Recent experiments with the ITER-like wall have demonstrated that changes in divertor strike point position are correlated with strong modification of the global energy confinement. The impact on energy confinement is observable both on the pedestal confinement and core normalised gradients. The corner configuration shows an increased core density gradient length and ion pressure indicating a better ion confinement. The study of neutral re-circulation indicates the neutral pressure in the main chamber varies inversely with the energy confinement and a correlation between the pedestal total pressure and the neutral pressure in the main chamber can be established. It does not appear that charge exchange losses nor momentum losses could explain this effect, but it may be that changes in edge electric potential are playing a role at the plasma edge. This study emphasizes the importance of the scrape-off layer (SOL) conditions on the pedestal and core confinement.

VL - 57 UR - http://www.euro-fusionscipub.org/wp-content/uploads/eurofusion/WPJET1PR16_14476_submitted.pdf IS - 8 U1 -FP

U2 -TP

U5 - 1d310d9705dcacde013663de3e5e6cf7 ER - TY - JOUR T1 - Mitigation of divertor heat loads by strike point sweeping in high power JET discharges JF - Physica Scripta Y1 - 2017 A1 - Silburn, S. A. A1 - Matthews, G. F. A1 - Challis, C. D. A1 - Frigione, D. A1 - Graves, J. P. A1 - Mantsinen, M. J. A1 - Belonohy, E. A1 - Hobirk, J. A1 - Iglesias, D. A1 - Keeling, D. L. A1 - King, D. A1 - Kirov, K. A1 - Lennholm, M. A1 - Lomas, P. J. A1 - Moradi, S. A1 - Sips, A. C. C. A1 - Tsalas, M. A1 - JET Contributors AB - Deliberate periodic movement (sweeping) of the high heat flux divertor strike lines in tokamak plasmas can be used to manage the heat fluxes experienced by exhaust handling plasma facing components, by spreading the heat loads over a larger surface area. Sweeping has recently been adopted as a routine part of the main high performance plasma configurations used on JET, and has enabled pulses with 30 MW plasma heating power and 10 MW radiation to run for 5 s without overheating the divertor tiles. We present analysis of the effectiveness of sweeping for divertor temperature control on JET, using infrared camera data and comparison with a simple 2D heat diffusion model. Around 50% reduction in tile temperature rise is obtained with 5.4 cm sweeping compared to the un-swept case, and the temperature reduction is found to scale slower than linearly with sweeping amplitude in both experiments and modelling. Compatibility of sweeping with high fusion performance is demonstrated, and effects of sweeping on the edge-localised mode behaviour of the plasma are reported and discussed. The prospects of using sweeping in future JET experiments with up to 40 MW heating power are investigated using a model validated against existing experimental data. VL - 2017 IS - T170 U1 - FP U2 - TP U5 - a7ec5c94dd16aa2a77e5af5e73d311a6 ER - TY - JOUR T1 - Improved confinement in JET high β plasmas with an ITER-like wall JF - Nuclear Fusion Y1 - 2015 A1 - Challis, C. D. A1 - J. Garcia A1 - Beurskens, M. A1 - Buratti, P. A1 - Delabie, E. A1 - Drewelow, P. A1 - Frassinetti, L. A1 - Giroud, C. A1 - Hawkes, N. A1 - Hobirk, J. A1 - Joffrin, E. A1 - Keeling, D. A1 - D. B. King A1 - Maggi, C. F. A1 - J. Mailloux A1 - Marchetto, C. A1 - McDonald, D. A1 - Nunes, I. A1 - Pucella, G. A1 - Saarelma, S. A1 - J. Simpson A1 - JET Contributors VL - 55 UR - www.arxiv.org/abs/1501.03929 IS - 5 U1 - FP U2 - PDG U5 - a1d802df46a7b0343697703f59d35544 ER - TY - JOUR T1 - Development of advanced inductive scenarios for ITER JF - Nuclear Fusion Y1 - 2014 A1 - Luce, T. C. A1 - Challis, C. D. A1 - Ide, S. A1 - Joffrin, E. A1 - Kamada, Y. A1 - Polizer, P. A. A1 - Schweinzer, J. A1 - Sips, A.C.C. A1 - Stober, J. A1 - Giruzzi, G. A1 - Kessel, C. E. A1 - Murakami, M. A1 - Na, Y.