Open AccessEffect of Boronization on Ohmic Plasmas in NSTX
Author(s) -
C.H. Skinner,
H. Kugel,
R. Maingi,
W.R. Wampler,
W. Blanchard,
M.G. Bell,
R.E. Bell,
B. LeBlanc,
D. Gates,
S. M. Kaye,
P. H. LaMarche,
J. Ménard,
D. Mueller,
H.K. Na,
Norikazu Nishino,
S. F. Paul,
S. A. Sabbagh,
V. Soukhanovskii
Publication year - 2001
Language(s) - English
Resource type - Reports
DOI - 10.2172/781481
Subject(s) - plasma , boron , ohmic contact , materials science , atomic physics , torr , current density , torus , chemistry , physics , nuclear physics , nanotechnology , layer (electronics) , geometry , mathematics , organic chemistry , quantum mechanics , thermodynamics
Boronization of the National Spherical Torus Experiment (NSTX) has enabled access to higher density, higher confinement plasmas. A glow discharge with 4 mTorr helium and 10% deuterated trimethyl boron deposited 1.7 g of boron on the plasma facing surfaces. Ion beam analysis of witness coupons showed a B+C areal density of 10 to the 18 (B+C) cm to the -2 corresponding to a film thickness of 100 nm. Subsequent ohmic discharges showed oxygen emission lines reduced by x15, carbon emission reduced by two and copper reduced to undetectable levels. After boronization, the plasma current flattop time increased by 70% enabling access to higher density, higher confinement plasmas