, Electric field, Heat transfer, Electron temperature, Transport phenomena
Abstract: In this paper several transport phenomena are described and explained through a (quasi) linear description of the micro-instabilities. This paper deals with the following phenomena: density peaking, electron heat transport, density pump-out, reactor density profiles and the stabilization of the ion temperature gradient (ITG) mode in transport barriers. Density peaking is observed to increase with decreasing collisionality?a phenomenon that can be explained by the influence of collisions on the trapped electron response. The density pump-out due to central electron heating is observed to occur only if the dominant instability is the trapped electron mode (TEM). The proposed explanation involves the thermo-diffusive contribution to the particle flux which is outwards for the TEM while it is inwards for the ITG. The insight in the density profile behaviour can be used to predict moderately peaked density profiles in a reactor. Collisionality is also found to influence the electron heat flux in discharges with dominant electron heating even at relatively small values of the density. The dominant instability under dominant electron heating is found to be the TEM, and the dependence of the electron heat flux on the electron temperature gradient is reasonably described by the quasi-linear results. At higher density (and collisionality) the growth rate of the TEM is reduced and a transition to a dominant ITG is found. This transition is reflected in the speed of the electron heat pulse propagation. Finally, it has been found that the ITG under experimentally relevant conditions is not stabilized by a uniform radial electric field.
Published: 2005

37. The improved H-mode at ASDEX Upgrade: a candidate for an ITER hybrid scenario

Author: A Staebler, A.C.C Sips, M Brambilla, R Bilato, R Dux, O Gruber, J Hobirk, L.D Horton, C.F Maggi, A Manini, M Maraschek, A Mück, Y.-S Na, R Neu, G Tardini, M.R Wade, and ASDEX Upgrade Team
Subjects: Physics, Mode number, Nuclear physics, Nuclear and High Energy Physics, Toroid, Amplitude, ASDEX Upgrade, Gyroradius, Tearing, Magnetic confinement fusion, Plasma, Condensed Matter Physics
Abstract: A stationary regime with improved confinement (H98(y, 2) > 1) and, simultaneously, improved stability (βN > 2.5) compared to standard H-mode has been investigated on ASDEX Upgrade for many years. This so-called 'improved H-mode' is characterized by a q-profile with low central magnetic shear and q0 ≥ 1 that is obtained by early heating during the current ramp. Studies of this discharge scenario have been continued. New results are presented concerning the existence domain in the q95 range, the dependence on the normalized Larmor radius and initial experiments showing that high performance improved H-modes can be obtained with strong central ion cyclotron resonance heating (ICRH). In addition, the present status of understanding of the improved H-mode is reviewed. Improved H-mode plasmas are documented for 3.2 1 sawteeth as the main trigger of large amplitude neoclassical tearing modes are avoided. The stability is eventually limited by the occurrence of a mode with poloidal mode number m = 2 and toroidal mode number n = 1 at typically βN ~ 3. As far as the reactor relevance of this regime is concerned, its compatibility with significant central electron heating by ICRH, with high edge densities and low amplitude edge localized modes is of importance. The improved H-mode is, therefore, seen as a candidate for a long pulse ITER 'hybrid' operation.
Published: 2005

38. Tungsten: an option for divertor and main chamber plasma facing components in future fusion devices

Author: R Neu, R Dux, A Kallenbach, T Pütterich, M Balden, J.C Fuchs, A Herrmann, C.F Maggi, M O'Mullane, R Pugno, I Radivojevic, V Rohde, A.C.C Sips, W Suttrop, A Whiteford, and the ASDEX Upgrade team
Subjects: Nuclear and High Energy Physics, Materials science, Divertor, Magnetic confinement fusion, chemistry.chemical_element, Plasma, Tungsten, Condensed Matter Physics, chemistry, ASDEX Upgrade, Dielectric heating, Limiter, Plasma diagnostics, Atomic physics
Abstract: The tungsten programme in ASDEX Upgrade is pursued towards a full high-Z device. The spectroscopic diagnostic of W has been extended and refined and the cooling factor of W has been re-evaluated. The W coated surfaces now represent a fraction of 65% of all plasma facing components (24.8 m(2)). The only two major components that are not yet coated are the strikepoint region of the lower divertor as well as the limiters at the low field side. While extending the W surfaces, the W concentration and the discharge behaviour have changed gradually pointing to critical issues when operating with a W wall: anomalous transport in the plasma centre should not be too low, otherwise neoclassical accumulation can occur. One very successful remedy is the addition of central RF heating at the 20-30% level. Regimes with low ELM activity show increased impurity concentration over the whole plasma radius. These discharges can be cured by increasing the ELM frequency through pellet ELM pacemaking or by higher heating power. Moderate gas puffing also mitigates the impurity influx and penetration, however, at the expense of lower confinement. The erosion yield at the low field side guard limiter can be as high as 10(-3) and fast particle losses from NBI were identified to contribute a significant part to the W sputtering. Discharges run in the upper W coated divertor do not show higher W concentrations than comparable discharges in the lower C based divertor. According to impurity transport calculations no strong high-Z accumulation is expected for the ITER standard scenario as long as the anomalous transport is at least as high as the neoclassical one.
Published: 2005

