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The high voltage Padova test facility (HVPTF) is an experimental device for the study of HV insulation in vacuum, in support of the realization of the prototype of a neutral beam injector for International Thermonuclear Experimental Reactor (ITER), named megavolt ITER injector and concept advancement (MITICA). The facility investigates the physical phenomena underlying voltage holding in vacuum, in particular the mechanisms causing breakdowns and the electrode conditioning process. At HVPTF, inside a high vacuum chamber, two stainless steel electrodes, separated by a few centimeters gap, can achieve HV values for a maximum potential difference of 800 kV. During the voltage conditioning of the electrodes, current MicroDischarges (MDs) and high-energy X-rays are observed and analyzed. In this work, we present a characterization of the MD dynamics occurring during the conditioning process, with the aim to gain information on the reason of the growing difference between the current contributions measured by the two electrodes. The analysis will be performed due to two new X-rays detectors recently installed: an lutetium yttrium orthosilicate (LYSO) and a LaBr3(Ce) scintillating crystal. The new diagnostics indeed provide the fine dynamics of a single MD, recording energy and time of each single detected X-ray. In particular, we compare the MD dynamics at the beginning and at the end of the conditioning process and try to give a preliminary interpretation of the observations.

The results are presented of an experimental activity performed in the RFX-mod device aimed at characterizing plasma dynamics in the so-called Ultralow-q (ULq) magnetic configuration, which corresponds to edge safety factor values below 1. The role of the edge safety factor in determining plasma dynamics is studied. In particular, a characterization of MHD activity is performed. The results of dedicated non-linear 3D visco-resistive MHD simulations are in good quantitative agreement with the experimental observations. In particular, the predicted tendency for ULq plasmas to be characterized by magnetic spectra dominated by a single mode (either a kink or a double resonant internal mode) is confirmed by experiment. Magnetic reconnection plays a relevant role in determining the dynamics of the magnetic topology. Both almost quiescent and largely fluctuating plasmas are observed with a strong sensitivity on the edge safety factor. The main MHD properties of the ULq are compared to those of RFP and tokamak discharges, also produced in the RFX-mod device. MHD modes exhibit toroidal rotation at a frequency depending on mode amplitude. Differently from what encountered in RFP plasmas at comparable current levels, no wall locking is detected.