-S. A1 - Park, J. M. A1 - Polevoi, A. R. A1 - Budny, R. V. A1 - Citrin, J. A1 - J. Garcia A1 - Hayashi, N. A1 - Hobirk, J. A1 - Hudson, B. F. A1 - Imbeaux, F. A1 - Isayama, A. A1 - McDonald, D. C. A1 - Nakano, T. A1 - Oyama, N. A1 - Parail, V.V. A1 - Petrie, T. W. A1 - Petty, C. C. A1 - Suzuki, T. A1 - Wade, M. R. AB -Since its inception in 2002, the International Tokamak Physics Activity topical group on Integrated Operational Scenarios (IOS) has coordinated experimental and modelling activity on the development of advanced inductive scenarios for applications in the ITER tokamak. The physics basis and the prospects for applications in ITER have been advanced significantly during that time, especially with respect to experimental results. The principal findings of this research activity are as follows. Inductive scenarios capable of higher normalized pressure (beta(N)>= 2.4) than the ITER baseline scenario (beta(N) = 1.8) with normalized confinement at or above the standard H-mode scaling are well established under stationary conditions on the four largest diverted tokamaks (AUG, DIII-D, JET, JT-60U), demonstrated in a database of more than 500 plasmas from these tokamaks analysed here. The parameter range where high performance is achieved is broad in q(95) and density normalized to the empirical density limit. MHD modes can play a key role in reaching stationary high performance, but also define the limits to achieved stability and confinement. Projection of performance in ITER from existing experiments uses empirical scalings and theory-based modelling. The status of the experimental validation of both approaches is summarized here. The database shows significant variation in the energy confinement normalized to standard H-mode confinement scalings, indicating the possible influence of additional physics variables absent from the scalings. Tests using the available information on rotation and the ratio of the electron and ion temperatures indicate neither of these variables in isolation can explain the variation in normalized confinement observed. Trends in the normalized confinement with the two dimensionless parameters that vary most from present-day experiments to ITER, gyroradius and collision frequency, are significant. Regression analysis on the multi-tokamak database has been performed, but it appears that the database is not conditioned sufficiently well to yield a new scaling for this type of plasma. Coordinated experiments on size scaling using the dimensionless parameter scaling approach find a weaker scaling with normalized gyroradius than the standard H-mode scaling. Preliminary studies on scaling with collision frequency show a favourable scaling stronger than the standard H-mode scaling. Coordinated modelling activity has resulted in successful benchmarking of modelling codes in the ITER regime. Validation of transport models using these codes on present-day experiments is in progress, but no single model has been shown to capture the variations seen in the experiments. However, projection to ITER using these models is in general agreement with the favourable projections found with the empirical scalings.

