Edge-Density-Profile Effects for Lower-Hybrid-Waveguide Coupling

摘要

The usual predictions of linear coupling theory for lower hybrid waves are altered by including an overdense edge plasma ( omega < omega /sub pe/) in the plasma model. Coupling is found to depend strongly on the value of the edge density, as well as the density gradient. The regimes, where one or the other of these parameters is important, are investigated. Typically, only the first few millimeters of the edge plasma is important in determining coupling. The major implications of the problem of coupling to an overdense plasma can be derived from a simple impedence matching argument. In general, coupling is optimum for an edge density, n sub 0 , determined by n sub 0 /n/sub c/ approx. = n/sub parallel/ exp 2 , where n/sub c/ = omega exp 2 m/sub e//4 pi e exp 2 and n/sub parallel/ is the parallel index of refraction of the lower hybrid wave. (ERA citation 06:021348)