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Title: Prompt Loss of Energetic Ions during Early Neutral Beam Injection in the National Spherical Torus Experiment

Early neutral-beam injection is used in the National Spherical Torus Experiment (NSTX) to heat the electrons and slow current penetration which keeps q(0) elevated to avoid deleterious MHD activity and at the same time reduces Ohmic flux consumption, all of which aids long-pulse operation. However, the low plasma current (I{sub p} {approx} 0.5 MA) and electron density (n{sub e} {approx} 1 x 10{sup 13} cm{sup -3}) attending early injection lead to elevated orbit and shine through losses. The inherent orbit losses are aggravated by large excursions in the outer gap width during current ramp-up. An investigation of this behavior using various energetic particle diagnostics on NSTX and TRANSP code analysis is presented.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
838508
Report Number(s):
PPPL-4060
TRN: US0600139
DOE Contract Number:
AC02-76CH03073
Resource Type:
Technical Report
Research Org:
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 74 ATOMIC AND MOLECULAR PHYSICS; BEAM INJECTION; ELECTRIC CURRENTS; ELECTRON DENSITY; ELECTRONS; TAIL IONS Charge Exchange; Injection, Neutral Beam; Spherical Torus