Edge localized modes (ELMs), that are present in most tokamak H-(high confinement) modes, can cause significant damage to plasma facing components in fusion reactors. Controlling ELMs is considered necessary and hence it is vital to understand the underlying physics. The stability of ELMs is typically expressed in terms of the pressure gradient del p in the edge and the edge current density j(phi) Both del p and j(phi) are usually derived from profiles fitted to the measured edge density and temperature profiles, where for the calculation of j(phi) neoclassical theory is used. This paper presents direct measurements of the magnetic pitch angle gamma(m) evolution in the edge and the derived j(phi). These provide a method to validate the j(phi) as derived with neoclassical theory and they open up the possibility to find a complete, self-consistent set of edge profiles, that fit density, temperature and gamma(m) measurements, hence allowing for a more accurate stability analysis.

VL - 54 SN - 0741-3335 U1 -FP

U2 -CPP-HT

U5 - 87dc9949c54cfd4cccb26830a22a998a 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 - The physics of sawtooth stabilization JF - Plasma Physics and Controlled Fusion Y1 - 2007 A1 - Chapman, I.T. A1 - Pinches, S. D. A1 - Graves, J. P. A1 - Akers, R. J. A1 - Appel, L. C. A1 - Budny, R. V. A1 - Coda, S. A1 - Conway, N. J. A1 - De Bock, M. A1 - Eriksson, L.-G. A1 - Hastie, R. J. A1 - Hender, T. C. A1 - Huysmans, G. T. A. A1 - Johnson, T. A1 - Koslowski, H. R. A1 - Kramer-Flecken, A. A1 - Lennholm, M. A1 - Liang, Y. A1 - Saarelma, S. A1 - Sharapov, S. E. A1 - Voitsekhovitch, I. A1 - the MAST and TEXTOR Teams and JET EFDA Contributors, VL - 49 U1 - Fusion Physics U2 - Instrumentation development U5 - 0a2c50525dc1de60da5e572c4c965ace ER - TY - JOUR T1 - Stability at high performance in the MAST spherical tokamak JF - Nuclear Fusion Y1 - 2004 A1 - Buttery, R. J. A1 - Akers, R. A1 - Arends, E. A1 - Conway, N. J. A1 - Counsell, G. F. A1 - Cunningham, G. A1 - Gimblett, C. G. A1 - Gryaznevich, M. A1 - Hastie, R. J. A1 - Hole, M. J. A1 - Lehane, I. A1 - Martin, R. A1 - Patel, A. A1 - Pinfold, T. A1 - Sauter, O. A1 - Taylor, D. A1 - Turri, G. A1 - Valovic, M. A1 - Walsh, M. J. A1 - Wilson, H. R. VL - 44 SN - 0029-5515 UR -