Coupling and absorption of lower-hybrid waves in a thermonuclear plasma

The three important aspects namely, (i) accessibility, (ii) matching and (iii) absorption of the lower-hybrid waves in a thermonuclear plasma are discussed under idealized but physically pertinent conditions within the framework of linearized theory. Conditions are discussed under which it may be possible to launch slow-waves into the plasma using simple mechanical configurations which simultaneously fulfil the requirements of accessibility, and efficient matching. The principal absorption occurs via mode conversion followed by ion Landau damping at the cyclotron harmonics in the presence of magnetic field gradients. An attractive aspect of the above absorption mechanism is a more even deposition of the wave energy in the plasma volume even if only one rf frequency is used. (Auth.)