39. Recent H-mode density limit studies at JET

Author: K Borrass, A Loarte, C.F Maggi, V Mertens, P Monier, R Monk, J Ongena, J Rapp, G Saibene, R Sartori, J Schweinzer, J Stober, W Suttrop, and EFDA-JET Workprogramme collaborators
Subjects: Physics, Nuclear and High Energy Physics, Jet (fluid), Safety factor, Extrapolation, Mode (statistics), Magnetic confinement fusion, Radius, Condensed Matter Physics, Computational physics, Nuclear physics, ASDEX Upgrade, ddc:530, Scaling
Abstract: Extensive studies of the H-mode density limit (DL) in JET gas-puffed discharges have been performed in the past four years targeting at an improved database for extrapolation to ITER. This paper reviews the arguments for the particular DL definition (pedestal density at the H-L boundary), the logic underlying the choice of parameters under focus (toroidal field, major radius, triangularity, safety factor) as well as some improvement in the interpretation of typical JET density ramp-up signatures that led to a critical review of the existing data. An empirical scaling is derived and compared with existing empirical and model based scalings. ASDEX Upgrade data are included in this analysis to provide information on the size dependence. The main results are: earlier findings on the B-t, R and q(95)-dependences are confirmed. The triangularity dependence, if any, is weak. The SOL-based BLS (Borrass, Lingertat, Schneider) scaling and the empirical scaling are virtually indistinguishable. The Greenwald scaling provides values in the right absolute range, but the overall fit is comparatively poor. The proposed scaling predicts ITER critical densities considerably below the reference value. Fuelling methods other than gas-puffing are outside the scope of this paper, but pellet fuelling, envisaged for ITER as an option to alleviate the situation, is discussed.
Published: 2004

40. EFD-C(13)03/12 M-mode: Axi-Symmetric Magnetic Oscillation and ELM-less H-mode in JET

Author: E.R. Solano, N. Vianello, P. Buratti, B. Alper, R. Coelho, E. Delabie, S. Devaux, D. Dodt, A. Figueiredo, L. Frassinetti, D. Howell, E. Lerche, C.F. Maggi, A. Manzanares, A. Martin, J. Morris, S. Marsen, K. McCormick, I. Nunes, D. Refy, F. Rimini, A. Sirinelli, B. Sieglin, S. Zoletnik, and JETEFDA contributors
Subjects: Physics::Plasma Physics
Abstract: Recent experimental studies of H-mode plasmas in JET have revealed an n = 0 m = 1 magnetic oscillation starting immediately at the L to H transition (called M-mode for brevity). While the oscillation is present a weak ELM-less H-mode regime is obtained (medium confinement), with a clear increase of pedestal density (ne,ped) and a weak temperature pedestal (Te,ped). In ICRH heated plasmas or low power, low density NBI plasmas the mode and the pedestal pressure can remain steady for the duration of the heating phase, of order 10s or more. The observed axisymmetric MHD oscillation has period ~12ms, and odd parity across the mid-plane: m = 1 with sin(q) dependency. Electron Cyclotron Emission, interferometry, reflectometry, SXR and fast Li beam measurements locate the mode in the pedestal region. Da, fast infrared camera and Langmuir probe measurements show that the mode modulates heat and particle flux to the target. Similar phenomena are described elsewhere, lately described as an "I-phase". From a physics point of view, our fundamental observation is that the M-mode is magnetic, not electrostatic, and its frequency scales with pedestal poloidal Alfvén velocity.
Published: 2013
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41. EFD-C(13)03/07 L to H Mode Transition: On the Role of Zeff

