现行托卡马克参数下的离散阿尔芬本征模

摘要/Abstract

摘要：

研究了在JT-60U运行参数下的α诱发的环向阿尔芬本征模(αTAE)，由其实验数据得到了s和α的径向剖面(s=rdq/qdr，α=-q²Rdβ/dr )。发现存在α极大值，尤其是在反剪切等离子体和高性能位形下。这证实了托卡马克中存在αTAE的全域捕获条件。在现行托卡马克中发现了多支αTAE。此外，还考察了在中性束注入实验过程中αTAE随时间的变化特性。

关键词: 阿尔芬波, MHD不稳定性, 托卡马克

Abstract:

The α-induced toroidal Alfvén eigenmode (αTAE) is investigated upon the operation parameters of JT-60U. The radial s and α profiles (s=rdq/qdr, α=–q²Rdβ/dr) are obtained via the data from experiments. There exists the α maximum, especially in the reversed shear plasmas and high performance configurations, which supports the globally trapped condition of the αTAE in tokamaks. Mutiple branches of αTAEs are found in present tokamaks. Furthermore, the time-variation of αTAE during neutral beams injection presented.

Key words: Alfvén waves, MHD instability, Tokamak

中图分类号:

O534+.2

姚龙宝, 胡双辉, 王一如, 陈淑平. 现行托卡马克参数下的离散阿尔芬本征模[J]. 核聚变与等离子体物理, 2012, 32(1): 8-14.

YAO Long-bao, HU Shuang-hui, WANG Yi-ru, CHEN Shu-ping. Discrete Alfvén eigenmodes in present tokamaks[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2012, 32(1): 8-14.

参考文献

[1] H Alfvén. Existence of electromagnetic-hydrodynamic waves [J]. Nature, 1942, 150: 406.

[2] Cheng C Z, Chen L, Chance M S. High-n ideal and resistive shear alfvén waves in tokamak [J]. Ann. Phys. (N.Y), 1985, 161: 21.

[3] Chen L. Theory of magnetohydrodynamic instabilities excited by energetic particles in tokamaks [J]. Phys. Plasmas, 1994, 1: 1519.

[4] Kimura H. Alfvén eigenmode and energetic particle research in JT-60U [J]. Nucl. Fusion, 1998, 38: 1303.

[5] Wong K L. Numerical simulation of ion cyclotron waves in tokamak plasmas [J]. Plasma Phys. Contr. Fusion, 1999, 41: R1.

[6] Carolipio E M. The toroidicity-induced Alfvén eigen- mode structure in DIII-D: Implications of soft X-ray and beam-ion loss data [J]. Phys. Plasmas, 2001, 8: 3391.

[7] Hu S, Chen L. Discrete Alfvén eigenmodes in high-β toroidal plasmas [J]. Phys. Plasmas, 2004, 11: 1.

[8] Kieras C E, Tataronis J A. The shear Alfvén continuous spectrum of axisymmetric toroidal equilibria in the large aspect ratio limit [J]. Plasma Physics, 1982, 28: 395.

[9] Piovesan P, Igochine V, Lauber P, et al. TAE internal structure through high-resolution soft X-ray measurements in ASDEX-Upgrade [J]. Nucl. Fusion, 2008, 48: 065001.

[10] Heidbrink W W, Van Zeeland M A. Central flattening of the fast-ion profile in reversed-shear DIII-D discharges [J]. Nucl. Fusion, 2008, 48: 084001.

[11] Hu S, Chen L. Discrete Alfvén eigenmodes excited by energetic particles in high-β toroidal plasmas [J]. Plasma Phys. Contr. Fusion, 2005, 47: 1251.

[12] Lee Y C, Van Dam J W. In proceedings of the finite beta theory workshop [M]. Varenna, edited by B. Coppi and W. Sadowski, U.S DOECONF-7709167, 1997. 93.

[13] ConnorJ W, Hastie R J, Taylor J B. High mode number stability of an axisymmetric toroidal plasma [J]. Proc. R. Soc. London, Ser. A , 1979, 365: 1.

[14] Connor J W, Hastie R J, Taylor J B. Shear, periodicity, and plasma ballooning modes [J]. Phys. Rev. Lett., 1978, 40: 396.

[15] Chen L, Zonca F. Theory of shear Alfvén waves in toroidal plasmas [J]. Phys. Scr., 1995, T60: 81.

[16] Kamada Y, Isayama A, Oikawa T, et al. Long sustainment of JT-60U plasmas with high integrated performance [J]. Nucl. Fusion, 1999, 39: 1845.

[17] Fujita T, Hatae T, Oikawa T, et al. High performance reversed shear plasmas with a large radius transport barrier in JT-60U [J]. Nucl. Fusion, 1998, 38: 207.

[18] Fujita T, Kamada Y, Ishida S, et al. High performance experiments in JT-60U reversed shear discharges [J]. Nucl. Fusion, 1999, 39(11Y): 302.

[19] Fujita T, Kamada Y. Sustainment of high confinement in JT-60U reversed shear plasmas [J]. Nucl. Fusion, 2002, 42: 180.

[20] Neudatchin S V, Takizuka T. Role of low order rational q-values in the ITB events in JT-60U reverse shear plasmas [J]. Nucl. Fusion, 2004, 44: 945.

[21] Fujita T, Ide S. Internal transport barrier for electrons in JT-60U reversed shear discharges [J]. Phys. Rev. Lett., 1997, 78: 2377.

[22] Gao Q D, Budny R V. Current pro?le control and optimization under dominant electron heating in HL-2A [J]. Nucl. Fusion, 2007, 47: 1318.

[23] Ding Bojiang, Kuang Guangli. Improved con?nement through internal transport barrier formation with lower hybrid current drive in the Hefei Tokamak-7 [J]. Phys. Plasmas, 2002, 9: 4996.

[24] Zhang Xian-Mei, WAN Bao-Nian. Estimation of charge exchange recombination emission based on diagnostic neutral beam on the experimental advanced superconducting tokamak [J]. Chin. Phys. Lett., 2007, 24: 487.

[25] Wu Bin, Niu Xingping. Reverse shear discharge simulation of EAST tokamak [J]. 33rd EPS, 2006, 30I(P-2): 181.

[26] Moyer R A, TynanG R, Holland C, et al. Increased nonlinear coupling between turbulence and low- frequency fluctuations at the L-H transition [J]. Phys. Rev. Lett., 2001, 87: 135001(1-4).

[27] Wagner F. Regime of improved confinement and high beta in neutral-beam-heated divertor discharges of the ASDEX tokamak [J]. Phys. Rev. Lett., 1982, 49: 1408.

[28] Keith H Burrell. Tests of causality: experimental evidence that sheared E×B flow alters turbulence and transport in tokamaks [J]. Phys. Plasmas, 1999, 6: 4418.

[29] Kusama Y, Nazikian R. Alfvén eigenmodes and their impact on plasma characteristics in JT-60U [C]. IAEA, 1999, EX8/6.

[30] Takechi M, Fukuyama A. Alfvén eigenmodes in reversed shear plasmas in JT-60U negative-ion-based neutral beam injection discharges [J]. Phys. Plasmas, 2005, 12: 082509.