We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases. 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. Peer Reviewed Article signat per 497 autors/es: Thomas Sunn Pedersen1,2,∗ , I. Abramovic3, P. Agostinetti4, M. Agredano Torres1, S. Äkäslompolo1, J. Alcuson Belloso1, P. Aleynikov1, K. Aleynikova1, M. Alhashimi1, A. Ali1, N. Allen5, A. Alonso6, G. Anda7, T. Andreeva1, C. Angioni8, A. Arkhipov8, A. Arnold1, W. Asad8, E. Ascasibar6, M.-H. Aumeunier9, K. Avramidis10, E. Aymerich11, S.-G. Baek3, J. Bähner1, A. Baillod12, M. Balden1, M. Balden8, J. Baldzuhn1, S. Ballinger3, M. Banduch1, S. Bannmann1, A. Banon Navarro8, A. Bañon Navarro ´ 1, T. Barbui13, C. Beidler1, C. Belafdil9, A. Bencze7, A. Benndorf1, M. Beurskens1, C. Biedermann1, O. Biletskyi14, B. Blackwell15, M. Blatzheim1, T. Bluhm1, D. Böckenhoff1, G. Bongiovi16, M. Borchardt1, D. Borodin17, J. Boscary8, H. Bosch1,18, T. Bosmann19, B. Böswirth8, L. Böttger1, A. Bottino8, S. Bozhenkov1, R. Brakel1, C. Brandt1, T. Bräuer1, H. Braune1, S. Brezinsek17, K. Brunner1, S. Buller1, R. Burhenn1, R. Bussiahn1, B. Buttenschön1, A. Buzás7, V. Bykov1, I. Calvo6, K. Camacho Mata1, I. Caminal20, B. Cannas11, A. Cappa6, A. Carls1, F. Carovani1, M. Carr21, D. Carralero6, B. Carvalho22, J. Casas20, D. Castano-Bardawil17, F. Castejon6, N. Chaudhary1, I. Chelis23, A. Chomiczewska24, J.W. Coenen13,17, M. Cole1, F. Cordella25, Y. Corre9, K. Crombe26, G. Cseh7, B. Csillag7, H. Damm1, C. Day10, M. de Baar27, E. De la Cal6, S. Degenkolbe1, A. Demby13, S. Denk3, C. Dhard1, A. Di Siena8,28, A. Dinklage12, T. Dittmar17, M. Dreval14, M. Drevlak1, P. Drewelow1, P. Drews17, D. Dunai7, E. Edlund3, F. Effenberg29, G. Ehrke1, M. Endler1, D.A. Ennis5, F.J. Escoto6, T. Estrada6, E. Fable8, N. Fahrenkamp1, A. Fanni11, J. Faustin1, J. Fellinger1, Y. Feng1, W. Figacz4, E. Flom13, O. Ford1, T. Fornal24, H. Frerichs13, S. Freundt1, G. Fuchert1, M. Fukuyama30, F. Füllenbach1, G. Gantenbein10, Y. Gao1, K. Garcia13, J.M. García Regaña6, I. García-Cortés6, J. Gaspar31, D.A. Gates29, J. Geiger1, B. Geiger13, L. Giudicotti32, A. González6, A. Goriaev26,33, D. Gradic1, M. Grahl1, J.P. Graves12, J. Green13, E. Grelier9, H. Greuner8, S. Groß1, H. Grote1, M. Groth34, M. Gruca24, O. Grulke1,35, M. Grün1, J. Guerrero Arnaiz1, S. Günter8, V. Haak1, M. Haas1, P. Hacker1, A. Hakola36, A. Hallenbert1, K. Hammond29, X. Han17,37, S.K. Hansen3, J.H. Harris38, H. Hartfuß1, D. Hartmann1, D. Hathiramani1, R. Hatzky8, J. Hawke39, S. Hegedus7, B. Hein8, B. Heinemann8, P. Helander12, S. Henneberg1, U. Hergenhahn8,40, C. Hidalgo6, F. Hindenlang8, M. Hirsch1, U. Höfel1, K.P. Hollfeld17, A. Holtz1, D. Hopf8, D. Höschen17, M. Houry9, J. Howard19, X. Huang41, M. Hubeny17, S. Hudson29, K. Ida9, Y. Igitkhanov10, V. Igochine8, S. Illy10, C. Ionita-Schrittwieser42, M. Isobe39, M. Jabłczynska ´ 24, S. Jablonski24, B. Jagielski1, M. Jakubowski1, A. Jansen van Vuuren1, J. Jelonnek10, F. Jenko8, F. Jenko8, T. Jensen35, H. Jenzsch1, P. Junghanns8, J. Kaczmarczyk24, J. Kallmeyer1, U. Kamionka1, M. Kandler8, S. Kasilov43, Y. Kazakov26, D. Kennedy1, A. Kharwandikar1, M. Khokhlov1, C. Kiefer8, C. Killer1, A. Kirschner17, R. Kleiber1, T. Klinger12, S. Klose1, J. Knauer1, A. Knieps17, F. Köchl44, G. Kocsis7, Ya.I. Kolesnichenko45, A. Könies1, R. König1, J. Kontula34, P. Kornejew1, J. Koschinsky, M.M. Kozulia14, A. Krämer-Flecken17, R. Krampitz1, M. Krause1, N. Krawczyk24, T. Kremeyer1, L. Krier10, D.M. Kriete5, M. Krychowiak1, I. Ksiazek46, M. Kubkowska24, M. Kuczynski1, G. Kühner1, A. Kumar15, T. Kurki-Suonio34, S. Kwak1, M. Landreman47, P.T. Lang8, A. Langenberg1, H.P. Laqua12, H. Laqua1, R. Laube1, S. Lazerson1, M. Lewerentz1, C. Li17, Y. Liang17, Ch. Linsmeier17, J. Lion1, A. Litnovsky17,48, S. Liu37, J. Lobsien1, J. Loizu12, J. Lore38, A. Lorenz1, U. Losada6, F. Louche26, R. Lunsford29, V. Lutsenko45, M. Machielsen12, F. Mackel8, J. Maisano-Brown3, O. Maj8, D. Makowski49, G. Manduchi50, E. Maragkoudakis6, O. Marchuk17, S. Marsen1, E. Martines4, J. Martinez-Fernandez6, M. Marushchenko1, S. Masuzaki41, D. Maurer5, M. Mayer8, K.J. McCarthy6, O. Mccormack4, P. McNeely1, H. Meister8, B. Mendelevitch8, S. Mendes1, A. Merlo1, A. Messian26, A. Mielczarek49, O. Mishchenko1, B. Missal1, R. Mitteau9, V.E. Moiseenko14, A. Mollen1, V. Moncada9, T. Mönnich1, T. Morisaki41, D. Moseev1, G. Motojima41, S. Mulas6, M. Mulsow1, M. Nagel1, D. Naujoks1, V. Naulin35, T. Neelis19, H. Neilson29, R. Neu8, O. Neubauer17, U. Neuner1, D. Nicolai17, S.K. Nielsen35, H. Niemann1, T. Nishiza1, T. Nishizawa1, T. Nishizawa8, C. Nührenberg1, R. Ochoukov8, J. Oelmann17, G. Offermanns17 K. Ogawa41, S. Okamura41, J. Ölmanns17, J. Ongena26, J. Oosterbeek1, M. Otte1, N. Pablant29, N. Panadero Alvarez6, N. Panadero Alvarez6, A. Pandey1, E. Pasch1, R. Pavlichenko14, A. Pavone1, E. Pawelec46, G. Pechstein1, G. Pelka24, V. Perseo1, B. Peterson41, D. Pilopp1, S. Pingel1, F. Pisano11, B. Plöckl8, G. Plunk1, P. Pölöskei1, B. Pompe2, A. Popov51, M. Porkolab3, J. Proll19, M.J. Pueschel19,27, M.-E. Puiatti52, A. Puig Sitjes1, F. Purps1, K. Rahbarnia1, M. Rasinski ´ 17, J. Rasmussen35, A. Reiman29, F. Reimold1, M. Reisner8, D. Reiter17, M. Richou9, R. Riedl8, J. Riemann1, K. Riße1, G. Roberg-Clark1, V. Rohde8, J. Romazanov17, D. Rondeshagen1, P. Rong1, L. Rudischhauser1, T. Rummel1, K. Rummel1, A. Runov1, N. Rust1, L. Ryc24, P. Salembier20, M. Salewski35, E. Sanchez6, S. Satake41, G. Satheeswaran17, J. Schacht1, E. Scharff1, F. Schauer8, J. Schilling1, G. Schlisio1, K. Schmid8, J. Schmitt5, O. Schmitz13, W. Schneider1, M. Schneider1, P. Schneider8, R. Schrittwieser42, T. Schröder1, M. Schröder1, R. Schroeder1, B. Schweer26, D. Schwörer1, E. Scott1, E. Scott8, B. Shanahan1, G. Sias11, P. Sichta29, M. Singer1, P. Sinha29, S. Sipliä34, C. Slaby1, M. Sleczka53, H. Smith1, J. Smoniewski54, E. Sonnendrücker8, M. Spolaore4, A. Spring1, R. Stadler8, D. Stanczak24, T. Stange1, I. Stepanov26, L. Stephey13, J. Stober8, U. Stroth8,55, E. Strumberger8, C. Suzuki41, Y. Suzuki41, J. Svensson1, T. Szabolics7, T. Szepesi7, M. Szücs7, F.L. Tabares6, N. Tamura41, A. Tancetti35, C. Tantos10, J. Terry3, H. Thienpondt6, H. Thomsen1, M. Thumm10, J.M. Travere9, P. Traverso5, J. Tretter8, E. Trier8, H. Trimino Mora1, T. Tsujimura41, Y. Turkin1, A. Tykhyi45, B. Unterberg17, P. van Eeten1, B.Ph. van Milligen6, M. van Schoor26, L. Vano1, S. Varoutis10, M. Vecsei7, L. Vela56, J.L. Velasco6, M. Vervier17, N. Vianello50, H. Viebke1, R. Vilbrandt1, G. Vogel8, N. Vogt1, C. Volkhausen1, A. von Stechow1, F. Wagner1, E. Wang17, H. Wang57, F. Warmer1, T. Wauters26, L. Wegener1, T. Wegner1, G. Weir1, U. Wenzel1, A. White3, F. Wilde1, F. Wilms1, T. Windisch1, M. Winkler1, A. Winter1, V. Winters1, R. Wolf118, A.M. Wright29, G.A. Wurden39, P. Xanthopoulos1, S. Xu17, H. Yamada58, H. Yamaguchi41, M. Yokoyama41, M. Yoshinuma41, Q. Yu8, M. Zamanov14, M. Zanini1, M. Zarnstorff29, D. Zhang1, S. Zhou17, J. Zhu1, C. Zhu29, M. Zilker8, A. Zocco1, H. Zohm8, S. Zoletnik7 and L. Zsuga7 // 1 Max Planck Institute for Plasma Physics, Garching and Greifswald, Germany: 2 University of Greifswald, Greifswald, Germany; 3 Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, United States of America; 4 Consorzio RFX, Corso Stati Uniti, 4-35127 Padova, Italy; 5 Auburn University, Auburn, AL 36849, United States of America; 6 CIEMAT, Avenida Complutense, 40, 28040 Madrid, Spain; 7 Center for Energy Research, Konkoly-Thegeut 29-33, 1121 Budapest, Hungary; 8 Max-Planck-Institute for Plasma Physics, Boltzmannstraße 2, 85748 Garching bei München, Germany; 9 CEA Cadarache, 13115 Saint-Paul-lez-Durance, France; 10 Karlsruhe Institute of Technology, Kaiserstr. 12, 76131 Karlsruhe, Germany; 11 University of Cagliari, Via Universita, 40, 09124 Cagliari, Italy; 12 École Polytechnique Fédérale de Lausanne, Swiss Plasma Center, CH-1015 Lausanne, Switzerland; 13 University of Wisconsin–Madison, Engineering Drive, Madison, WI 53706, United States of America; 14 Institute of Plasma Physics, National Science Center ‘Kharkiv Institute of Physics and Technology’, Kharkiv, Ukraine; 15 The Australian National University, Acton ACT 2601, Canberra, Australia; 16 Department of Engineering, University of Palermo, Viale delle Scienze, Edificio 6, Palermo, 90128, Italy; 17 Forschungszentrum Jülich GmbH, Institut für Energie-und Klimaforschung—Plasmaphysik, 52425 Jülich, Germany; 18 Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany; 19 Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands; 20 Universitat Politècnica de Catalunya. BarcelonaTech, C. Jordi Girona, 31, 08034 Barcelona, Spain; 21 Culham Center for Fusion Energy, Abingdon OX14 3EB, United Kingdom; 22 Instituto de Plasmas e Fusao Nuclear, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; 23 Department of Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece; 24 Institute of Plasma Physics and Laser Microfusion, 23 Hery Str., 01-497 Warsaw, Poland; 25 ENEA—Centro Ricerche Frascati, Via Enrico Fermi, 45, 00044 Frascati RM, Italy; 26 Laboratory for Plasma Physics, LPP-ERM/KMS, TEC Partner, B-1000 Brussels, Belgium; 27 Dutch Institute for Fundamental Energy Research, PO Box 6336, 5600 HH Eindhoven, Netherlands; 28 University of Texas, Austin, TX, United States of America; 29 Princeton Plasma Physics Laboratory, Princeton, NJ 08543, United States of America; 30 Kyushu University, 744 Motooka Nishi-ku, Fukuoka 819-0395, Japan; 31 Aix-Marseille University, Jardin du Pharo, 58 Boulevard Charles Livon, 13007, Marseille, France; 32 Department of Physics and Astronomy, Padova University, Via Marzolo 8, 35131 Padova, Italy; 33 Department of Applied Physics, Ghent University, Sint-Pietersnieuwstraat 41 B4, 9000 Ghent, Belgium; 34 Aalto University, 02150 Espoo, Finland; 35 Department of Physics, Technical University of Denmark, Anker Engelunds Vej, 2800 Kgs Lyngby, Denmark; 36 VTT Technical Research Center of Finland Ltd., PO Box 1000, FI-02044 VTT, Finland; 37 Institute of Plasma Physics, Chinese Academy of Sciences, 230031 Hefei, Anhui, China; 38 Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37830, United States of America; 39 Los Alamos National Laboratory, NM 87545, United States of America; 40 Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany; 41 National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki, Gifu Prefecture 509-5292, Japan; 42 Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria; 43 Graz University of Technology, Rechbauerstraße 12, 8010 GRAZ, Austria; 44 Austrian Academy of Science, Doktor-Ignaz-Seipel-Platz 2, 1010 Wien, Austria; 45 Institute for Nuclear Research, prospekt Nauky 47, Kyiv 03028, Ukraine; 46 University of Opole, plac Kopernika 11a, 45-001 Opole, Poland; 47 University of Maryland, Paint Branch Drive, College Park, MA 20742, United States of America; 48 National Research Nuclear University MEPhI, 115409 Moscow, Russian Federation; 49 Department of Microelectronics and Computer Science, Lodz University of Technology, Wolczanska 221/223, 90-924 Lodz, Poland; 50 Consiglio Nazionale delle Ricerche, Piazzale Aldo Moro, 7, 00185 Roma, Italy; 51 Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Politekhnicheskaya, St Petersburg 194021, Russian Federation; 52 Istituto di Fisica del Plasma Piero Caldirola, Via Roberto Cozzi, 53, 20125 Milano, Italy; 53 University of Szczecin, 70-453, aleja Papieza Jana Pawła II 22A, Szczecin, Poland; 54 Lawrence University, 711 E Boldt Way, Appleton, WI 54911, United States of America; 55 Physik-Department E28, Technische Universität München, 85747 Garching, Germany; 56 Universidad Carlos III de Madrid, Av. de la Universidad, 30 Madrid, Spain; 57 Yale University, New Haven, CT 06520, United States of America; 58 University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chhiab 277-0882, Japan Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant Objectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.a - Per a 2030, augmentar la cooperació internacional per tal de facilitar l’accés a la investigació i a les tecnolo­gies energètiques no contaminants, incloses les fonts d’energia renovables, l’eficiència energètica i les tecnologies de combustibles fòssils avançades i menys contaminants, i promoure la inversió en infraestructures energètiques i tecnologies d’energia no contaminant

