Recent Progress in JET on Heating and Current Drive Studies in View of ITER

Experiments have been performed investigating the use of Ion Cyclotron Current Drive (ICCD) for sawtooth destabilization. The analysis allows for a generalization to any method capable of driving current close to the q=1 surface. A detailed study of the inverted ICRF heating scenarios, to be used in the hydrogen phase of ITER, shows the sensitivity of such scenarios to small concentrations of impurities having the same charge to mass ratio as the D minority ions. Their presence prevents any D minority heating, as the fast wave cannot longer reach the D ion cyclotron resonance layer. This has possible implications for the choice of the ICRF heating scenario in the hydrogen phase of ITER. An improved understanding has been obtained for the evolution of the density in the Scrape Off Layer (SOL) with strong gas puffing (to improve coupling) during high power Low Hybrid (LH) operation. Agreement with experiment can only be obtained assuming that LH power losses in the SOL increase ionization.
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