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Start Over Author "J. P. Coad" Journal plasma physics and controlled fusion
4 results on '"J. P. Coad"'

1. Material erosion and migration in tokamaks

Author

G. Federici, J. Strachan, R.A. Pitts, Marek Rubel, Jari Likonen, D. P. Coster, G. F. Matthews, Jet-Efda Contributors, K. Krieger, Wojciech Fundamenski, A. Kukushkin, J. P. Coad, and J. Horacek

Subjects
Tokamak, Nuclear engineering, fusion reactors, Context (language use), law.invention, Nuclear physics, law, ITER, divertor, divertor tiles, tokamak, plasma, Divertor, Magnetic confinement fusion, Plasma, Fusion power, first wall, Condensed Matter Physics, fusion energy, Nuclear Energy and Engineering, JET, Duty cycle, Environmental science, Transient (oscillation), divertor material, plasma-wall interactions
Abstract

The issue of first wall and divertor target lifetime represents one of the greatest challenges facing the successful demonstration of integrated tokamak burning plasma operation, even in the case of the planned next step device, ITER, which will run at a relatively low duty cycle in comparison to future fusion power plants. Material erosion by continuous or transient plasma ion and neutral impact, the susbsequent transport of the released impurities through and by the plasma and their deposition and/or eventual re-erosion constitute the process of migration. Its importance is now recognized by a concerted research effort throughout the international tokamak community, comprising a wide variety of devices with differing plasma configurations, sizes and plasma-facing component material. No single device, however, operates with the first wall material mix currently envisaged for ITER, and all are far from the ITER energy throughput and divertor particle fluxes and fluences. This paper aims to review the basic components of material erosion and migration in tokamaks, illustrating each by way of examples from current research and attempting to place them in the context of the next step device. Plans for testing an ITER-like first wall material mix on the JET tokamak will also be briefly outlined.

Published
2005
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2. Hydrocarbon transport in the MkIIa divertor of JET

Author

A Kirschner, J N Brooks, V Philipps, J P Coad, and contributors to the EFDA-JET Workprogramme

Subjects
chemistry.chemical_classification, Jet (fluid), Materials science, Divertor, chemistry.chemical_element, Magnetic confinement fusion, Mechanics, Plasma, Condensed Matter Physics, Hydrocarbon, Nuclear Energy and Engineering, chemistry, Ionization, Erosion, ddc:530, Atomic physics, Carbon
Abstract

This contribution presents two-dimensional Monte-Carlo simulations of the local transport of hydrocarbons that are chemically eroded in the JET MkIIa divertor. The effect of a given background carbon flux flowing from the main plasma down to the divertor is also taken into account. The influence of local plasma temperatures and densities and the influence of different assumptions for the sticking of re-deposited particles hitting the tiles is analysed. Even under the assumption that the sticking of re-deposited hydrocarbon fragments is zero, a large amount (about 75%) of the eroded particles is re-deposited in the form of ionized carbon on the tiles. A reasonable agreement between the simulation and the experimental observation of the carbon deposition at the inner louvers in the MkIIa JET divertor is achieved, if high chemical erosion yields of about 20% together with a negligible effective sticking of hydrocarbons are assumed. Although there are experimental observations indicating such high erosion yields, such yields cannot be applied as a stationary value for the effective erosion since it would turn the inner divertor into a net erosion area in contrast to the experimental findings. The possibility of applying different erosion rates for (re)-deposited layers and the substrate material is discussed. To further improve the modelling a better knowledge about the formation and erosion of re-deposited layers is required. A first conclusion concerning the erosion and re-deposition behaviour in ITER will be drawn.

Published
2003
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3. Overview of high performance H-modes in JET

