Mass separation by a wave ponderomotive force in a plasma

Mass separation, separation of particles of different mass, is a crucial process in a variety of societal applications [1]. In a significant number of techniques electromagnetic forces are exerted on charged particles or plasmas. Waves at the cyclotron frequency resonance are attempted for mass separation by specificall heating one species. Another way [2, 3] to use waves is by the ponderomotive force by standing shear Alfven waves also near the ion cyclotron resonance [4]. Standing waves can push ions of a small mass difference into opposite directions, if their cyclotron frequency is at opposite sides of the wave frequency. Electrostatic self-fields by the plasma are expected to compete in an unfavourable way with the ponderomotive force and may destroy the mass separation process. We examine theoretically the combined effect of the ponderomotive force and the electrostatic self-fields. We show that parameters can be chosen so that the electrostatic self-fields do not impede but rather support the separation process.