Author: C. Bourdelle, C.F. Maggi, L. Chôné, P. Beyer, G. Fuhr, X. Garbet, A. Loarte, F. Millitello, A. Monnier, M. Romanelli, S. Saarelma, Y. Sarazin, and JET EFDA contributors
Abstract: In this paper, the nature of the primary instability present in the pedestal forming region prior to the transition into H mode will be analyzed by a gyrokinetic code GENE on JET ITER Like Wall (ILW) profiles. It will be shown that the primary instability is of resistive nature, and can therefore be stabilized by increased temperature, hence power. Its growth rate reaches a minimum for a temperature of the order of the experimentally measured temperature at the transition. Its resistive nature leads to a reduced growth rate as the effective charge Zeff is increased. This dependence will be shown to be in qualitative agreement with recent experimental observations. The impact of the ILW shows a L to H mode power threshold reduced by ~ 40% in ILW with respect to similar experiments in C wall. The experiments were carried out with slow power ramps and matched plasma shapes, divertor configurations and Ip/BT pairs. In ASDEX Upgrade as well, a reduction of the power threshold, linked to the metalization of the machine, has been observed when compared to the ITPA-2008 scaling law. A common feature of JET ILWand ASDEX Upgrade is an observed significant reduction of the Zeff when switching from C walls to metallic ones.
Published: 2013
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42. EFD-P(13)17 Scenario Development at JET with the New ITER-like Wall

Author: E. Joffrin, M. Baruzzo, M. Beurskens, Bourdelle, S. Brezinsek, J. Bucalossi, P. Buratti, G. Calabro, C.D. Challis, M. Clever, J. Coenen, E. Delabie, R. Dux, P. Lomas, E. de la Luna, P. de Vries, J. Flanagan, L. Frassinetti, D. Frigione, C. Giroud, M. Groth, N. Hawkes, J. Hobirk, M. Lehnen, G. Maddison, J. Mailloux, C.F. Maggi, G. Matthews, M. Mayoral, A. Meigs, R. Neu, I. Nunes, T. Puetterich, F. Rimini, M. Sertoli, B. Sieglin, A.C.C. Sips, G. van Rooij, I. Voitsekhovitch, and JET EFDA contributors
Abstract: E. Joffrin, M. Baruzzo, M. Beurskens, Bourdelle, S. Brezinsek, J. Bucalossi, P. Buratti, G. Calabro, C.D. Challis, M. Clever, J. Coenen, E. Delabie, R. Dux, P. Lomas, E. de la Luna, P. de Vries, J. Flanagan, L. Frassinetti, D. Frigione, C. Giroud, M. Groth, N. Hawkes, J. Hobirk, M. Lehnen, G. Maddison, J. Mailloux, C.F. Maggi, G. Matthews, M. Mayoral, A. Meigs, R. Neu, I. Nunes, T. Puetterich, F. Rimini, M. Sertoli, B. Sieglin, A.C.C. Sips, G. van Rooij, I. Voitsekhovitch and JET EFDA contributors In the recent JET experimental campaigns with the new ITER-like Wall (JET-ILW), major progress has been achieved in the characterisation and operation of the H-mode regime in metallic environment: i) plasma breakdown has been achieved at the first attempt and X-point L-mode operation recovered in a few days of operation, ii) stationary and stable type I ELMy Hmodes with bN~1.4 have been achieved in low and high triangularity ITERlike shape plasmas and are showing that their operational domain at H = 1 is significantly reduced with the JET-ILW mainly because of the need to inject large amount of gas (above 1022D/s) to control core radiation. iii) in contrast the hybrid H-mode scenario has reached H factor of 1.2 to 1.3 at bN of 3 for 2 to 3s. iv) in comparison to carbon equivalent discharges, total radiation is similar but the edge radiation is lower and Zeff of the order of 1.3-1.4. At low gas fuelling rate (below 0.5 1022D/s) and low ELM frequency (typically less than 10Hz), strong core radiation peaking is observed in H-mode discharges even when tungsten influx from the divertor is constant. High Z impurity transport from the plasma edge to the core appears to be the dominant factor to explain is paper reviews the major physics and operational achievements and challenges that an ITERlike wall configuration has to face to produce stable plasma scenarios with maximised performance.
Published: 2013
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43. EFD-P(13)26 L-H Power Threshold Studies in JET with Be/W and C Wall