VL - 54 SN - 0029-5515 IS - 1 U1 -FP

U2 -CPP-HT

U5 - bd8e6e10ad1da6f54b5c768c2cad759e ER - TY - JOUR T1 - First scenario development with the JET new ITER-like wall JF - Nuclear Fusion Y1 - 2014 A1 - Joffrin, E. A1 - Baruzzo, M. A1 - Beurskens, M. A1 - Bourdelle, C. A1 - Brezinsek, S. A1 - Bucalossi, J. A1 - Buratti, P. A1 - Calabro, G. A1 - Challis, C. D. A1 - Clever, M. A1 - Coenen, J. W. A1 - Delabie, E. A1 - Dux, R. A1 - Lomas, P. A1 - de la Luna, E. A1 - P. de Vries A1 - Flanagan, J. A1 - Frassinetti, L. A1 - Frigione, D. A1 - Giroud, C. A1 - Groth, M. A1 - Hawkes, N. C. A1 - Hobirk, J. A1 - Lehnen, M. A1 - Maddison, G. A1 - J. Mailloux A1 - Maggi, C. F. A1 - Matthews, G. A1 - Mayoral, M. A1 - Meigs, A. A1 - Neu, R. A1 - Nunes, I. A1 - T. Puetterich A1 - Rimini, F. A1 - Sertoli, M. A1 - Sieglin, B. A1 - Sips, A.C.C. A1 - G. J. van Rooij A1 - Voitsekhovitch, I. A1 - JET-EFDA Contributors AB - In the recent JET experimental campaigns with the new ITER-like wall (JET-ILW), major progress has been achieved in the characterization and operation of the H-mode regime in metallic environments: (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 H-modes with beta(N) similar to 1.4 have been achieved in low and high triangularity ITER-like 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 a large amount of gas (above 10(22) Ds(-1)) to control core radiation; (iii) in contrast, the hybrid H-mode scenario has reached an H factor of 1.2-1.3 at beta(N) of 3 for 2-3 s; and, (iv) in comparison to carbon equivalent discharges, total radiation is similar but the edge radiation is lower and Z(eff) of the order of 1.3-1.4. Strong core radiation peaking is observed in H-mode discharges at a low gas fuelling rate (i. e. below 0.5 x 10(22) Ds(-1)) and low ELM frequency (typically less than 10 Hz), even when the tungsten influx from the diverter is constant. High-Z impurity transport from the plasma edge to the core appears to be the dominant factor to explain these observations. This paper reviews the major physics and operational achievements and challenges that an ITER-like wall configuration has to face to produce stable plasma scenarios with maximized performance. VL - 54 SN - 0029-5515 UR - http://www.iop.org/Jet/article?EFDP13011&EFDP13017 U1 - FP U2 - PDG U5 - 0bbcf7872d4f177a71b6808802db9454 ER - TY - JOUR T1 - Energetic particle instabilities in fusion plasmas JF - Nuclear Fusion Y1 - 2013 A1 - Sharapov, S. E. A1 - Alper, B. A1 - Berk, H. L. A1 - Borba, D. N. A1 - Breizman, B. N. A1 - Challis, C. D. A1 - Classen, I.G.J. A1 - Edlund, E. M. A1 - Eriksson, J. A1 - Fasoli, A. A1 - Fredrickson, E. D. A1 - Fu, G. Y. A1 - M. García-Muñoz A1 - Gassner, T. A1 - Ghantous, K. A1 - Goloborodko, V. A1 - Gorelenkov, N. N. A1 - Gryaznevich, M. P. A1 - Hacquin, S. A1 - Heidbrink, W. W. A1 - Hellesen, C. A1 - Kiptily, V. G. A1 - Kramer, G. J. A1 - Lauber, P. A1 - Lilley, M. K. A1 - Lisak, M. A1 - Nabais, F. A1 - Nazikian, R. A1 - Nyqvist, R. A1 - Osakabe, M. A1 - C. Perez von Thun A1 - Pinches, S. D. A1 - Podesta, M. A1 - Porkolab, M. A1 - Shinohara, K. A1 - Schoepf, K. A1 - Todo, Y. A1 - Toi, K. A1 - VanZeeland, M. A. A1 - Voitsekhovich, I. A1 - White, R. B. A1 - Yavorskij, V. A1 - ITPA EP TG Contributors A1 - JET-EFDA Contributors AB - Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge. VL - 53 UR - http://www.ccfe.ac.uk/assets/Documents/NFvol53p104022.pdf U1 - FP U2 - PDG U5 - 6ae2288304ffc398124ca958dfb8a3ef ER - TY - JOUR T1 - Overview of physics results from MAST towards ITER/DEMO and the MAST Upgrade JF - Nuclear Fusion Y1 - 2013 A1 - Meyer, H. A1 - Abel, I. G. A1 - Akers, R. J. A1 - Allan, A. A1 - Allan, S. Y. A1 - Appel, L. C. A1 - Asunta, O. A1 - Barnes, M. A1 - Barratt, N. C. A1 - N. Ben Ayed A1 - Bradley, J. W. A1 - Canik, J. A1 - Cahyna, P. A1 - Cecconello, M. A1 - Challis, C. D. A1 - Chapman, I.T. A1 - Ciric, D. A1 - Colyer, G. A1 - Conway, N. J. A1 - Cox, M. A1 - Crowley, B. J. A1 - Cowley, S. C. A1 - Cunningham, G. A1 - Danilov, A. A1 - Darke, A. A1 - de Bock, M. F. M. A1 - De Temmerman, G. A1 - Dendy, R. O. A1 - Denner, P. A1 - Dickinson, D. A1 - Dnestrovskij, A. Y. A1 - Dnestrovsky, Y. A1 - Driscoll, M. D. A1 - Dudson, B. A1 - Dunai, D. A1 - Dunstan, M. A1 - Dura, P. A1 - Elmore, S. A1 - Field, A. R. A1 - Fishpool, G. A1 - Freethy, S. A1 - Fundamenski, W. A1 - Garzotti, L. A1 - Ghim, Y. C. A1 - Gibson, K. J. A1 - Gryaznevich, M. P. A1 - Harrison, J. A1 - E. Havlíčková A1 - Hawkes, N. C. A1 - Heidbrink, W. W. A1 - Hender, T. C. A1 - Highcock, E. A1 - Higgins, D. A1 - Hill, P. A1 - Hnat, B. A1 - Hole, M. J. A1 - J. Horáček A1 - Howell, D. F. A1 - Imada, K. A1 - Jones, O. A1 - Kaveeva, E. A1 - Keeling, D. A1 - Kirk, A. A1 - M. Kočan A1 - Lake, R. J. A1 - Lehnen, M. A1 - Leggate, H. J. A1 - Liang, Y. A1 - Lilley, M. K. A1 - Lisgo, S. W. A1 - Liu, Y. Q. A1 - Lloyd, B. A1 - G. P. Maddison A1 - J. Mailloux A1 - Martin, R. A1 - McArdle, G. J. A1 - McClements, K. G. A1 - McMillan, B. A1 - Michael, C. A1 - Militello, F. A1 - Molchanov, P. A1 - Mordijck, S. A1 - Morgan, T. A1 - Morris, A. W. A1 - Muir, D. G. A1 - Nardon, E. A1 - Naulin, V. A1 - Naylor, G. A1 - Nielsen, A. H. A1 - O'Brien, M. R. A1 - O'Gorman, T. A1 - Pamela, S. A1 - Parra, F. I. A1 - Patel, A. A1 - Pinches, S. D. A1 - Price, M. N. A1 - Roach, C. M. A1 - Robinson, J. R. A1 - Romanelli, M. A1 - Rozhansky, V. A1 - Saarelma, S. A1 - Sangaroon, S. A1 - Saveliev, A. A1 - Scannell, R. A1 - Seidl, J. A1 - Sharapov, S. E. A1 - Schekochihin, A. A. A1 - Shevchenko, V. A1 - Shibaev, S. A1 - Stork, D. A1 - Storrs, J. A1 - Sykes, A. A1 - Tallents, G. J. A1 - Tamain, P. A1 - Taylor, D. A1 - Temple, D. A1 - Thomas-Davies, N. A1 - Thornton, A. A1 - Turnyanskiy, M. R. A1 - M. Valovič A1 - Vann, R. G. L. A1 - Verwichte, E. A1 - Voskoboynikov, P. A1 - Voss, G. A1 - Warder, S. E. V. A1 - Wilson, H. R. A1 - Wodniak, I. A1 - Zoletnik, S. A1 - Zagorski, R. A1 - MAST Team A1 - NBI Team AB - New diagnostic, modelling and plant capability on the Mega Ampère Spherical Tokamak (MAST) have delivered important results in key areas for ITER/DEMO and the upcoming MAST Upgrade, a step towards future ST devices on the path to fusion currently under procurement. Micro-stability analysis of the pedestal highlights the potential roles of micro-tearing modes and kinetic ballooning modes for the pedestal formation. Mitigation of edge localized