Author

A. C. C. Sips, A.E. Costley, F. Hurd, G. Saibene, M. Salisbury, M. Brusati, C. Perry, P. J. Harbour, T. Martin, J. P. Poffe, Laurie Porte, H. van der Beken, N. C. Hawkes, J. Wesson, M. Bures, G. Janeschitz, M. Huart, A. Santagiustina, G. Bosia, H. Altmann, J. L. Salanave, A. Dines, N. G. Kidd, F. Junique, E. Righi, P. J. Lomas, P. G. Doyle, J. G. Cordey, G. Magyar, V. V. Parail, K. Thomsen, A. Gondhalekar, M. Irving, C. Gowers, R. Ostrom, C. Woodward, A. Galetsas, A. Loarte, P. Card, P. Trevalion, A. M. Edwards, T. P. Hughes, F. Jensen, M. Newman, C. Caldwell-Nichols, N. Peacock, P. Smeulders, A. Korotkov, A. Colton, P. Chuilon, T. T. C. Jones, F.G. Rimini, T. Winkel, P. Stubberfield, M. A. Pick, J.A. Hoekzema, T. Szabo, J. M. Adams, R. Prentice, Wolfgang Kerner, L. Zannelli, M. Rapisarda, D.F.H. Start, L. G. Eriksson, P. Schild, M. Wykes, D. Wilson, S. J. Davies, A. Sibley, P. Haynes, B. Alper, R. Wolf, T. Elevant, R. T. Ross, J. O'Rourke, E. Thompson, C. J. Hancock, R. Haange, P. E. Stott, A. Tesini, B. Macklin, M. Baronian, W. J. Brewerton, M.F. Stamp, L. P. D. F. Jones, A. C. Maas, B. E. Keen, A. Taroni, H. Morsi, G. Murphy, H. D. Falter, M. Keilhacker, I. D. Young, M. von Hellermann, A. Girard, A. Haigh, M. Cooke, A. Cherubini, Henrik Bindslev, D. Goodall, L. Horton, S. K. Erents, J.A. Dobbing, M. Gadeberg, E. Deksnis, G. Matthews, M. Comiskey, T. Wade, F. Marcus, M. Schmid, P. Burton, M. Garribba, G. Newbert, P. Barabaschi, A. Peacock, V. Marchese, C. Froger, K. D. Lawson, P. Noll, M. Brandon, G. Sadler, P. R. Thomas, C. F. Maggi, W. Bailey, D. Ward, K. Blackler, A. Rolfe, T. J. Wijnands, R. Barnsley, G. Celentano, R. Russ, Annika Ekedahl, G. Vayakis, T. Bonicelli, P. Froissard, C. Walker, J. Jacquinot, J. Plancoulaine, P. Kupschus, N. Dolgetta, Y. Agarici, D. Summers, M. Ottaviani, H. Brelen, S. Ali-Arshad, C. Sborchia, R. Claesen, C. A. Steed, S. F. Mills, A. Gibson, R. Smith, B. Schunke, B.J.D. Tubbing, J. Mart, H. McBryan, L. Svensson, J. J. Davis, S. M. Scott, R. J. M. Pearce, J. P. Coad, F. Soldner, T. Budd, P. Stangeby, E. M. Jones, V.P. Bhatnagar, C. D. Challis, R. Rookes, D. Campling, I. Coffey, W. Zwingmann, A. C. Bell, E. Oord, D. O'Brien, P. Gaze, N. Davies, D. Bond, David Campbell, P. Barker, F. Nave, G. B. Denne-Hinnov, S. Papastergiou, R. Monk, S. L. Dmitrenko, B. Balet, P. Butcher, L. Rossi, K. Borras, O. Da Costa, R. Giannella, P. Massmann, R. D. Gill, R. Sartori, J. Lingertat, S. Weber, R. N. Litunovski, H. Buttgereit, J. Ehrenberg, B. Patel, R. Lasser, N. A. Gottardi, A. Kaye, T. Brown, J. Christiansen, T. Businaro, L. Lauro-Taroni, C. Gormezano, O. N. Jarvis, S. Clement, A. J. Bickley, J. Freiling, D.V. Bartlett, D. Chiron, M. Botman, B. Ingram, C. Terella, C. Lowry, W. Obert, M. Tabellini, S. Corti, S. Cooper, P. Bertoldi, E. Bertolini, H. Summers, P.D. Morgan, P. Crawley, R. Reichle, Francesco Porcelli, G. Sanazzaro, G. Corrigan, T. Raimondi, G. Deschamps, M. J. Watson, M. C. Ramos de Andrade, G. Fishpool, H. Deesch, J. L. Hemmerich, G. Benali, Y. Baranov, H. Jaeckel, S. E. Dorling, G. Radford, S. J. Booth, J. F. Junger, H. Duquenoy, M. Lennholm, L. Galbiati, W. J. Dickson, N. P. Hawkes, R. Simonini, Michael Loughlin, T. Hender, M. Cox, P. Breger, W. Suverkropp, M. Nilsen, M. L. Watkins, S. Puppin, D. Stork, S. Richards, P. Nielsen, P. Boucquey, G.A. Cottrell, A. Tanga, P. J. Howarth, K. Fullard, D. Martin, M. Johnson, J. F. Jaeger, P. Andrew, P. Meriguet, Ralf König, M. O'Mullane, N. Deliyanakis, E. Martin, G. Vlases, and J. How

Subjects
Physics, Nuclear Energy and Engineering, Diamagnetism, Plasma, Atomic physics, Condensed Matter Physics, Phenomenology (particle physics), Scaling, Ion
Abstract

An account is given of the high performance plasmas established by development of the H-mode regime in JET in the experimental campaigns up to 1992. High performance in this case is measured in terms of the confinement enhancement achieved over the L-mode scaling as measured using the plasma diamagnetism. Three JET H-mode regimes have achieved enhancement factors (H G DIA ) over Goldston L-mode scaling of 2.5 < H G DIA < 4.0. These are the Pellet Enhanced Performance (PEP) H-MODE, the high bootstrap fraction (high β POL ) H-mode and the Hot Ion (HI) H-mode. The phenomenology of these three regimes is reviewed and contrasts and common threads are elucidated

Published
1994
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4. Plasma heating in JET

