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Title: Radio-frequency sheaths physics: Experimental characterization on Tore Supra and related self-consistent modeling

During the 2011 experimental campaign, one of the three ion cyclotron resonance heating (ICRH) antennas in the Tore Supra tokamak was equipped with a new type of Faraday screen (FS). The new design aimed at minimizing the integrated parallel electric field over long field lines as well as increasing the heat exhaust capability of the actively cooled screen. It proved to be inefficient for attenuating the radio-frequency (RF)-sheaths on the screen itself on the contrary to the heat exhaust concept that allowed operation despite higher heat fluxes on the antenna. In parallel, a new approach has been proposed to model self-consistently RF sheaths: the SSWICH (Self-consistent Sheaths and Waves for IC Heating) code. Simulations results from SSWICH coupled with the TOPICA antenna code were able to reproduce the difference between the two FS designs and part of the spatial pattern of heat loads and Langmuir probe floating potential. The poloidal pattern is a reliable result that mainly depends on the electrical design of the antenna while the radial pattern is on the contrary highly sensitive to loosely constrained parameters such as perpendicular conductivity that generates a DC current circulation from the private region inside the antenna limiters to the freemore » scrape off layer outside these limiters. Moreover, the cantilevered bars seem to be the element in the screen design that enhanced the plasma potential.« less
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3]
  1. CEA, IRFM, F-13108 saint-Paul-Lez-Durance (France)
  2. Department of Electronics Politecnico di Torino, Torino (Italy)
  3. IJL UMR 7198, U. de Lorraine P2M, Fac. Des Sciences, BP 70239, F-54506 Vandoeuvre Cedex (France)
Publication Date:
OSTI Identifier:
22299952
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 6; Other Information: (c) 2014 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; ANTENNAS; DESIGN; HEAT FLUX; HEATING LOAD; ICR HEATING; LANGMUIR PROBE; LIMITERS; PLASMA POTENTIAL; PLASMA SCRAPE-OFF LAYER; RADIOWAVE RADIATION; SIMULATION; TORE SUPRA TOKAMAK