Oscillations of a bounded plasma in the lower-hybrid range

Q-machine experiments are described in which discrete resonant modes characteristic of the finite length and radius of a plasma column in which (ωpe/ωce)2<<1 are excited by an inductive coupler in the lower-hybrid range of frequencies. The experimental results are in agreement with an analysis in which ion effects and electron thermal effects are taken into account. Inductive coupling is found to give high-efficiency excitation of single modes without resonance cones. The dependence of mode properties on plasma parameters and geometric parameters is examined in the linear regime and the relation of these experiments to plasma heating and to the suppression of drift instabilities by lower-hybrid fields is discussed.