Author: C.F. Maggi, E. Delabie, T.M. Biewer, M. Groth, N.C. Hawkes, M. Lehnen, E. de la Luna, K. McCormick, C. Reux, F. Rimini, E.R. Solano, Y. Andrew, C. Bourdelle, V. Bobkov, M. Brix, G. Calabro, A. Czarnecka, J. Flanagan, E. Lerche, S. Marsen, I. Nunes, D. Van Eester, M.F. Stamp, and JET EFDA contributors
Abstract: C.F. Maggi, E. Delabie, T.M. Biewer, M. Groth, N.C. Hawkes, M. Lehnen, E. de la Luna, K. McCormick, C. Reux, F. Rimini, E.R. Solano, Y. Andrew, C. Bourdelle, V. Bobkov, M. Brix, G. Calabro, A. Czarnecka, J. Flanagan, E. Lerche, S. Marsen, I. Nunes, D. Van Eester, M.F. Stamp and JET EFDA contributors A comparison of the L-H power threshold (Pthr) in JET with all carbon, JET-C, and beryllium/tungsten wall (the ITER-like choice), JET-ILW, has been carried out in experiments with slow input power ramps and matched plasma shapes, divertor configuration and IP/BT pairs. The low density dependence of the L-H power threshold, namely an increase below a minimum density ne,min, which was first observed in JET with the MkII-GB divertor and C wall and subsequently not observed with the current MkII-HD geometry, is observed again with JET-ILW. At plasma densities above ne,min, Pthr is reduced by ~ 30%, and by ~ 40% when the radiation from the bulk plasma is subtracted (Psep), with JET-ILW compared to JET-C. At the L-H transition the electron temperature at the edge, where the pedestal later develops, is also lower with JET-ILW, for a given edge density. With JET-ILW the minimum density is found to increase roughly linearly with magnetic field, ne,min ~ BT4/5, while the power threshold at the minimum density scales as Psep,min ~ BT5/2. The H-mode power threshold in JET-ILW is found to be sensitive both to variations in main plasma shape (Psep decreases with increasing lower triangularity and increases with upper triangularity) and in divertor configuration. When the data are recast in terms of Psep and Zeff or subdivertor neutral pressure a linear correlation is found, pointing to a possible role of Zeff and/or subdivertor neutral pressure in the L-H transition physics. Depending on the chosen divertor configuration, Pthr can be up to a factor of two lower than the ITPA scaling law for densities above ne,min. A shallow edge radial electric field well is observed at the L-H transition. The edge impurity ion poloidal velocity remains low, close to its L-mode values, 5 km/s ±23km/s, at the L-H transition and throughout the H-mode phase, with no measureable increase within the experimental uncertainties. The edge toroidal rotation profile does not contribute to the depth of the negative Er well and thus may not be correlated with the formation of the edge transport barrier in JET.
Published: 2013
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44. EFD-C(13)03/14 Dynamic of Density Profiles in JET During Slow L-H Transition

Author: R. Sabot, Ph. Ghendrih, A. Sirinelli, P. Tamain, C. Bourdelle, M. Brix, G. Calabro, E. Delabie, G. Dif-Pradalier, N. Fedorzack, X. Garbet, N. Hawkes, C.F. Maggi, F. Rimini, E.R. Solano, and JET-EFDA contributors
Subjects: Physics::Plasma Physics
Abstract: In tokamaks, the H-mode is characterized by density and temperature pedestals that build up at the L-H transition. During JET 2012 campaign, discharges were carried out with a smooth increase of heating power to compare the L-H transition threshold in JET-C and JET-ILW. In these discharges, plasma passed through intermediate regimes between the L-mode and the H-mode: divertor oscillation and M-mode. The divertor oscillation (DO) is characterized by a periodic (typ. 10ms) oscillation of plasma radiation with an opposition of phase between the inner and outer side Da signal. Although reminiscent of the dithering L-H transitions, several features distinguish the divertor oscillations. The DO is an oscillation between two different plasma states: firstly the edge plasma density increases with low divertor radiation, secondly follows a sudden decrease of the plasma density with increased divertor radiation. During the high plasma density phase, the plasma stored energy increases slightly whereas dithering cycles are periodic L-H-L transitions at frequency an order of magnitude higher. Improvement of reflectometry data processing to reduce noise and radial jitter allows to follow the dynamic of the density profile during the DO. This study is preliminary; a very limited number of shots were processed. The observations lead us to propose a simple model to explain the periodic density oscillations.
Published: 2013
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45. EFD-P(13)60 ITER-Like Current Ramps in JET with ILW: Experiments, Modelling and Consequences for ITER

