Role of the Edge and Scrape-Off Layer Plasma in Lower Hybrid Current Drive Experiment on Alcator C-Mod

被引：5
作者：
Baek, S. G. [1 ]
Biswas, B. [1 ]
Bonoli, P. T. [1 ]
Brunner, D. [1 ,2 ]
Faust, I. C. [1 ,3 ]
Hubbard, A. E. [1 ]
Hughes, J. W. [1 ]
LaBombard, B. [1 ]
Mumgaard, R. T. [1 ,2 ]
Porkolab, M. [1 ]
Shiraiwa, S. [1 ]
Wallace, G. M. [1 ]
Wukitch, S. J. [1 ]
机构：
[1] MIT, Plasma Sci & Fus Ctr, 77 Massachusetts Ave, Cambridge, MA 02139 USA
[2] Commonwealth Fus Syst, Cambridge, MA 02139 USA
[3] Max Planck Inst Plasma Phys, D-85748 Garching, Germany
来源：
23RD TOPICAL CONFERENCE ON RADIOFREQUENCY POWER IN PLASMAS | 2020年 / 2254卷
关键词：
PARAMETRIC-INSTABILITIES;
D O I：
10.1063/5.0014299
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：
This paper reports the latest lower hybrid current drive (LHCD) experimental and modeling investigations conducted on Alcator C-Mod, which further elucidates the role of the scrape-off layer (SOL) in determining the magnitude and profile of wave power deposition. In the latest C-Mod LHCD experiment, with a proper management of the SOL plasma, a recovery of efficient current drive is observed in a diverted configuration at densities exceeding the previously identified LH density limit of (n) over tilde (e) approximate to 1.0x10(20) m(-3). By operating at higher current, i.e., at lower Greenwald fraction, the SOL width is reduced and the turbulence level is minimized. Under this condition, parasitic wave power losses occurring in the edge/SOL region are found to be minimized. In our modeling study, a shift or spread in the poloidal mode number by the SOL turbulence is investigated in order to better match the experimental power deposition profile with an available raytracing/Fokker-Planck model. The approach is to introduce an additional spectral broadening mechanism by launching the rays with a non-negligible poloidal wavenumber component while preserving the launched n// power spectrum. This approach contrasts to spectral broadening achieved in the n// space. An initial modeling investigation on the C-Mod plasma reproduces an experimental on-axis power deposition profile.
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页数：8
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