High-performance plasmas after pellet injections in Wendelstein 7-X

被引:78
作者
Bozhenkov, S. A. [1 ]
Kazakov, Y. [2 ]
Ford, O. P. [1 ]
Beurskens, M. N. A. [1 ]
Alcuson, J. [1 ]
Alonso, J. A. [3 ]
Baldzuhn, J. [1 ]
Brandt, C. [1 ]
Brunner, K. J. [1 ]
Damm, H. [1 ]
Fuchert, G. [1 ]
Geiger, J. [1 ]
Grulke, O. [1 ]
Hirsch, M. [1 ]
Hoefel, U. [1 ]
Huang, Z. [7 ]
Knauer, J. [1 ]
Krychowiak, M. [1 ]
Langenberg, A. [1 ]
Laqua, H. P. [1 ]
Lazerson, S. [1 ]
Marushchenko, N. B. [1 ]
Moseev, D. [1 ]
Otte, M. [1 ]
Pablant, N. [4 ]
Pasch, E. [1 ]
Pavone, A. [1 ]
Proll, J. H. E. [5 ]
Rahbarnia, K. [1 ]
Scott, E. R. [1 ]
Smith, H. M. [1 ]
Stange, T. [1 ]
von Stechow, A. [1 ]
Thomsen, H. [1 ]
Turkin, Yu [1 ]
Wurden, G. [6 ]
Xanthopoulos, P. [1 ]
Zhang, D. [1 ]
Wolf, R. C. [1 ]
机构
[1] Max Planck Inst Plasma Phys, D-17491 Greifswald, Germany
[2] LPP ERM KMS, Lab Plasma Phys, Brussels, Belgium
[3] CIEMAT, Lab Nacl Fus, Madrid, Spain
[4] Princeton Plasma Phys Lab, POB 451, Princeton, NJ 08543 USA
[5] Eindhoven Univ Technol, Eindhoven, Netherlands
[6] Los Alamos Natl Lab, Los Alamos, NM USA
[7] MIT, Plasma Sci & Fus Ctr, 77 Massachusetts Ave, Cambridge, MA 02139 USA
关键词
stellarator; improved confinement; heat transport; pellet injection; Wendelstein; 7-X; TRANSPORT-COEFFICIENTS; ENHANCED PERFORMANCE; ENERGY CONFINEMENT; DISCHARGES; SYSTEM; PHYSICS; REGION; JET;
D O I
10.1088/1741-4326/ab7867
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
A significant improvement of plasma parameters in the optimized stellarator W7-X is found after injections of frozen hydrogen pellets. The ion temperature in the post-pellet phase exceeds 3 keV with 5 MW of electron heating and the global energy confinement time surpasses the empirical ISS04-scaling. The plasma parameters realized in such experiments are significantly above those in comparable gas-fuelled discharges. In this paper, we present details of these pellet experiments and discuss the main plasma properties during the enhanced confinement phases. Local power balance is applied to show that the heat transport in post-pellet phases is close to the neoclassical level for the ion channel and is about a factor of two above that level for the combined losses. In comparable gas-fuelled discharges, the heat transport is by about ten times larger than the neoclassical level, and thus is largely anomalous. It is further observed that the improvement in the transport is related to the peaked density profiles that lead to a stabilization of the ion-scale turbulence.
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页数:15
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