Author: G.M.D. Hogeweij, G. Calabrò, A.C.C. Sips, C.F. Maggi, G.M. De Tommasi, E. Joffrin, A. Loarte, F. Maviglia, J. Mlynar, F.G. Rimini, Th. Pütterich, and JET EFDA contributors
Abstract: Since the ITER-like wall in JET (JET-ILW) came into operation, dedicated ITER-like plasma current (Ip) ramp-up (RU) and ramp-down (RD) experiments have been performed and matched to similar discharges with the carbon wall (JET-C). The experiments show that access to H-mode early in the Ip RU phase and maintaining H-mode in the Ip RD as long as possible are instrumental to achieve low internal plasma inductance (li) and to minimize flux consumption. The measured H-mode power threshold during Ip RU is similar to that obtained during flat top, and lower than in JET-C. In JET-ILW, at a given current rise rate similar variations in li (0.70.9) are obtained as in JET-C. In most discharges no strong W accumulation is observed. However, in some low density cases during the early phase of the Ip RU (ne/neGw ~ 0.2) strong core radiation due to W influx led to hollow electron temperature (Te) profiles. In JET-ILW Zeff is significantly lower than in JET C. W significantly disturbs the discharge evolution when the W concentration approaches 104; this threshold is confirmed by predictive transport modelling using the CRONOS code. Similar modelling for the ITER Ip RU showed a comparable critical W concentration, however with opposite effect: in ITER a too high Wconcentration leads to a very peaked Te profile and too high li. Ip RD experiments in JET-ILW confirm the result of JET-C that sustained H-mode and elongation reduction are both instrumental in controlling li.
Published: 2013
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46. EFD-P(13)55 Tungsten Transport in JET H-mode Plasmas in Hybrid Scenario, Experimental Observations and Modelling

Author: C. Angioni, P. Mantica, T. Pütterich, M. Valisa, M. Baruzzo, E.A. Belli, P. Belo, F.J. Casson, C. Challis, P. Drewelow, C. Giroud, N. Hawkes, T.C. Hender, J. Hobirk, T. Koskela, L. Lauro Taroni, C.F. Maggi, J. Mlynar, T. Odstrcil, M.L. Reinke, M. Romanelli, and JET EFDA contributors
Abstract: The behaviour of tungsten in the core of hybrid scenario plasmas in JET with the ITER-like wall is analyzed and modelled with a combination of neoclassical and gyrokinetic codes. In these discharges, good confinement conditions can be maintained only for the first 2 - 3 seconds of the high power phase. Later W accumulation is regularly observed, often accompanied by the onset of magnetohydrodynamical activity, in particular neoclassical tearing modes (NTMs), both of which have detrimental effects on the global energy confinement. The dynamics of the accumulation process is examined, taking into consideration the concurrent evolution of the background plasma profiles, and the possible onset of NTMs. Two time slices of a representative discharge, before and during the accumulation process, are analysed with two indipendent methods, in order to reconstruct the W density distribution over the poloidal cross-section. The same time slices are modelled, computing both neoclassical and turbulent transport components and consistently including the impact of centrifugal effects, which can be significant in these plasmas, and strongly enhanceW neoclassical transport. The modelling closely reproduces the observations and identifies inward neoclassical convection due to the density peaking of the bulk plasma in the central region as the main cause of the accumulation. The analysis of a large set of discharges provides clear indications that this effect is generic in this scenario. The unfavorable impact of the onset of NTMs on the W behaviour, observed in several discharges, is suggested to be a consequence of a detrimental combination of the effects of neoclassical transport and of the appearance of an island.
Published: 2013
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47. EFD-P(13)34 L to H Mode Transition: On the Role of Zeff

Author: C. Bourdelle, C.F. Maggi, L. Chôné, P. Beyer, J. Citrin, N. Fedorczak, X. Garbet, A. Loarte, F. Millitello, M. Romanelli, Y. Sarazin, and JET EFDA contributors
Abstract: In this paper, the nature of the primary instability present in the pedestal forming region prior to the transition into H mode is analyzed using a gyrokinetic code on JET-ILW profiles. The linear analysis shows that the primary instability is of resistive nature, and can therefore be stabilized by increased temperature, hence power. Its growth rate reaches a minimum for a temperature corresponding to the magnitude of the experimentally measured temperature at the L-H transition. The minimum of the growth rate is shifted towards lower temperature for lower effective charge Zeff. This dependence is shown to be in qualitative agreement with recent and past experimental observations of reduced Zeff associated with lower L-H power thresholds.
Published: 2013
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48. EFD-C(13)03/39 Study of Physical and Chemical Sputtering of Beryllium in the JET ITER-LikeWall