We present a study of the fast, spontaneous rotation regime of tearing modes (TM) in the RFX-mod circular tokamak discharges. Integrated analyses of magnetic, flow and kinetic measurements, are discussed. This analysis of rotation frequency components related to the ion flow and diamagnetic drift shows that the TM fast rotation is mainly driven by the diamagnetic drift. The global decrease of the temperature profile, induced by a growing mode amplitude, can explain the slowing-down of the rotation, which in turn can trigger a potentially disruptive sequence. We show that in RFX-mod the slowing-down cannot be explained solely on the basis of the electromagnetic torque with the external conductive structures, as often reported in literature from other experiments. This analysis, indeed, suggests a strong relationship between the TM dynamics and the transport physics. Statistical analysis of disruptions with slowing down of island rotation shows that TMs take a part in the disruption, even without a locking to the wall.

Zusammenfassung Hintergrund Die Integrität der Augenoberfläche und die Transparenz der Hornhaut als „Fenster des Auges“ sind Voraussetzungen für die Erzielung einer sehr guten Sehkraft, einem Körpersinn mit zentraler Bedeutung für Lebensqualität und für soziale oder berufliche Teilnahme am gesellschaftlichen Umfeld. Die Homöostase an der Augenoberfläche ist ständig durch Mikroben und durch intrinsische Faktoren mit negativen Auswirkungen auf die Wundheilung bedroht (z. B. metabolische Störungen wie Diabetes mellitus). Zudem stellt die weite Verbreitung von Kontaktlinsen ein beachtliches Risiko für mikrobielle Infektionen durch mangelnde Hygiene dar. In fortgeschrittenen Stadien können Keratitiden mit kornealen Defekten einhergehen und durch assoziierten Stromaverlust zur Perforation der Hornhaut führen. Gegenwärtige Behandlungsansätze beinhalten topische und systemische Anwendungen von Antibiotika oder Antimykotika und bedürfen in schwereren Fällen der stationären Behandlung. Patienten/Material und Methoden Manche Mikroben können therapierefraktär oder -resistent sein und daher eine Verschlechterung des klinischen Befunds verursachen. In der vorgelegten Untersuchung wurden der Effekt von Kaltplasma hinsichtlich der Reduktion der Erregerlast in vitro, im Gewebe ex vivo sowie bei einem therapierefraktären Ulkus untersucht. Kaltplasma ist elektrisch ionisiertes Gas, das grundsätzlich zur Oxidation und Entkeimung von Luft, Oberflächen, OP-Instrumenten oder Geweben eingesetzt wird. In der Natur unter anderem von Blitzen und Polarlichtern vorkommend, sind künstlich hergestellte Plasmen von Neonröhren und dem Schweißen bekannt. Ergebnisse In vitro, ex vivo sowie bei der Behandlung eines therapierefraktären Hornhautgeschwürs konnte die Reduktion der Erregerlast bzw. eine Besserung des klinischen Befunds gezeigt werden. Schlussfolgerung Plasmamedizin und ihre desinfizierenden Eigenschaften können neue Ansätze in der Behandlung mikrobieller Hornhautinfektionen eröffnen. Dies kann zu einer Verkürzung der Behandlungszeit, zu einer schnelleren Erholung des Patienten sowie insgesamt zu einer Senkung der Kosten für Gesundheitssysteme führen.

