ICRF Wall Conditioning: Present Status and Developments for Future Superconducting Fusion Machines
- Laboratory for Plasma Physics-ERM/KMS, Association Euratom-Belgian State, 1000 Brussels (Belgium)
- Max-Planck Institut fuer Plasmaphysik, Euratom Association, 85748 Garching (Germany)
- Institut fuer Energieforschung-Plasmaphysik FZ Juelich, Euratom Association, 52425 Juelich (Germany)
ITER and future superconducting fusion machines need efficient wall conditioning techniques for routine operation in between shots in the presence of permanent high magnetic field for wall cleaning, surface isotope exchange and to control the in-vessel long term tritium retention. Ion Cyclotron Wall Conditioning (ICWC) based on the ICRF discharge is fully compatible and needs the presence of the magnetic field. The present paper focuses on the principal aspects of the ICWC discharge performance in large-size fusion machines: (i) neutral gas RF breakdown with conventional ICRF heating antennas, (ii) antenna coupling with low density ({approx}10{sup 17} m{sup -3}) RF plasmas and (iii) ICWC scenarios with improved RF plasma homogeneity in the radial and poloidal directions. All these factors were identified as crucial to achieve an enhanced conditioning effect (e.g. removal rates of selected 'marker' masses). All the observed effects are analyzed in terms of RF plasma wave excitation/absorption and compared with the predictions from 1-D RF full wave and 0-D RF plasma codes. Numerical modeling and empirical extrapolation from the existing machines give good evidence for the feasibility of using ICWC in ITER with the main ICRF antenna.
- OSTI ID:
- 21335698
- Journal Information:
- AIP Conference Proceedings, Vol. 1187, Issue 1; Conference: 18. topical conference on radio frequency power in plasmas, Gent (Belgium), 24-26 Jun 2009; Other Information: DOI: 10.1063/1.3273720; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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