Open AccessEnhanced Conversion of Thermal Electron Bernstein Waves to the Extraordinary Electromagnetic Mode on the National Spherical Torus Experiment (NSTX)
Author(s) -
G. Taylor,
P.C. Efthimion,
B. Jones,
B. LeBlanc,
Jason Wilson,
J.B. Wilgen,
G. L. Bell,
T. S. Bigelow,
R. Maingi,
D.A. Rasmussen,
Richard Harvey,
A. P. Smirnov,
F. Paoletti,
S.A. Sabbagh
Publication year - 2002
Publication title -
osti oai (u.s. department of energy office of scientific and technical information)
Language(s) - English
Resource type - Reports
DOI - 10.2172/809850
Subject(s) - limiter , torus , atomic physics , electron , physics , thermal , boron nitride , mode (computer interface) , materials science , computational physics , nuclear physics , geometry , nanotechnology , thermodynamics , mathematics , electrical engineering , computer science , engineering , operating system
A four-fold increase in the conversion of thermal electron-Bernstein waves (EBW) to the extraordinary mode (X-mode) was measured when the density scale length (L subscript ''n'') was progressively shortened by a local Boron nitride limiter in the scrape-off of an ohmically heated National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng, et al., Proceedings 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The maximum conversion efficiency approached 50% when L subscript ''n'' was reduced to 0.7 cm, in agreement with theoretical predictions that used locally measured L subscript ''n''. Calculations indicate that it is possible to establish L subscript ''n'' < 0.3 cm with a local limiter, a value predicted to attain approximately 100% EBW conversion to the X-mode in support of proposed EBW heating and current drive scenarios
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