The morphology, microstructure and chemical composition of soot particles emitted directly from biofuel cook stoves have been studied by using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and ion beam analysis (IBA) techniques. Freshly emitted soot particles were collected using an eight stage cascade impactor that separates particles according to their size. The particulate matter is impacted on thin aluminum foil and copper grids for Transmission Electron Microscope. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot chain. Results from the border-based fractal dimension indicated that main morphological differences observed in soot particles perhaps are associated to cook-stove chamber design. XPS analysis shows that particles are mainly composed by carbon and oxygen. The XPS C-1s spectra show carbon with three peaks corresponding to sp 2 , sp 3 hybridization and carbon oxygen bond. Additionally, we determined the areal density (atoms/cm 2 ) of the soot films and the purity of the substrates by means of IBA techniques.

Based on the weighing of samples before and after drying, the drying in oven method is widely used to measure the moisture content in solid materials. Time and temperature are some of the most important conditions for the application of this method, which frequently are unknown and must be determined experimentally or by another method. However, it is known that experimental processes are time-consuming and require excessive amounts of energy. A less expensive and faster option is the use of mathematical models to describe the heat and moisture transfer in the drying process, where several models apply. The Luikov’s model is one of the most accepted of them since it has a wide application in the calculation of drying curves of solid materials. This model consists in a coupled system of nonlinear partial differential equations which is derived from thermodynamics principles of irreversible processes, laws of energy and mass conservation and also the diffusion of heat and mass law. The solution to the Luikov’s model for the one-dimensional case was obtained using a method proposed by Lui et al., applied to several solid materials. In this paper, the drying curves for red brick and wood are presented and compared with those obtained experimentally. Finally, the drying curves were used to determine the sample’s moisture content and the corresponding uncertainty was estimated as well.

Sorption isotherms relate the equilibrium condition between the moisture content of a solid material and the relative humidity of ambient where such material is placed. Isotherms are useful in many fields where the water vapor of ambient affects the properties of materials. In particular, the information given by the sorption isotherms is useful in the moisture conditioning of solid materials, which are used for the calibration of moisture meters for grains, cereals and wood, among others. There are many isotherm models (almost one for each material). However, most of them do not estimate the uncertainty or, in some cases, the estimation is incomplete. On the other hand, the most known method for uncertainty evaluation is given by the Guide to the Expression of Uncertainty in Measurement (GUM). However, this guide has some restrictions to be satisfactorily used; for example, the model of measurand must be linear and have a known probability distribution function for the model inputs and similar uncertainty values. So often, the sorption isotherm models used for grains are highly nonlinear. Therefore, the GUM could not provide reliable results. To overcome this, an alternative method is the use of Monte Carlo simulation method, which is suggested for nonlinear models in the GUM supplement. In this paper, the uncertainty estimation was done with the GUM and Monte Carlo methods applied to some sorption isotherms, which are used for grains and cereals. The results with both methods showed some discrepancies, which are due mainly to the nonlinearity of models.

Integrity of the ocular surface and transparency of the cornea as "window of the eye," necessary to achieve a good visual acuity, are essential of every persons' quality of life and for their ability to professionally and socially interact in the community. The homeostasis at the ocular surface is constantly endangered both by microbes and by intrinsic factors, such as metabolic disturbances (e.g., diabetes) reducing the wound healing capability. In addition, the popular use of contact lenses poses a considerable risk for microbial infection due to poor hygiene or overwearing. Infections at the ocular surface clinically present as infections of the conjunctiva (=conjunctivitis) or of the cornea (=keratitis). In advanced stages, corneal defects can result with loss of stromal tissue and potential risk of perforation of the eye. Current treatments involve topical or i.v. use of e.g., antibiotics or of antimycotics and require hospitalization in severe cases. However, some microbes can be therapy-refractive or even -resistent leading to worsening of the clinical situation. Plasma medicine and its desinfective properties open new ways for treatment of microbial infections of the cornea. This can lead to shortening of treatment time, faster recovery for the patient and to an overall reduction of costs for health systems. Perspectives in Ophthalmology | Request PDF. Available from: https://www.researchgate.net/publication/324947475_Perspectives_in_Ophthalmology.

Background Skin wound healing includes a system of biological processes, collectively restoring the integrity of the skin after injury. Healing by second intention refers to repair of large and deep wounds where the tissue edges cannot be approximated and substantial scarring is often observed. The objective of this study was to evaluate the effects of mesenchymal stem cells (MSCs) in second intention healing using a surgical wound model in sheep. MSCs are known to contribute to the inflammatory, proliferative, and remodeling phases of the skin regeneration process in rodent models, but data are lacking for large animal models. This study used three different approaches (clinical, histopathological, and molecular analysis) to assess the putative action of allogeneic MSCs at 15 and 42 days after lesion creation. Results At 15 days post-lesion, the wounds treated with MSCs showed a higher degree of wound closure, a higher percentage of re-epithelialization, proliferation, neovascularization and increased contraction in comparison to a control group. At 42 days, the wounds treated with MSCs had more mature and denser cutaneous adnexa compared to the control group. The MSCs-treated group showed an absence of inflammation and expression of CD3+ and CD20+. Moreover, the mRNA expression of hair-keratine (hKER) was observed in the MSCs-treated group 15 days after wound creation and had increased significantly by 42 days post-wound creation. Collagen1 gene (Col1α1) expression was also greater in the MSCs-treated group compared to the control group at both days 15 and 42. Conclusion Peripheral blood-derived MSCs may improve the quality of wound healing both for superficial injuries and deep lesions. MSCs did not induce an inflammatory response and accelerated the appearance of granulation tissue, neovascularization, structural proteins, and skin adnexa.

Many instruments used for measuring of moisture content in solid materials, such as thermobalances and Karl Fisher titrators, require calibration or verification. The calibration could be performed by using some hydrated ionic compounds [such as lactose monohydrate, sodium tartrate dihydrate (STDH), potassium citrate monohydrate (PCMH), among others], which require the certification in their moisture content value. The moisture content of these compounds could be obtained theoretically, however there are few published papers about the measured values and their uncertainty. The measurement of moisture content of these materials could be performed by the oven drying method. In this work, the measurement process of the moisture content of STDH and PCMH using a forced convection drying oven is described. The obtained results are showing that is possible to reach uncertainties smaller than 0.06 % (k = 1) of moisture content for these compounds, whose values are good enough for the calibration and verification of thermobalances and Karl Fisher equipments.

