Edge Plasma Heating via Cyclotron Harmonic Interaction

Energy absorption in the edge region via cyclotron harmonic interaction during plasma heating with the ion-cyclotron range of frequencies is examined. It is shown that the electric field ripple caused by the closely spaced Faraday-shield conductors gives rise to large effective perpendicular wave numbers, resulting in strong cyclotron harmonic damping. For the parameters of the ASDEX tokamak, carbon impurity ions with $Z=5\mathrm{}$ and an initial perpendicular energy of 1 eV could be accelerated to energies in excess of 1 keV in less than 10 μs (corresponding to about 100 cyclotron orbits).