Ponderomotive force of an ion cyclotron wave in a two-ion species plasma

The ponderomotive force experienced by an ion in a left circularly polarized wave changes sign as the frequency increases from below to above the ion cyclotron frequency. If the wave frequency is chosen to lie between the ion cyclotron frequencies of two different isotopes, then the ponderomotive force tends to separate the two species in space. As a result, the index of refraction is modified. Self-consistent solutions of the nonlinear wave equation taking into account both effects are obtained analytically and numerically. The ratio of the densities of the two ions is proportional to exp[mE2(z)/4γ(1-γ)αB20kT/sub i/], where E(z) is the amplitude of the wave, B0 is the magnetic field, and T/sub i/ is the temperature of the ions, m=2m1m2/(m1+m2), α=(m-italic1-m2)/(m1+m2), and γ=(omega-Ω2)/