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Abstract

Plasma heating of a Tokamak plasma by wave coupling in the ion cyclotron range of frequency has been investigated during the last decade along several schemes: in a twoion plasma containing comparable amounts of the ion components, wave conversion heating is expected to couple the main part of the power to the electrons. For a small fraction of one of the two components, the power will be coupled by minority heating to the low density ion species. Heating of a single ion plasma requires power coupling at the second harmonic frequency. The theoretical basis for those three mechanisms will be qualitatively reviewed. Wave conversion heating has been particularly investigated in the TFR Tokamak. The experimental results will be reviewed underlining the important role played by metallic impurities on the evolution of ion and electron temperatures and the severe limitation on electron temperature observed in all conditions. The principal results on minority heating have been obtained on PLT and JET Tokamaks where up to 5 MW of radio frequency power have been coupled to the plasma. In both cases, evolution of the electron temperature is limited by the occurrence of large amplitude sawtooth oscillations. While the ion temperature reaches much larger values than the electron temperature in PLT, this is not the case in JET where the sawteeth determine also the evolution of the ion temperature. This can be explained by the large difference in the central power density in the two machines. Decay of the energy containment time is observed in all ion cyclotron heating experiments. This is particularly evidenced by the very small heating efficiency of JET outside the q = 1 surface. The experimental data obtained until now on second harmonic heating will be briefly summarized.

Additional information

Authors: ADAM J CEA, CENTRE D'ETUDES NUCLEAIRES DE CADARACHE, SAINT- PAUL-LEZ-DURANCE (FRANCE), CEA, CENTRE D'ETUDES NUCLEAIRES DE CADARACHE, SAINT- PAUL-LEZ-DURANCE (FRANCE)
Bibliographic Reference: PLASMA PHYSICS AND CONTROLLED FUSION, VOL. 29 (1987), NO. 4, PP. 443-472
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