Infectious keratitis of the eye is induced by proliferation and penetration of microorganisms in the cornea. The possibility of developing a novel treatment for this condition based on the action of a low temperature, atmospheric pressure plasma is presented. In-vitro results show that bacteria and fungi responsible of keratitis are inactivated by the exposure to the afterglow of a RF plasma produced in a helium flow mixed with ambient air. On the contrary, the viability of corneal cells is not significantly affected. Furthermore, no DNA damage has been detected in the treated cells, suggesting that no long time effects might be induced by this kind of treatment. An increase of intracellular Reactive Oxygen Species (ROS) has been measured following the treatment, suggesting that these chemicals can be involved in the plasma-induced effects. Overall, the presented results point to the feasibility of a plasma-based treatment for infectious keratitis.

This paper reports the main results of the RFX-mod fusion science activity since the last 2014 IAEA Fusion Energy Conference. The RFX-mod device is characterized by a unique flexibility in terms of accessible magnetic configurations. Axisymmetric and helically shaped Reversed-field pinch equilibria have been studied, along with tokamak plasmas in a wide range of q(a) regimes (spanning from 4 down to 1.2 values). The full range of magnetic configurations in between the two, the so-called ultra low-q ones, has been explored, with the aim of studying specific physical issues common to all equilibria, such as, for example, the density limit phenomenon. The powerful RFX-mod feedback control system has been exploited for MHD control, which allowed to extend the range of experimental parameters, as well as to induce specific magnetic perturbations for the study of 3D effects. In particular, transport, edge and isotope effect in 3D equilibria have been investigated, along with runaway mitigations through induced magnetic perturbations. The first transitions to H-mode in circular and D-shaped tokamak plasmas have been obtained thanks to an active modification of the edge electric field through a polarized electrode. The experiments are supported by intense modelling with 3D MHD, gyrokinetic, guiding center and transport codes. Proposed modifications to the RFX-mod device, which will enable further contributions to the solution of key issues in the roadmap to ITER and DEMO, are also briefly presented.

Coherent structures emerging from the background turbulence have been detected by electrostatic measurements in the edge region of two Reversed Field Pinch experiments, RFX (Padua) and Extrap-T2R (Stockholm). Measurements have been performed by arrays of Langmuir probes which allowed simultaneous measurements of temperature, potential and density to be carried out. These structures have been interpreted as a dynamic balance of dipolar and monopolar vortices, whose relative population are found to depend on the local mean E × B flow shear. The contribution to the anomalous transport of these structures has been investigated and it has been found that the corresponding diffusion coeffcient accounts up to 50% of the total diffusivity. The experimental findings indicate that the diffusion coeffcient associated to the coherent structures depends on the relative population of the two types of vortices and is minimum when the two populations are equal. An interpretative model is proposed to explain this feature.

High frequency coherent magnetic fluctuations related to the type I edge localized mode (ELM) cycle have been found in ASDEX Upgrade. Typical frequencies are in the range 300-500 kHz, and the poloidal mode number, m, measured at the outboard midplane, is estimated to be 10-15. These MHD modes are present in many low density (low collisionality) discharges, while they have not been found in high density ones yet. New findings on already known low frequency type I ELM precursors confirm that in ASDEX Upgrade type I ELM mode precursors are normally phase locked to the wall in discharges with NBI heating parallel to and in the direction of the plasma current (co-injection) and can be seen with a non-zero rotation frequency only in shots with anti-parallel NBI (counter-injection). Additional information is given by ECE data. The existence of low and high frequency MHD events suggests an interpretation in the framework of the peeling-ballooning model. The high frequency magnetic activity seems to be related strictly to the increase in (and eventual saturation of) edge electron temperature, while low frequency modes are related directly to the ELM crash itself.

This overview of results from the MST reversed field pinch program summarizes physics im- portant for the advancement of the RFP as well as for improved understanding of toroidal magnetic confinement in general. Topics include energetic particle effects, 3D helical equilibria, and density limit studies, microturbulence, ion heating, and magnetic self-organization physics. With neutral beam injection, several bursty energetic particle (EP) modes are observed. The profiles of the magnetic and density fluctuations associated with these EP-modes are measured using an FIR interferometer- polarimeter. Equilibrium reconstructions of the quasi-single-helicity 3D helical state are provided by the V3FIT code that now incorporates several of MST's advanced diagnostics. A predator-prey theoretical model based on sheared flow and/or magnetic field has been developed that captures key QSH dynamics. Upgraded pellet injection permits study of density and limits over MST's full range of operation, and an MST-record line-average density of 0 : 9 10 20 { m 3 ( n { n G 1 : 4 ) has been obtained. Plasma exhibits saturation at tot § 20% for a wide range of density, 0 : 2 + n { n G + 1 : 6 . Gyrokinetic simulations (GENE) based on experimental toroidal equilibrium reconstructions predict unstable trapped electron modes. Nonlinear simulations show that the "Dimits shift" is large and persists at finite . Experimentally, small-scale density fluctuations are detected in improved confine- ment plasmas. Impurity ion temperature measurements reveal a charge-to-mass-ratio dependence in the rapid heating that occurs during a sawtooth crash. Also, a toroidal asymmetry in the ion temper- ature is measured, correlated with 3D magnetic structure associated with tearing modes. Magnetic self-organization studies include measurements and modeling of the dynamo emf in standard RFP operation as well as with an applied ac inductive electric field to investigate the dynamics of oscillating field current drive (OFCD). Extended MHD computation for standard RFP conditions using NIMROD predicts dynamical coupling of current and plasma flow relaxation. The dynamo emf has also been measured when OFCD is applied, strengthening the understanding of and possibility for steady-state current sustainment using inductive current drive.

A Neutral Particle Analyzer (NPA) of the ACORD series, developed by theIOFFE Institute of the Russian Academy of Sciences has been put in operation in the RFX-mod device. It resolves the energy distribution of the neutral hydrogen particles produced by charge exchange (CX) processes and leaving the plasma. A first estimate of the ion temperature Ti is deduced from the logarithmic slope of collected spectra. A more detailed calculation of Ti is performed according to the method suggested in Schlatter, PPCF 2006.. The method gives information on the ion temperature profile matching the experimental and the calculated spectrum of particle flux, taking also into accountthe effect on the neutral spectrum of the attenuation processes. The density and the energy of both first generation and energetic neutrals are calculated with the MonteCarlo code Nenè The analyses show a dependence of the ion temperature on the plasma density. At low density (ne1e-20m-3) reaching 600-700eV, suggesting the presence of an anomalous ion heating mechanism. It is worth noting that in this density regime the measurements of NPA refer to the external region (r/a ~0.8). The temperature of impurities is estimated from Doppler broadening spectroscopic measurements. A good agreement is found between the hydrogen and the CV and BV (associated radial positions averaged on the emissivity profile r/a~0.8-0.9 and r/a~0.6-0.7) ion temperatures at low density, while at higher density the impurity temperature is weakly decreasing with the density and never exceeds 300 eV. Further insight is expected from the measurements of neutron flux that will be performed during discharges in deuterium which are planned in the next experimental campaign in RFX-mod.

