Transconductance properties of plasmas

Radio-frequency effects arising from motions of the electrons and ions in plasmas are reviewed. Starting with cases of simple straight line orbits, the relationship between theory and experiment is cited in regard to wave dispersion, damping, amplification, and radiation. Circular and spiral orbits as well as linear and drifting-linear vibration orbits are considered. These examples show the common properties that linear drifting can produce damping or amplification while periodicities or near periodicities produce radiative coupling. The insight thus gained leads to some concluding remarks concerning more general orbits.