Plasma heating above the lower hybrid frequency by linear wave absorption

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Abstract
The possibility of heating collisionless toroidal plasmas to high temperatures by means of linear wave absorption above the lower hybrid frequency is discussed. This absorption is mainly due to electron Landau damping and ion damping is neglected. Two methods of heating are considered, propagating a wave across the plasma column and exciting toroidal modes. WKB solutions of the first method show that the incident wave must be within a narrow range of kz for its energy to be uniformly deposited into the plasma. Toroidal mode solutions indicate that this band of kz may be significantly widened by lower kz waves which drive slightly damped toroidal modes. The conditions on kz for accessibility and heating are calculated and the advantages of such an approach are discussed.