Author: S. Brezinsek, M.F. Stamp, D. Nishijima, D. Borodin, G. Arnoux, M. Clever, S. Devaux, K. Krieger, C.F. Maggi, S. Marsen, A.G. Meigs, M. O'Mullane, and JET EFDA contributors
Abstract: JET is equipped with a first wall material combination comparable to the ITER selection acomprising beryllium (Be) in the main chamber and tungsten (W) in the divertor and some recessed wall areas. Be is selected owing to its low atomic number, its low tritium retention and excellent getter properties, but material erosion limits the lifetime of plasma-facing components PFCs made of Be. Initial ERO modelling of the shaped Be first wall modules close to the ITER separatrix predict high erosion rates and limited armour lifetime. However, uncertainties in the modelling, in particular in the atomic data and sputtering yields, still exist and further bench- mark under ITER-comparable tokamak conditions is required. The ITER-Like Wall in JET (JET-ILW) demonstrated successful plasma operation, strong reduction of the C content (x20), and high plasma purity (Zeff ~ 1.2). Equipped with its bulk Be limiters, the JET-ILW allows the study of Be erosion by optical emission spectroscopy and observation of various transitions of BeI (e.g. 457nm), BeII (e.g. 527nm) and the BeD A-X band under different plasma conditions and surface temperatures. The total Be sputtering consists of the bare physical sputtering and the chemical assisted physical sputtering sometimes referred as swift chemical sputtering. However, the composition of the total sputtering, its dependence on the impact energy and temperature, the strength of the chemical assisted physical sputtering are not known for a high temperature plasma edge conditions as present in the JET-ILW or in future ITER. Here, deuterium plasmas in limiter configuration have been used to vary the local electron temperature (Te) in the scrape-off layer (SOL), or better, scanning the impact energy of the impinging deuterons (Ei), as well as, to vary the PFC surface temperature (Tsurf) by plasma impact as they are only inertially cooled. The increase of Tsurf is expected to inhibit the sputtering channel via BeD which thermally decomposes at about 540K according to studies in PISCES.
Published: 2013
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49. EFD-C(13)03/20 Experimental Study of H-L Transitions in JET

Author: C.F. Maggi, E. Delabie, N. Hawkes, M. Lehnen, G. Calabro, F. Rimini, E.R. Solano, and JET EFDA contributors
Abstract: ITER operation scenarios foresee the access to H-mode with limited additional heating at low density, followed by an increase in density and power while remaining in H-mode to the required operating conditions. Such scheme is thus sensitive to the level of hysteresis in the H-mode power and to the competing evolution of input power, density and radiation losses from the bulk plasma. Whereas most studies focus on the access to H-mode, the H-L back transition is less explored. This work examines the evolution and properties of JET plasmas with the ITER-like wall at the H-L back transition in relation to the forward L-H transition. The influence of the wall composition (C versus Be/W), in particular on the density evolution, radiation losses and impurity composition, is also analysed, through direct comparison of forward and back transitions in JET-C and JET-ILW plasmas.
Published: 2013
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50. EFD-C(13)03/46 Comparisons Between EDGE2D/EIRENE Simulations and D and Low Z Impurity Spectral Emission from JET ITER-like Wall L-mode Plasmas

Author: K.D. Lawson, M. Groth, C.F. Maggi, R. Barnsley, P. Belo, S. Brezinsek, G. Corrigan, D. Harting, M. Lehnen, S. Marsen, A.G. Meigs, M.F. Stamp, S. Tyrrell, and JET EFDA contributors
Subjects: Physics::Plasma Physics
Abstract: An understanding of the behaviour of the plasma edge and divertor physics is essential for the design of next-step machines such as ITER, for which JET with its ITER-Like Wall (ILW) of Be in the main chamber and W in the divertor is ideally suited. The fuel and edge impurities affect the power balance, this determining the power reaching the divertor target plates, which are limited by the mechanical and thermal properties of the plates. A recent comparison of L-mode discharges run during the present JET-ILW campaign and previous JET-C campaigns, in which the plasma-facing surfaces were predominately C, have consistently shown a shortfall in the radiated power calculated from EDGE2D/EIRENE simulations below that measured by bolometry. In order to understand this discrepancy, the contributions to the divertor radiated power as predicted by the simulations have been quantified and the results compared with measurements from a recently upgraded poloidally scanning VUV/visible spectrometer.
Published: 2013
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