Observation of Efficient Lower Hybrid Current Drive at High Density in Diverted Plasmas on the Alcator C-Mod Tokamak

被引：33

作者：

Baek, S. G. ^{[1
]}

Wallace, G. M. ^{[1
]}

Bonoli, P. T. ^{[1
]}

Brunner, D. ^{[1
]}

Faust, I. C. ^{[1
,2
]}

Hubbard, A. E. ^{[1
]}

Hughes, J. W. ^{[1
]}

LaBombard, B. ^{[1
]}

Parker, R. R. ^{[1
]}

Porkolab, M. ^{[1
]}

Shiraiwa, S. ^{[1
]}

Wukitch, S. ^{[1
]}

机构：

[1] MIT, Plasma Sci & Fus Ctr, 77 Massachusetts Ave, Cambridge, MA 02139 USA

[2] Max Planck Inst Plasma Phys, D-85748 Munich, Bavaria, Germany

来源：

PHYSICAL REVIEW LETTERS | 2018年 / 121卷 / 05期

关键词：

SCRAPE-OFF-LAYER; PARAMETRIC-INSTABILITIES; HIGH-FIELD; WAVES; FREQUENCIES; TRANSPORT; PARTICLE; LIMIT;

D O I：

10.1103/PhysRevLett.121.055001

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Efficient lower hybrid current drive (LHCD) is demonstrated at densities up to (n) over bar (e) approximate to 1.5 x 10(20) m(-3) in diverted plasmas on the Alcator C-Mod tokamak by operating at increased plasma current-and therefore reduced Greenwald density fraction. This density exceeds the nominal "LH density limit" at (n) over bar (e) approximate to 1.0 x 10(20) m(-3) reported previously, above which an anomalous loss of current drive efficiency was observed. The recovery of current drive efficiency to a level consistent with engineering scalings is correlated with a reduction in density shoulders and turbulence levels in the far scrape-off layer. Concurrently, rf wave interaction with the edge and/or scrape-off-layer plasma is reduced, as indicated by a minimal broadening of the wave frequency spectrum measured at the plasma edge. These results have important implications for sustaining steady-state tokamak operation and indicate a pathway forward for implementing efficient LHCD in a reactor.

引用

页数：6

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