Analysis of Fast Minority Ion Distribution and Current Generation for ICRF and LH Heating

Dynamics of fast minority ions energised by ion cyclotron resonance and lower hybrid heating in tokamaks is investigated by cylindrical 20 Fokker-Planck and toroidal 30 Monte Carlo calculations. The power exchange between the waves and minority ions, the ensuing fast ion bootstrap current and the power deposition are calculated in the presence of fast ion radial diffusion and thermal minority ion source near the plasma edge. Both lower hybrid and ion cyclotron heating are observed to increase by increasing overlapping of the heating regimes and by radial diffusion, because of the enhanced diffusion of the ion cyclotron heated ions from their resonance region to the peripheral lower hybrid wave region, and diffusion of thermal ions from the plasma edge to the ion cyclotron heating region. The fast minority ion current is found to be strongly modified by the bootstrap current generation in the cyclotron heating region. An analytical expression to describe the RF-induced bootstrap current is presented.
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JETP96034 1.37 Mb