Collisionless Heating of Electrons by Meandering Chaos and Its Application to a Low-Pressure Plasma Source

Abstract

Near a magnetic neutral line, where the magnetic field vanishes, the adiabatic invariants of charged particle motion are destroyed, and hence the number of degrees of freedom increases. When a radio-frequency electric field is applied to the system, the particle motion becomes strongly chaotic. This effect can be used to produce heat in a plasma in the absence of any collisional process. The kinetic entropy of an electron orbit increases very rapidly by the mixing effect. The velocity distribution is approximated by a Gaussian function, so the thermodynamic entropy production can also be estimated. This collisionless heating mechanism enables high-efficiency plasma production at a low gas pressure.