Author

A Ainsworth, H Altmann, R J Anderson, J Arbez, D Bartlett, W Bailey, K Behringer, E Bertolini, P Bertoldi, C H Best, V Bhatnagar, R J Bickerton, G Boissin, T Bonicelli, S Booth, A Boschi, G Bosia, M Botman, H Brelen, H Brinkschulte, M L Browne, M Brusati, T Budd, M Bures, P Butcher, H Buttgereit, D Cacaut, C Caldwell-Nichols, D Campbell, J Carwardine, G Celentano, C D Challis, A Cheetman, J Christiansen, C Christodoulopoulos, P Chuilon, R Claesen, J P Coad, M Cooke, J G Cordey, W Core, S Corti, A E Costley, G Cottrell, J Dean, E Deksnis, G Deschamps, K J Dietz, J Dobbing, S E Dorling, D F Duechs, G Duesing, H Duquenoy, L de Kock, A Edwards, W Engelhardt, F Erhorn, B Eriksson, H Falter, T Hellsten, J L Hemmerich, R Hemsworth, F Hendriks, R F Herzog, L Horton, J How, M Huart, A Hubbard, M Hugon, P Jones, J Kaeline, A Kaellne, A Kaye, B E Keen, M Keilhacker, G Kinahan, A Konstantellos, P Kupschus, P Lallia, J R Last, N Foden, C Froger, K Fullard, A Galetsas, A Gallacher, A Gibson, R D Gill, A Geode, A Gondhalekar, N A Gottardi, C Gowers, R Granetz, B Green, S Gregoli, F S Griph, R Haange, C J Hancock, P Harbour, R F Herog, J Kaellne, L Lauro-Taroni, E Lazzaro, R C Lobel, P Lomas, M Lorenzo-Gottardi, C Lowry, G Magyar, D Maissonneir, M Malacarne, V Marchese, P Massmann, P McMullen, M J Mead, P Meriguet, V Merlo, S Mills, P Millward, A Moissonnier, P L Mondini, P Morgan, G Murphy, M F Nave, L Nickesson, P Nielson, P Noll, S Nowak, W Obert, B Oliver, M Olsson, J O'Rourke, M G Pacco, J Paillere, L Pannacione, S Papastergiou, D Pasini, M Pescatore, J Planncoulaine, J P Poffe, R Prentice, T Raimondi, C Raymond, P H Rebut, J Removille, W Riediker, R Roberts, A Rolfe, R T Ross, G Sadler, J Saffert, N Salmon, A Sand, A Santagiustina, R Saunders, M Schmid, F C Schueller, K Selin, R Shaw, D Sigournay, R Simonini, P Smeulders, L Sonnerup, K Sonnenberg, M Stamp, C A Steed, D Stork, P E Stott, T E Stringer, D Summers, A Tanga, A Taroni, A Terrington, A Tesini, P R Thomas, E Thompson, F Tibone, R Tivery, E Usselmann, H Van der Beken, M Von Hellerman, J E Van Montfoort, T Wade, C Walker, B A Wallander, M Walravens, K Walter, M L Watkins, M Watson, D Webberley, J Wesson, J Wilks, T Winkel, C Woodward, M Wykes, D Young, L Zennelili, J Zwart, B Beaumont, D Gambier, D Moreau, J Ehrenberg, H Jaeckel, S Kissel, U Kuephnapfel, R Mueller, A Staebler, A Weller, J H Hamnen, M Evrared, M Gadeberg, K Thomsen, P Dupperrex, G Tonetti, N Lopez-Cardozo, B Tubbing, J Von Seggern, J Tagle, F Bombarda, G Bracco, R Giannella, R Carolan, M Cox, M Forrest, D Goodall, N Hawkes, P Haynes, J Hugill, K D Lawson, G McCracken, J Partridge, N Peacock, J Snipes, T Todd, H Schamel, H Summers, and S Tsuji

Subjects
Jet (fluid), Settore FIS/03, Materials science, Nuclear Energy and Engineering, Resonance, Electron temperature, Plasma, Sawtooth wave, Electron, Atomic physics, Condensed Matter Physics, Neutral beam injection, Ion
Abstract

Heating the JET plasma well above temperatures reached in the ohmic phase is the aim of the two additional heating systems planned for JET: ion cyclotron resonance heating (ICRF) and neutral beam injection (NBI). Operations with the latter started in February 1986, initially with hydrogen injection, up to a power level of 7 MW. ICRF power has been delivered to the plasma by three antennae and has reached power levels of 6 MW for 2 s. In most experiments, the frequency of the waves is adjusted to position the minority ion resonance layer close to the centre of the discharge, resulting in a centrally peaked power deposition profile. Results have also shown that the increase of the volume averaged electron temperature was much less dependent on the radial position of the ion resonance layer than were the central temperatures of both ions and electrons which can both approach 5 keV. In cases of 'on axis' heating, large increases in the sawtooth activity is observed with sawtooth periods exceeding 0.3 s. Initial results with NBI have shown a decrease of the global energy confinement time with additional power similar to the one observed with ICRF heating.

Published
1986
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