Plasma volume control in hybrid-type beam-plasma systems

Hybrid-type generators of non-equilibrium low-temperature plasmas are considered in the context of possible ways to control the plasma volume location in setup working chambers as well as plasma particle concentrations and fluxes. Planar and coaxial chambers were used in experiments with plasmas excited by the joint action of non-relativistic electron beams in combination with capacitive RF gas discharges on gases of forevacuum pressure. The electron-beam injection into the discharge was found to rearrange the plasma volume and affect both the plasma column and sheaths, resulting in the dark and bright zone replacement. When the beam scans over the plasma volume, these zones follow the beam trajectory. Electron heating, plasma-generating gas heating, and extra gas molecule excitation explain the external RF-electromagnetic field influence on the preliminarily excited electron-beam plasma within the pressure range 0.1–10 Torr. The effect turned out to be mostly pronounced at upper pressures of this range and at higher gas temperatures. Physical models describing the experimentally observed phenomena and effects were proposed and used in computer simulations within wide ranges of controllable parameters responsible for the hybrid plasma properties. Effects of plasma-generating gas pressure, gas heating, external electromagnetic field, and mass-transfer controlled by the ambipolar diffusion on plasma particle concentrations were estimated both separately and self-consistently.