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Title: Plasma interface of the EC waves to the LHD peripheral region

In order to realize an efficient ECRH and also to reduce stray radiation due to non-absorbed power during ECRH, it is necessary to excite a wave that is absorbed well near the electron cyclotron resonance. In the normal fusion magnetic field confinement machine and in the electron cyclotron frequency range, WKB approximation is valid almost all the way from antenna to the absorption region due to the large scale-length of the plasma density λ{sub n} and the magnetic shear τ{sub s} as compared with the local wavelength λ{sub 0}. In these situation, it is well known that the O/X mode propagates as O/X mode if τ{sub s} ≫ λ{sub 0}. Even in these situation, if τ{sub s} and λ{sub n} are comparable and |1/λ{sub O}−1/λ{sub X}|τ{sub s} ≪ 1, there still remains the question from where ”X” - or ”O” - mode become ”X” - or ”O” mode at the peripheral region. In order to simulate this situation, one dimensional full wave calculation code which solve electromagnetic wave equation under arbitrary magnetic field configuration and arbitrary density profile for a given polarization state are developed and incorporated in the upgraded ray tracing code LHDGauss. It is tried to find themore » density and shear scale lengths region where the mode mixing effect is not negligible.« less
Authors:
; ; ; ; ; ; ;  [1] ;  [2]
  1. National Institute for Fusion Science, Toki, 509-5292 (Japan)
  2. Grad. School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561 (Japan)
Publication Date:
OSTI Identifier:
22496229
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1689; Journal Issue: 1; Conference: 21. topical conference on radio frequency power in plasmas, Lake Arrowhead, CA (United States), 27-29 Apr 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ANTENNAS; COMPARATIVE EVALUATIONS; CONFINEMENT; CYCLOTRON FREQUENCY; DENSITY; ECR HEATING; ELECTROMAGNETIC RADIATION; ELECTRON CYCLOTRON-RESONANCE; ELECTRONS; INTERFACES; LENGTH; LHD DEVICE; MAGNETIC FIELD CONFIGURATIONS; MAGNETIC FIELDS; ONE-DIMENSIONAL CALCULATIONS; PLASMA DENSITY; SHEAR; STRAY RADIATION; WKB APPROXIMATION