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Title: Influence of impurities on the transition from minority to mode conversion heating in ({sup 3}He)-H)- plasmas

Ion cyclotron resonance heating (ICRH) is one of the main auxiliary heating systems used in present-day tokamaks and is planned to be installed in ITER. In the initial full-field phase of ITER operating with hydrogen majority plasmas, fundamental resonance heating of helium-3 ions is one of a few ICRH schemes available. Past JET experiments with the carbon wall revealed a significant impact of impurities on the ICRH performance in ({sup 3}He)-H plasmas. A significant reduction of the helium-3 concentration, at which the transition from minority ion to mode conversion heating occurs, was found to be due to a high plasma contamination with carbon ions. In this paper we discuss the effect of Be and another impurity species present at JET after the installation of a new ITER-like wall on the transition helium-3 concentration in ({sup 3}He)-H plasmas. We suggest a potential method for controlling helium-3 level needed for a specific ICRH regime by puffing an extra helium-4 gas to the plasma.
Authors:
 [1] ;  [2] ;  [3]
  1. LPP-ERM/KMS, Association EURATOM-Belgian State, Trilateral Euregio Cluster Partner, Brussels (Belgium)
  2. Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Göteborg (Sweden)
  3. LPP-ERM/KMS, Association 'EURATOM-Belgian State', Trilateral Euregio Cluster Partner, Brussels (Belgium)
Publication Date:
OSTI Identifier:
22263868
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1580; Journal Issue: 1; Conference: 20. topical conference on radiofrequency power in plasmas, Sorrento (Italy), 25-28 Jun 2013; Other Information: (c) 2014 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AUXILIARY HEATING; CARBON; CARBON IONS; CONTAMINATION; HELIUM 3; ICR HEATING; IMPURITIES; ITER TOKAMAK; MODE CONVERSION; PLASMA