Impact of β n and spectrum of n = 1 applied fields on fast ion losses in DIII-D

Nuclear Fushion

article

K.R. Gage¹  X. Chen²  M. Van Zeeland²  W.W. Heidbrink¹  J. Hanson³  B. Lyons²  D.C. Pace²  J. Galdon-Quiroga⁴  M. Garcia-Munoz⁴ 

[1] University of California;General Atomics;Columbia University;University of Seville;Max Planck Institute for Plasma Physics

关键词: energetic particles;    tokamaks;    fast ion losses;    magnetic perturbations;   

DOI  :  10.1088/1741-4326/acb21f

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

The effect ofn= 1 magnetic perturbations (MPs) on prompt fast ion losses in DIII-D has been investigated using the light ion beam probe technique. The effect of normalized beta,β _n , and the plasma response to the MPs is studied for several MP spectra. Magnetics data show a strong dependence of plasma response toβ _n that depends on the phase difference in perturbation coils, Deltaphi_{mathrm{UL}} . For most phases, the response increases withβ _n , however, the response is suppressed for phases between 180^∘ and 240^∘. Experimental data from scintillator based fast ion loss detectors shows that relative fluctuation of lost ions (20%–30% of the steady signal) does not diminish across the L- to H-mode transition for Deltaphi_{mathrm{UL}} = 240^{circ} , despite the 34% decrease in radial response field and 50% decrease in poloidal response field. Simulations of the DIII-D discharges using M3D-C1 and ASCOT5 find that prompt losses from neutral beam injection in each investigated case hit the first wall at several concentrated locations: the vessel floor, midplane diagnostic ports, vessel ceiling, and inner wall. Simulated losses from co-injection neutral beams are born outside the last closed flux surface, corresponding to radial orbit displacements of 3–6 cm due to the MPs.

【 授权许可】

Unknown