Core barrier formation near integer q surfaces in DIII-D

被引:73
作者
Austin, M. E. [1 ]
Burrell, K. H.
Gentle, K. W.
Gohil, P.
Greenfield, C. M.
Groebner, R. J.
Heidbrink, W. W.
Luo, Y.
Kinsey, J. E.
Makowski, M. A.
McKee, G. R.
Nazikian, R.
Petty, C. C.
Prater, R.
Rhodes, T. L.
Shafer, M. W.
Van Zeeland, M. A.
机构
[1] Univ Texas, Austin, TX 78712 USA
[2] Gen Atom Co, San Diego, CA 92186 USA
[3] Univ Calif Irvine, Irvine, CA 92612 USA
[4] Lehigh Univ, Bethlehem, PA 18015 USA
[5] Lawrence Livermore Natl Lab, Livermore, CA 94550 USA
[6] Univ Wisconsin, Madison, WI 53706 USA
[7] Princeton Plasma Phys Lab, Princeton, NJ 08540 USA
[8] Calif State Univ Los Angeles, Los Angeles, CA 90032 USA
[9] Oak Ridge Inst Sci Educ, Oak Ridge, TN 37831 USA
关键词
D O I
10.1063/1.2245579
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
Recent DIII-D experiments have significantly improved the understanding of internal transport barriers (ITBs) that are triggered close to the time when an integer value of the minimum in q is crossed. While this phenomenon has been observed on many tokamaks, the extensive transport and fluctuation diagnostics on DIII-D have permitted a detailed study of the generation mechanisms of q-triggered ITBs as pertaining to turbulence suppression dynamics, shear flows, and energetic particle modes. In these discharges, the evolution of the q profile is measured using motional Stark effect polarimetry and the integer q(min) crossings are further pinpointed in time by the observation of Alfven cascades. High time resolution measurements of the ion and electron temperatures and the toroidal rotation show that the start of improved confinement is simultaneous in all three channels, and that this event precedes the traversal of integer q(min) by 5-20 ms. There is no significant low-frequency magnetohydrodynamic activity prior to or just after the crossing of the integer q(min) and hence magnetic reconnection is determined not to be the precipitant of the confinement change. Instead, results from the GYRO code point to the effects of zonal flows near low order rational q values as playing a role in ITB triggering. A reduction in local turbulent fluctuations is observed at the start of the temperature rise and, concurrently, an increase in turbulence poloidal flow velocity and flow shear is measured with the beam emission spectroscopy diagnostic. For the case of a transition to an enduring internal barrier the fluctuation level remains at a reduced amplitude. The timing and nature of the temperature, rotation, and fluctuation changes leading to internal barriers suggests transport improvement due to increased shear flow arising from the zonal flow structures. (c) 2006 American Institute of Physics.
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页数:8
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共 28 条
[11]   Enhanced sensitivity beam emission spectroscopy system for nonlinear turbulence measurements [J].
Gupta, DK ;
Fonck, RJ ;
McKee, GR ;
Schlossberg, DJ ;
Shafer, MW .
REVIEW OF SCIENTIFIC INSTRUMENTS, 2004, 75 (10) :3493-3495
[12]   Hydrogenic fast-ion diagnostic using Balmer-alpha light [J].
Heidbrink, WW ;
Burrell, KH ;
Luo, Y ;
Pablant, NA ;
Ruskov, E .
PLASMA PHYSICS AND CONTROLLED FUSION, 2004, 46 (12) :1855-1875
[13]   Internal transport barrier triggering by rational magnetic flux surfaces in tokamaks [J].
Joffrin, E ;
Challis, CD ;
Conway, GD ;
Garbet, X ;
Gude, A ;
Günter, S ;
Hawkes, NC ;
Hender, TC ;
Howell, DF ;
Huysmans, GTA ;
Lazzaro, E ;
Maget, P ;
Marachek, M ;
Peeters, AG ;
Pinches, SD ;
Sharapov, SE .
NUCLEAR FUSION, 2003, 43 (10) :1167-1174
[14]   Triggering of internal transport barrier in JET [J].
Joffrin, E ;
Gorini, G ;
Challis, CD ;
Hawkes, NC ;
Hender, TC ;
Howell, DF ;
Maget, P ;
Mantica, P ;
Mazon, D ;
Sharapov, SE ;
Tresset, G .
PLASMA PHYSICS AND CONTROLLED FUSION, 2002, 44 (08) :1739-1752
[15]   Nonlinear gyrokinetic turbulence simulations of ExB shear quenching of transport -: art. no. 062302 [J].
Kinsey, JE ;
Waltz, RE ;
Candy, J .
PHYSICS OF PLASMAS, 2005, 12 (06) :1-9
[16]   INTERNAL TRANSPORT BARRIER ON Q=3 SURFACE AND POLOIDAL PLASMA SPIN-UP IN JT-60U HIGH-BETA(P) DISCHARGES [J].
KOIDE, Y ;
KIKUCHI, M ;
MORI, M ;
TSUJI, S ;
ISHIDA, S ;
ASAKURA, N ;
KAMADA, Y ;
NISHITANI, T ;
KAWANO, Y ;
HATAE, T ;
FUJITA, T ;
FUKUDA, T ;
SAKASAI, A ;
KONDOH, T ;
YOSHINO, R ;
NEYATANI, Y .
PHYSICAL REVIEW LETTERS, 1994, 72 (23) :3662-3665
[17]   QUANTITATIVE PREDICTIONS OF TOKAMAK ENERGY CONFINEMENT FROM FIRST-PRINCIPLES SIMULATIONS WITH KINETIC EFFECTS [J].
KOTSCHENREUTHER, M ;
DORLAND, W ;
BEER, MA ;
HAMMETT, GW .
PHYSICS OF PLASMAS, 1995, 2 (06) :2381-2389
[18]   Interpretation of core localized Alfven eigenmodes in DIII-D and Joint European Torus reversed magnetic shear plasmas [J].
Kramer, G. J. ;
Nazikian, R. ;
Alper, B. ;
de Baar, M. ;
Berk, H. L. ;
Fu, G. -Y. ;
Gorelenkov, N. N. ;
McKee, G. ;
Pinches, S. D. ;
Rhodes, T. L. ;
Sharapov, S. E. ;
Solomon, W. M. ;
van Zeeland, M. A. .
PHYSICS OF PLASMAS, 2006, 13 (05)
[19]   BIG DEE - A FLEXIBLE FACILITY OPERATING NEAR BREAKEVEN CONDITIONS [J].
LUXON, JL ;
DAVIS, LG .
FUSION TECHNOLOGY, 1985, 8 (01) :441-449
[20]   Non-dimensional scaling of turbulence characteristics and turbulent diffusivity [J].
McKee, GR ;
Petty, CC ;
Waltz, RE ;
Fenzi, C ;
Fonck, RJ ;
Kinsey, JE ;
Luce, TC ;
Burrell, KH ;
Baker, DR ;
Doyle, EJ ;
Garbet, X ;
Moyer, RA ;
Rettig, CL ;
Rhodes, TL ;
Ross, DW ;
Staebler, GM ;
Sydora, R ;
Wade, MR .
NUCLEAR FUSION, 2001, 41 (09) :1235-1242