Sophisticated multi-chord diagnostics have been developed on RFX-Mod and MST for soft x-ray (SXR) emissivity and electron temperature (Te) profile measurements. Quasi Single Helicity (QSH) plasmas, where a single m=1 tearing mode dominates the MHD magnetic spectrum, have been analyzed. To improve the SXR and Te profile reconstructions in the presence of QSH, algorithms that reproduce the magnetic topology have been developed to map the measurements on flux surfaces. In RFX-Mod the analysis shows a strong correlation between magnetic QSH and the appearance of a SXR structure in the emissivity distribution. The SXR structure corresponds to a thermal structure in the Te profile. Differences in the temperature gradient between the rising phase and the flattop phase of QSH have been analyzed. In the rising phase the gradient increases and the thermal structure grows in size. During the flattop phase, where the dominant mode amplitude is constant, the structure is intermittent, with several crashes that make the Te profile flatter. Similar measurements at MST confirm the correspondence between QSH and SXR structure. The analysis shows that this structure can be correlated with a thermal structure but that also impurity could play an important role.

The effects of non-axysimmetric magnetic field or magnetic field ergodization on the external region of the plasma is becoming a fundamental issue in the fusion community, both for intrinsic 3D configuration such as stellarators [1], and previously assumed 2D ones such as tokamaks, where magnetic perturbations are used for ELM control [2]. Interesting analogies can be drawn with the helical configuration observed in high-current regimes in RFPs [3] where the small residual helical ripple is sufficient to modulate all the kinetic properties of the edge [4]. Aim of the contribution is to present the most recent experimental results and physical interpretation of the phenomena observed in the edge region of the RFX-mod experiment, with a strong emphasis on the effects of helical deformation on the flow and turbulence. The symmetry breaking caused by the presence of a non axy-symmetric perturbation causes the appearance of an E B flow as a result of ambipolar response to balance different ion/electron diffusion. The detailed phase relationship between electric field and magnetic perturbation is in-vestigated, and to correctly handle the intrinsic 3D configuration we introduce the helical angle u m;n = mq n? ?m;n where ?m;n is the proper mode phase. The chosen framework correctly highlights the helical dependence of the plasma parameters on the existing perturbation. Ex-perimental evidences of the modulation of flow and turbulence properties, in terms of radial electric field ripple, parallel current perturbation, blobs dimension and intrinsic vorticity will be reported. The contribution will try to highlight similarities and differences between helical RFP bound-ary and analogous investigation in Tokamak RMP experiments in order to underline the benefi-cial effects arising from cross-device comparison of similar physical problems. 1 R König et al., Plasma Physics and Controlled Fusion 44, 2365 (2002). 2 T. E. Evans et al., Nature Physics 2, 419-423 (2006). 3 R Lorenzini et al., Nature Physics 5, 570-754 (2009). 4 N Vianello et al., to be published in Nuclear Fusion (2013).

Reconstruction of the soft x - ray (SXR) emissivity map is an important tool in fusion devices due to the tight link with transport and Magnetohydrodynamic (MHD) equilibrium. A notable example is the occurrence of helical magnetic self - organized structures in the core of the reversed field pinch during Quasi Single Helicity (QSH) plasmas, when a single m=1 tearing mode dominates the MHD magnetic spectrum and all remaining modes have reduced amplitudes. More valuable information can be obtained taking into account the strong dependence of the continuum SXR radiation on electron temperature T e : the direct - brightness two - color technique can be applied to line integrated measurement s to obtain the T e along the designed lines of sight. A sophisticated multi - chord diagnostic has been developed on RFX - Mod for SXR emissivity and electron temperature profiles measurements, with good spatial and temporal resolution to identify helical stru ctures and track fast events [1] . An advanced instrument, similar to that of RFX - Mod, has been designed and installed also on MST [2] . This allows the study of QSH plasmas in both RFPs. To improve the SXR and T e data reconstruction in the presence of helical magne tic equilibria, mapping algorithms that reproduce the magnetic topology during the QSH regimes have been developed to map the measurements on flux surfaces. The analysis shows, in RFX - Mod, a clear difference in the temperature gradient (related to the pres ence of transport barriers) between the rising phase of QSH and the saturated (or flattop) phase. In the rising phase a correlation of temperature gradient with magnetic spectrum is found , showing a positive trend between dominant mode amplitude and therma l structure dimension, as well as a negative correlation of secondary modes amplitudes and temperature gradient. On the other hand, in the flattop phase the presence of a thermal structure is intermittent, with several crashes and flattening of the profile , and much less influenced by the magnetic dynamics. On the other hand, measurements at MST confirm the correlation between magnetic QSH and the appearance of a SXR structure in the emissivity distribution, but no clear indication of a thermal structure in the Te profile has been found, indicating a different origin of the SXR island. References [1] P. Franz, et al. , Nucl. Fusion, 53 053011 (2013) [2] M. B. McGarry, et al. , Rev. Sci. Instrum. 83 , 10E129 (2012)

An overview of recent results from the MST programme on physics important for the advancement of the reversed field pinch (RFP) as well as for improved understanding of toroidal magnetic confinement more generally is reported. Evidence for the classical confinement of ions in the RFP is provided by analysis of impurity ions and energetic ions created by 1 MW neutral beam injection (NBI). The first appearance of energetic-particle-driven modes by NBI in a RFP plasma is described. MST plasmas robustly access the quasi-single-helicity state that has commonalities to the stellarator and 'snake' formation in tokamaks. In MST the dominant mode grows to 8% of the axisymmetric field strength, while the remaining modes are reduced. Predictive capability for tearing mode behaviour has been improved through nonlinear, 3D, resistive magnetohydrodynamic computation using the measured resistivity profile and Lundquist number, which reproduces the sawtooth cycle dynamics. Experimental evidence and computational analysis indicates two-fluid effects, e.g., Hall physics and gyro-viscosity, are needed to understand the coupling of parallel momentum transport and current profile relaxation. Large Reynolds and Maxwell stresses, plus separately measured kinetic stress, indicate an intricate momentum balance and a possible origin for MST's intrinsic plasma rotation. Gyrokinetic analysis indicates that micro-tearing modes can be unstable at high beta, with a critical gradient for the electron temperature that is larger than for tokamak plasmas by roughly the aspect ratio.

