Non-inductive plasma initiation and plasma current ramp-up on the TST-2 spherical tokamak

被引:37
|
作者
Takase, Y. [1 ]
Ejiri, A. [1 ]
Kakuda, H. [2 ]
Oosako, T. [1 ]
Shinya, T. [1 ]
Wakatsuki, T. [2 ]
Ambo, T. [1 ]
Furui, H. [1 ]
Hashimoto, T. [2 ]
Hiratsuka, J. [2 ]
Kasahara, H. [3 ]
Kato, K. [1 ]
Kumazawa, R. [3 ]
Moeller, C. P. [4 ]
Mutoh, T. [3 ]
Nakanishi, A. [1 ]
Nagashima, Y. [5 ]
Saito, K. [3 ]
Sakamoto, T. [1 ]
Seki, T. [3 ]
Sonehara, M. [2 ]
Shino, R. [2 ]
Togashi, H. [1 ]
Watanabe, O. [5 ]
Yamaguchi, T. [1 ]
机构
[1] Univ Tokyo, Grad Sch Frontier Sci, Kashiwa, Chiba 2778561, Japan
[2] Univ Tokyo, Grad Sch Sci, Kashiwa, Chiba 2778561, Japan
[3] Natl Inst Nat Sci, Natl Inst Fus Sci, Toki, Gifu 5095292, Japan
[4] Gen Atom Co, San Diego, CA 92186 USA
[5] Kyushu Univ, Appl Mech Res Inst, Kasuga, Fukuoka 8168580, Japan
基金
日本学术振兴会;
关键词
Tokamak devices - Electromagnetic induction - Magnetoplasma - Antenna arrays - Efficiency - Inductively coupled plasma;
D O I
10.1088/0029-5515/53/6/063006
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
Plasma current (I-p) start-up in a spherical tokamak (ST) by waves in the lower-hybrid (LH) frequency range was investigated on TST-2. Alowcurrent (similar to 1 kA) ST configuration can be formed bywaves over a broad frequency range (21 MHz-8.2 GHz in TST-2), but further Ip ramp-up (to similar to 10 kA) is most efficient with waves in the LH frequency range. I-p ramp-up to 15 kA was achieved with 60kW of net RF power P-RF in the fast wave (FW) polarization at 200MHz excited by the inductively coupled combline antenna. X-ray measurements showed that the photon flux and temperature are higher in the direction opposite to I-p, consistent with acceleration of electrons by a uni-directional RF wave. There is evidence that the LH wave is excited nonlinearly by the FW, based on the frequency spectra measured by magnetic probes. Similar efficiencies of I-p ramp-up were obtained with the inductive combline antenna and the dielectric-loaded waveguide array ('grill') antenna, and tendencies for the current drive efficiency to increase with plasma current and toroidal field were observed. During operation of the grill antenna, wavevector components were measured by an array of magnetic probes. Results were qualitatively consistent with expectations based on dispersion relations for the FW and the LH wave. A capacitively coupled combline antenna has been developed to improve coupling to the plasma and the wavenumber spectrum of the excited LH wave, and will be tested in 2013.
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页数:6
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