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Title: Numerical investigation of fast-wave propagation and radio-frequency sheath interaction with a shaped tokamak wall

Interactions between propagating fast waves and radio-frequency (RF) sheaths in the ion cyclotron range of frequencies are numerically investigated based on a cold fluid plasma model coupled with a sheath boundary condition. In this two-dimensional study, the capability of the finite element code rfSOL, which was developed in previous numerical work, is extended to analyze self-consistent RF sheath-plasma interaction problems in a tokamak with a non-circular cross-section. It is found that a large sheath voltage is generated near the edges of the limiter-shaped deformation as a result of the conversion from fast to slow waves on the sheaths. The sheath voltage associated with this conversion is particularly significant in the localized region where the contact angle between the magnetic field line and the conducting wall varies rapidly along the curved sheath surface, which is consistent with the results in previous one-dimensional theoretical work. The dependences of the RF sheaths on various parameters in plasma such as the toroidal wavenumber, edge plasma density, and the degree of the RF wave absorption in the core region are also examined in detail.
Authors:
 [1] ; ;  [2]
  1. Department of Mechanical Information Science and Technology, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka 820-8502 (Japan)
  2. Lodestar Research Corporation, 2400 Central Avenue P-5, Boulder, Colorado 80301 (United States)
Publication Date:
OSTI Identifier:
22490009
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 7; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABSORPTION; BOUNDARY CONDITIONS; COLD PLASMA; CROSS SECTIONS; DEFORMATION; ELECTRIC POTENTIAL; FINITE ELEMENT METHOD; INTERACTIONS; ION PLASMA WAVES; MAGNETIC FIELDS; ONE-DIMENSIONAL CALCULATIONS; PLASMA DENSITY; PLASMA SHEATH; RADIOWAVE RADIATION; TOKAMAK DEVICES; TWO-DIMENSIONAL CALCULATIONS; WAVE PROPAGATION