In the reversed-field pinch (RFP) plasmas the Quasi Single Helicity (QSH) scenario features a central plasma volume with good magnetic surfaces and appearance of transport barriers with reduced heat transport. As for the other classes of fusion devices, in such plasmas microturbulence is invoked as responsible for a non-negligible level of transport beyond collisional limits. Recently, a theoretical stability analysis performed by means of the gyrokinetic GS2 code revealed the QSH states of the RFP to be prone to microtearing modes [1]. Despite the body of theoretical work on microturbulence in fusion plasmas, up to now most proofs about the existence of the microturbulence are deduced only from measurements of large-scale quantities (profiles, fluxes, flows, etc...), and the relation between the micro- and the macro-scales needs supplementary hypotheses. We provide here direct observations of the presence of microtearing modes in the plasma core of a fusion device. The measurements are carried out in the RFX-mod device by means of a system of in-vessel probes located at the wall detecting magnetic fluctuations with good time and space resolution (of the order of few ion Larmor radii). Small-scale electromagnetic quasi-coherent instabilities are revealed during the helical states of the plasma. Their amplitude is correlated to the electron temperature gradient strength in the core. The comparison of experimental data with dedicated linear gyrokinetic simulations permits to identify such instabilities as microtearing modes. The relation between the observed time evolution of the spectral properties and the magnetic equilibrium is analyzed mainly in terms of the helical q profile. The possible effects on heat transport in RFP plasmas are also discussed. References [1] I. Predebon, F. Sattin, M. Veranda, D. Bonfiglio, and S. Cappello Phys. Rev. Lett. 105, 195001 (2010)

RFX-mod [Sonato et al., Fusion Eng. Des. 66, 161 (2003)] exploits its 192 active coils in both reversed-field pinch (RFP) and tokamak configurations with varying degrees of 3D shaping, providing also a test bed for validating stellarator codes and 3D nonlinear magnetohydrodynamic codes. This makes RFX-mod a unique and flexible facility for comparative studies on 3D shaping and control. The paper discusses how 3D fields allow access to RFP and tokamak advanced regimes. 3D fields are used to feedback control Single Helicity (SH) RFP equilibria with 1/7 helicity up to similar to 2 MA. They also allow accessing SH regimes with higher density (Greenwald fraction up to 0.5), presently inaccessible in spontaneous SH regimes. Feedback on the 2/1 resistive-wall mode in RFX-mod tokamak plasmas allows for safe operation at q(a) < 2, an almost unexplored promising regime. Forcing the 2/1 mode to saturate at finite but small level, a helical tokamak equilibrium with significant n=1 modulation is produced and a new way to tailor sawteeth is found. The effects of different levels of 3D shaping on momentum transport in both RFP and tokamak helical states are discussed.

Filamentary structures elongated in the magnetic field line direction have been detected in magnetized plasmas ranging from laboratory, including thermonuclear fusion devoted experiments, to astrophysical ones. A special attention is paid to the study of turbulent features characterizing edge plasmas of toroidal devices for magnetic plasma confinement, where this represents a hot topic due to the role played by coherent structures in contributing to the transport of particles and energy. Recently an increasing interest has been devoted also to the study of the field-aligned features of these filamentary plasma structures, including both their electrostatic and electromagnetic properties. New information is then provided beyond the standard cross-field characterization, and direct measurement of associated parallel current density, Jpar, and vorticity, ?par, is added. It is worth mentioning that a special relevance for fusion devoted experiments is ascribed to current density associated to ELMs phenomena, observed in the edge of magnetic confinement fusion devices. In this respect a strong experimental effort is in progress in order to provide accurate information on structure features and to gain insight on their dynamics and ultimately on their driving mechanisms. In particular a direct observation of current density filaments associated to the so called "blobs" or turbulent structures has been performed in the edge region of the RFX-mod Reversed Field Pinch (RFP) device, where drift kinetic Alfvén structures have been identified. Similar filaments have been observed also in the TORPEX experiment, simple magnetized toroidal plasma, where blobs are originated by ideal interchange waves. In this last case, for the first time the cross-field map of the parallel current density in the filaments has been revealed. Similar investigations were carried out in the edge region of the TJ-II stellarator experiment, where a range of plasma beta can be explored. Aim of this contribution is to present a comparison of electromagnetic properties of turbulent structures, exploiting the complementarity of four different magnetic configurations: the TORPEX device , characterized by open field lines, and the hotter fusion plasmas of the TJ-II stellarator and RFX-mod, which can be operated with both RFP and ohmic tokamak configurations and allows an active control of the edge magnetic topology. Thanks to an original diagnostic concept, direct measurements of both Jpar and ?par were performed inside the filament, in all the explored configurations. The inter-machine comparison revealed a clear dependence of the filament vorticity upon the local time-averaged ExB flow shear. Furthermore, the exercise covered a wide range of local beta showing that this parameter plays a fundamental role in the appearance of filament-like electromagnetic features.

In present fusion research a strong effort is devoted to the studies of non axisymmetric magnetic perturbations and consequent field ergodization on the external region of the plasma. On this topic interesting results can be drawn from the helical configuration observed in high-current regimes in Reversed Field Pinches (RFP) where the small edge helical ripple is sufficient to modulate the plasma wall interaction (PWI) and the plasma kinetic properties. This contribution presents the most recent experimental results and physical interpretation of the phenomena observed in the edge region of the RFX-mod RFP experiment. Experimental observations indicate that plasma pressure and floating potential are spatially modulated accordingly to the helical deformation. Helical flow is observed at the edge as a consequence of an ambipolar electricfield. Emphasis will be devoted to the determination of the actual phase relation between magnetic perturbation and velocity perturbation, and its dependence on plasma collisionality. Finally, the helical ripple is found to influence also turbulence properties at the edge.

Helical (stellarator-like) equilibria can occur in the core of nominally axisymmetric tokamak and RFP plasmas, including the "snake" in JET, planned hybrid-scenario plasmas in ITER, and the "single-helical-axis" (SHAx) state in RFX-mod. Here we report for the first time the emergence of the SHAx state in MST, and we report the first direct measurement of the internal magnetic field evolution associated with such a helical equilibrium. Both the probability of the SHAx state's emergence and its duration increase strongly with Ip inMST and RFX-mod, but the required Ip in MST is lower than in RFX-mod. However, due to differences in other plasmas parameters as well, the two devices share a common range of the dimensionless Lundquist number, thus better unifying the results. This state is still not entirely understood, but recent theoretical work analogizing the helical structure to a coherent turbulent vortex predicts that the structure's ability to sustain itself increases with Ip.

The RFX-mod fusion science program has made significant progress since the last 2010 IAEA Fusion Energy Conference. The activities focused on the goal of exploring the fusion potential of the RFP magnetic configuration and that of contributing to the solution of key science and technology problems in the roadmap to ITER. Active control of several plasma parameters has been a key tool in this program. New upgrades on the system for active control of MHD stability are under way and will be presented here. Unique in the portfolio of existing fusion devices, RFX-mod has been operated both as a RFP and as a tokamak. The latter operation has allowed the exploration of qedge

New edge diagnostics and detailed analysis of magnetic topology have significantly improved the comprehension of the processes developing at the boundary of a reversed-field pinch (RFP) plasma in RFX-mod (a = 0.46 m, R = 2 m). An upper critical density n C ≈ 0.4 n G (n G Greenwald density) is found to limit the operational space for the improved quasi-single helical (QSH) regime: magnetic topology reconstructions and diagnostic observations suggest that this limit is due to a helical plasma–wall interaction which determines toroidally and poloidally localized edge density accumulation and cooling. The experimental evidence is provided by a variety of diagnostics: the magnetic boundary as reconstructed from equilibrium codes reveals a helical deformation, which is well correlated with the modulation of edge pressure profile as reconstructed from the thermal helium beam diagnostic. Correlations with the helical deformation are also observed on the space- and time-resolved patterns of the floating potential measured at the wall, and with the edge plasma flow, obtained from different diagnostics. The relevance of these findings is that understanding the mechanisms that limit the operational space of QSH is decisive in achieving the goal of high-density stationary helical RFP equilibrium.

