Open AccessL-H Threshold Studies in NSTX
Author(s) -
S. Kaye,
R. Maingi,
D. J. Battaglia,
Robert B. Bell,
Choong-Seock Chang,
B. LeBlanc,
J. Hosea,
H. Kugel,
H. Meyer,
G.-Y. Park,
J. R. Wilson
Publication year - 2011
Language(s) - English
Resource type - Reports
DOI - 10.2172/1028184
Subject(s) - plasma , atomic physics , deuterium , lithium (medication) , physics , helium , power (physics) , computational physics , nuclear physics , thermodynamics , medicine , endocrinology
Recent experiments in the low aspect ratio National Spherical Torus Experiment (NSTX) have been run in support of the high priority ITER and ITPA issue of access to the H-mode. Specifically, a series of experiments showed reduced power threshold values for deuterium vs helium plasmas, and for plasmas with lower current, lower triangularity and with lithium conditioning. Application of n=3 fields at the plasma edge resulted in higher power thresholds. To within the constraints of temporal and spatial resolutions, no systematic difference in T{sub e}, n{sub e}, p{sub e}, T{sub i}, v or their derivatives was found in discharges that transitioned into the H-mode versus those at slightly lower power that did not. Finally, H{sub 98y,2} {approx} 1 confinement quality could be achieved for powers just above the threshold power in ELM-free conditions