modes (ELM) using resonant magnetic perturbation has been demonstrated for toroidal mode numbers n = 3, 4, 6 with an ELM frequency increase by up to a factor of 9, compatible with pellet fuelling. The peak heat flux of mitigated and natural ELMs follows the same linear trend with ELM energy loss and the first ELM-resolved T i measurements in the divertor region are shown. Measurements of flow shear and turbulence dynamics during L–H transitions show filaments erupting from the plasma edge whilst the full flow shear is still present. Off-axis neutral beam injection helps to strongly reduce the redistribution of fast-ions due to fishbone modes when compared to on-axis injection. Low- k ion-scale turbulence has been measured in L-mode and compared to global gyro-kinetic simulations. A statistical analysis of principal turbulence time scales shows them to be of comparable magnitude and reasonably correlated with turbulence decorrelation time. T e inside the island of a neoclassical tearing mode allow the analysis of the island evolution without assuming specific models for the heat flux. Other results include the discrepancy of the current profile evolution during the current ramp-up with solutions of the poloidal field diffusion equation, studies of the anomalous Doppler resonance compressional Alfvén eigenmodes, disruption mitigation studies and modelling of the new divertor design for MAST Upgrade. The novel 3D electron Bernstein synthetic imaging shows promising first data sensitive to the edge current profile and flows. VL - 53 UR - http://stacks.iop.org/0029-5515/53/i=10/a=104008 U1 - PSI U2 - PSI-E U5 - fee6f536ea06c1003255446f71a039bd ER - TY - JOUR T1 - Improved confinement in JET hybrid discharges JF - Plasma Physics and Controlled Fusion Y1 - 2012 A1 - Hobirk, J. A1 - Imbeaux, F. A1 - Crisanti, F. A1 - Buratti, P. A1 - Challis, C. D. A1 - Joffrin, E. A1 - Alper, B. A1 - Andrew, Y. A1 - Beaumont, P. A1 - Beurskens, M. A1 - Boboc, A. A1 - Botrugno, A. A1 - Brix, M. A1 - Calabro, G. A1 - Coffey, I. A1 - Conroy, S. A1 - Ford, O. A1 - Frigione, D. A1 - J. Garcia A1 - Giroud, C. A1 - Hawkes, N. C. A1 - Howell, D. A1 - Jenkins, I. A1 - Keeling, D. A1 - Kempenaars, M. A1 - Leggate, H. A1 - Lotte, P. A1 - de la Luna, E. A1 - G. P. Maddison A1 - Mantica, P. A1 - Mazzotta, C. A1 - McDonald, D. C. A1 - Meigs, A. A1 - Nunes, I. A1 - Rachlew, E. A1 - Rimini, F. A1 - Schneider, M. A1 - Sips, A.C.C. A1 - Stober, J. K. A1 - Studholme, W. A1 - Tala, T. A1 - Tsalas, M. A1 - Voitsekhovitch, I. A1 - de Vries, P. C. KW - ASDEX KW - DIII-D TOKAMAK KW - HEAT-TRANSPORT KW - IMPROVED H-MODE KW - INTERNAL TRANSPORT BARRIER KW - ITER KW - PERFORMANCE KW - PLASMAS KW - SCENARIO KW - UPGRADE AB - A new technique has been developed to produce plasmas with improved confinement relative to the H-98,H-y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H-98,H-y2 = 1.35) and good stability (beta(N) approximate to 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H-98,H-y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase. VL - 54 SN - 0741-3335 UR - http://www.iop.org/Jet/article?EFDP10061&EFDP10065 IS - 9 U1 - FP U2 - PDG U5 - c6de3db62ee755182e9963d63cb93ce8 