MST plasmas with a central 3D helical structure are now routinely achievable. As in RFX-mod, the stellarator-like structure arises in otherwise toroidally axisymmetric plasmas when the innermost-resonant m = 1 tearing mode grows to large amplitude and dominates the core-resonant-mode spectrum. The tearing mode spectrum in MST varies strongly with toroidal plasma current. Peaked spectra with a helical structure occur most reliably at high Ip (0.6 MA), while at low Ip (0.2 MA), the spectra are quite flat. This trend is like that in RFX-mod and may reflect a dependence on the Lundquist number. Preliminary MST data also show that manipulation of the inductive electric field has a significant impact, driving the dominant mode to large amplitude more robustly, and reducing the other modes. At high Ip, Te(0) $>$ 1 keV with a possible several-fold increase in the energy confinement time. Supported by USDOE.

IAEA Fusion Energy Conference 2010 Proceedings of the 23rd IAEA Fusion Energy Conference Daejeon, 11-16 October 2010 Organized by the International Atomic Energy Agency and hosted by the Government of the Republic of Korea IAEA-CN-180 (EXC/P4-10) Internal and Edge Electron Transport Barriers in the RFX-Mod Reversed Field Pinch M.E. Puiatti1), M. Valisa1), A. Alfier1), M. Agostini1), L. Apolloni1), F. Auriemma1), M. Baruzzo1), T. Bolzonella1), D. Bonfiglio1), F. Bonomo1), A. Canton1), S. Cappello1), L. Carraro1), R. Cavazzana1), S. Dal Bello1), G. De Masi1), D.F. Escande2), A. Fassina1), P. Franz1), E. Gazza1), M. Gobbin1), S. Guo1), P. Innocente1), R. Lorenzini1), G. Marchiori1), L. Marrelli1), P. Martin1), E. Martines1), S. Martini1), S. Menmuir1), B. Momo1), L. Novello1), R. Paccagnella1), P. Piovesan1), L. Piron1), I. Predebon1), A. Ruzzon1), F. Sattin1), A. Scaggion1), P. Scarin1), A. Soppelsa1), G. Spizzo1), S. Spagnolo1), M. Spolaore1), D. Terranova1), M. Veranda1), N. Vianello1), P. Zanca1), B. Zaniol1), L. Zanotto1), M. Zuin1) 1) Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Padova, Italy 2) Laboratoire PIIM, UMR 6633 CNRS-Aix Marseille Université, France Abstract. An interesting result of the self-organization processes in RFX-mod high current discharges is the development of strong electron transport barriers. An internal heat and particle transport barrier is formed when a bifurcation process changes the magnetic configuration into a helical equilibrium (SH) and chaos reduction follows, together with the formation of a null in the q shear. Turbulence analysis shows that the large electron temperature gradients are likely limited by the onset of micro-tearing modes. A new type of electron transport barrier with strong temperature gradients develops more externally (r/a = 0.8), independently on the presence of the helical equilibrium, accompanied by a 30% improvement of the global confinement time. Both types of barriers occur in high current low collisionality regimes. Analogies with Tokamak and Stellarators are discussed.

In RFX-mod high current experiments the plasma frequently reaches the Single Helical Axis (SHAx) state, in which the core electron temperature assumes a helical shape and significant gradients appear. The plasma magnetic topology is strongly helical in the core while it is almost axisymmetric at the edge, thanks to the active control of the edge radial field. The weak helical field produced by the plasma profoundly affects the shape of the equilibrium going from 2D to 3D, therefore three-dimensional tools are being developed for the description of these states. On one hand the SHEq code, based on a perturbative approach, is used to determine the magnetic field topology. On the other hand, the VMEC code has been modified for the helical RFP, in order to describe the SHAx states by using tools developed by the Stellarator community. The effect of three-dimensional fields on transport is also being actively investigated. The magnetic shear is found to be correlated with regions with reduced transport: an investigation on the effect of 3D fields on transport mechanisms underlying such barriers is being performed by adopting several approaches.

With the exploration of the MA plasma current regime in up to 0.5 s long discharges, RFX-mod has opened new and promising perspectives for the Reversed Field Pinch (RFP). A big leap with respect to previous knowledge and expectations on RFP physics and performance has been made by RFX-mod since the last 2006 IAEA Fusion Energy Conference. We present results, which are relevant for the understanding of the RFP physics and confinement performance, and contribute to the solution of issues for the optimization of ITER construction and operation. RFX-mod is a large ohmically heated RFP (R = 2 m, a = 0.457 m, volume 10 m3), equipped with an advanced system for feedback control of MHD instabilities, based on 192 independently driven coils covering the whole plasma boundary. An axisymmetric magnetic boundary is produced, with differential rotation of tearing modes and full stabilization of multiple RWM. The operation above 1 MA (up to 1.6 MA reported at this conference) has revealed a new self-organised helical equilibrium (the Single Helical Axis - SHAx - state), which is the preferred state at high current. This regime is characterized by strong core electron transport barriers, with electron temperature gradients comparable to those achieved in tokamaks, and by a factor four improvement in confinement time with respect to the standard RFP. The electron temperature shows peak values in the 1 keV range, linearly increasing with plasma current with no degradation of beta. The RFP dominated by magnetic chaos belongs to the past, and the new findings open an exciting and clear path, which deserved to be explored. The achievements in the field of MHD stability real-time control have been of high quality. Progresses in control of tearing modes and RWM have been reported. Besides providing an improved magnetic boundary for the high current operation, the feedback experiments address general issues like multi-mode control, tools for mode unlocking and for forcing mode rotation, implementation of advanced control theory, development of a plant model including features of the plasma, wall, sensors, actuators, field error environment, noise environment and controller dynamics, incorporation of 3-d effects due to a non-axisymmetric wall, benchmarking of numerical stability codes also used for ITER. All these results give strong confidence in the RFX-mod future programme.

A source for the production of low-power plasmas at atmospheric pressure, to be used for the nondamaging sterilization of living tissues, is presented. The source, powered by radiofrequency and working with a helium flow, has a specific configuration, studied to prevent the formation of electric arcs dangerous to living matter. It is capable of killing different types of bacteria with a decimal reduction time of 1?2?min; on the contrary, human cells such as conjunctival fibroblasts were found to be almost unharmed by the plasma. A high concentration of OH radicals, likely to be the origin of the sterilizing effect, is detected through their UV emission lines. The effect of the UV and the OH radicals on the fibroblasts was analysed and no significant effects were detected.