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Title: Effect of the minority concentration on ion cyclotron resonance heating in presence of the ITER-like wall in JET

The most recent JET campaign has focused on characterizing operation with the 'ITER-like' wall. One of the questions that needed to be answered is whether the auxiliary heating methods do not lead to unacceptably high levels of impurity influx, preventing fusion-relevant operation. In view of its high single pass absorption, hydrogen minority fundamental cyclotron heating in a deuterium plasma was chosen as the reference wave heating scheme in the ion cyclotron domain of frequencies. The present paper discusses the plasma behavior as a function of the minority concentration X[H] in L-mode with up to 4MW of RF power. It was found that the tungsten concentration decreases by a factor of 4 when the minority concentration is increased from X[H] ≈ 5% to X[H] % 20% and that it remains at a similar level when X[H] is further increased to 30%; a monotonic decrease in Beryllium emission is simultaneously observed. The radiated power drops by a factor of 2 and reaches a minimum at X[H] ≈ 20%. It is discussed that poor single pass absorption at too high minority concentrations ultimately tailors the avoidance of the RF induced impurity influx. The edge density being different for different minority concentrations, it ismore » argued that the impact ICRH has on the fate of heavy ions is not only a result of core (wave and transport) physics but also of edge dynamics and fueling.« less
Authors:
; ; ;  [1] ; ; ; ; ; ; ; ; ; ;  [2] ; ; ; ;  [3] ;  [4] ;  [5] more »; « less
  1. LPP-ERM/KMS, Association Euratom-Belgian State, TEC Partner, Brussels (Belgium)
  2. Euratom-CCFE Fusion Association, Culham Science Centre (United Kingdom)
  3. MPI für Plasmaphysik Euratom Assoziation, Garching (Germany)
  4. Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland)
  5. IEK-4, EURATOM-FZJ, TEC Partner, Jülich (Germany)
Publication Date:
OSTI Identifier:
22263858
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:
74 ATOMIC AND MOLECULAR PHYSICS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; AUXILIARY HEATING; BERYLLIUM; CYCLOTRON RESONANCE; CYCLOTRONS; DEUTERIUM; EMISSION; HEAVY IONS; ICR HEATING; ITER TOKAMAK; L-MODE PLASMA CONFINEMENT; PLASMA; TUNGSTEN