ER - TY - JOUR T1 - Large ELM-like events triggered by core MHD in JET advanced tokamak plasmas: impact on plasmas profiles, plasma-facing components and heating systems JF - Nuclear Fusion Y1 - 2012 A1 - Baranov, Y. F. A1 - Challis, C. D. A1 - Ongena, J. A1 - Alper, B. A1 - Arnoux, G. A1 - Buratti, P. A1 - Gerbaud, T. A1 - Keeling, D. A1 - Kiptily, V. A1 - J. Mailloux A1 - Mayoral, M. L. A1 - Monakhov, I. A1 - Parail, V. A1 - Sergienko, G. A1 - Sharapov, S. AB -Large and infrequent collapse events have been observed in high β N advanced tokamak (AT) plasmas in JET. Although they have features similar to large ELMs, they were triggered by core MHD. They caused a considerable loss of the plasma thermal and fast particle energy ( 10% of the total stored energy), but the heat load in the divertor due to these collapse events was small as a fraction of the plasma energy loss compared with regular type-I ELMs. Instead, significant heating of the main chamber wall was observed. A large, toroidally asymmetric, increase in the neutral gas pressure outside the plasma was observed after such events, which caused arcs in the lower hybrid (LH) and ion cyclotron (IC) heating systems and increased reionization in the neutral beam (NB) injectors. The collapses resulted in a reduction in the electron and ion temperatures and toroidal rotation of the whole plasma, a rise in Z eff ; and a sufficiently large increase in the peripheral electron density to completely black-out the ECE emission from the plasma core. These features have been modelled to gain an understanding of the plasma behaviour associated with these collapse events and the implication for the operation of AT plasma scenarios with high additional heating power will be discussed.

VL - 52 UR - http://www.euro-fusionscipub.org/wp-content/uploads/2014/11/EFDP10055.pdf IS - 2 U1 -FP

U2 -PDG

U5 - c376153b3a1ad9595ea8043c3eb4bc86 ER - TY - JOUR T1 - Overview of physics results from MAST JF - Nuclear Fusion Y1 - 2011 A1 - Lloyd, B. A1 - Akers, R. J. A1 - Alladio, F. A1 - Allan, S. A1 - Appel, L. C. A1 - Barnes, M. A1 - Barratt, N. C. A1 - N. Ben Ayed A1 - Breizman, B. N. A1 - Cecconello, M. A1 - Challis, C. D. A1 - Chapman, I.T. A1 - Ciric, D. A1 - Colyer, G. A1 - Connor, J. W. A1 - Conway, N. J. A1 - Cox, M. A1 - Cowley, S. C. A1 - Cunningham, G. A1 - Darke, A. A1 - De Bock, M. A1 - Delchambre, E. A1 - De Temmerman, G. A1 - Dendy, R. O. A1 - Denner, P. A1 - Driscoll, M. D. A1 - Dudson, B. A1 - Dunai, D. A1 - Dunstan, M. A1 - Elmore, S. A1 - Field, A. R. A1 - Fishpool, G. A1 - Freethy, S. A1 - Garzotti, L. A1 - Gibson, K. J. A1 - Gryaznevich, M. P. A1 - Guttenfelder, W. A1 - Harrison, J. A1 - Hastie, R. J. A1 - Hawkes, N. C. A1 - Hender, T. C. A1 - Hnat, B. A1 - Howell, D. F. A1 - Hua, M. D. A1 - Hubbard, A. A1 - Huysmans, G. A1 - Keeling, D. A1 - Kim, Y. C. A1 - Kirk, A. A1 - Liang, Y. A1 - Lilley, M. K. A1 - Lisak, M. A1 - Lisgo, S. A1 - Liu, Y. Q. A1 - G. P. Maddison A1 - Maingi, R. A1 - Manhood, S. J. A1 - Martin, R. A1 - McArdle, G. J. A1 - McCone, J. A1 - Meyer, H. A1 - Michael, C. A1 - Mordijck, S. A1 - Morgan, T. A1 - Morris, A. W. A1 - Muir, D. G. A1 - Nardon, E. A1 - Naylor, G. A1 - O'Brien, M. R. A1 - O'Gorman, T. A1 - Palenik, J. A1 - Patel, A. A1 - Pinches, S. D. A1 - Price, M. N. A1 - Roach, C. M. A1 - Rozhansky, V. A1 - Saarelma, S. A1 - Sabbagh, S. A. A1 - Saveliev, A. A1 - Scannell, R. A1 - Sharapov, S. E. A1 - Shevchenko, V. A1 - Shibaev, S. A1 - Stork, D. A1 - Storrs, J. A1 - Suttrop, W. A1 - Sykes, A. A1 - Tamain, P. A1 - Taylor, D. A1 - Temple, D. A1 - Thomas-Davies, N. A1 - Thornton, A. A1 - Turnyanskiy, M. R. A1 - Valovic, M. A1 - Vann, R. G. L. A1 - Voss, G. A1 - Walsh, M. J. A1 - Warder, S. E. V. A1 - Wilson, H. R. A1 - Windridge, M. A1 - Wisse, M. A1 - Zoletnik, S. KW - MODEL KW - TRANSPORT AB -Major developments on the Mega Amp Spherical Tokamak (MAST) have enabled important advances in support of ITER and the physics basis of a spherical tokamak (ST) based component test facility (CTF), as well as providing new insight into underlying tokamak physics. For example, L-H transition studies benefit from high spatial and temporal resolution measurements of pedestal profile evolution (temperature, density and radial electric field) and in support of pedestal stability studies the edge current density profile has been inferred from motional Stark effect measurements. The influence of the q-profile and E x B flow shear on transport has been studied in MAST and equilibrium flow shear has been included in gyro-kinetic codes, improving comparisons with the experimental data. H-modes exhibit a weaker q and stronger collisionality dependence of heat diffusivity than implied by IPB98(gamma, 2) scaling, which may have important implications for the design of an ST-based CTF. ELM mitigation, an important issue for ITER, has been demonstrated by applying resonant magnetic perturbations (RMPs) using both internal and external coils, but full stabilization of type-I ELMs has not been observed. Modelling shows the importance of including the plasma response to the RMP fields. MAST plasmas with q > 1 and weak central magnetic shear regularly exhibit a long-lived saturated ideal internal mode. Measured plasma braking in the presence of this mode compares well with neo-classical toroidal viscosity theory. In support of basic physics understanding, high resolution Thomson scattering measurements are providing new insight into sawtooth crash dynamics and neo-classical tearing mode critical island widths. Retarding field analyser measurements show elevated ion temperatures in the scrape-off layer of L-mode plasmas and, in the presence of type-I ELMs, ions with energy greater than 500 eV are detected 20 cm outside the separatrix. Disruption mitigation by massive gas injection has reduced divertor heat loads by up to 70%.

VL - 51 SN - 0029-5515 IS - 9 N1 - ISI Document Delivery No.: 818DPTimes Cited: 0Cited Reference Count: 60SI U1 -PSI

U2 -PSI-E

U5 - 9e9434147fddee9a0003e22469980e60 ER - TY - JOUR T1 - Pellet injection and high density ITB formation in JET advanced tokamak plasmas JF - Nuclear Fusion Y1 - 2007 A1 - Frigione, D. A1 - Garzotti, L. A1 - Challis, C. D. A1 - de M. Baar A1 - P. de Vries A1 - Brix, M. A1 - Garbet, X. A1 - Hawkes, N. A1 - Thyagaraja, A. A1 - Zabeo, L. VL - 47 SN - 0029-5515 UR -