Electromagnetic ion-cyclotron instability in a dusty plasma with product-bi-kappa distributions for the plasma particles

Abstract

We study the dispersion relation for parallel propagating ion-cyclotron (IC) waves in a dusty plasma, considering situations where the velocity dispersion along perpendicular direction is greater than along the parallel direction, and considering the use of product-bi-kappa (PBK) velocity distributions for the plasma particles. The results obtained by numerical solution of the dispersion relation, in a case with isotropic Maxwellian distributions for electrons and PBK distribution for ions, show the occurrence of the electromagnetic ion-cyclotron instability (EMIC), and show that the decrease in the kappa indexes of the PBK ion distribution leads to significant increase in the magnitude of the growth rates and in the range of wavenumber for which the instability occurs. On the other hand, for anisotropic Maxwellian distribution for ions and PBK distribution for electrons, the decrease of the kappa index in the PBK electron distribution contributes to reduce the growth rate of the EMIC instability, but the reduction effect is less pronounced than the increase obtained with ion PBK distribution with the same kappa index. The results obtained also show that, as a general rule, the presence of a dust population contributes to reduce the instability in magnitude of the growth rates and range, but that in the case of PBK ion distribution with small kappa indexes the instability may continue to occur for dust populations which would eliminate completely the instability in the case of bi-Maxwellian ion distributions. It has also been seen that the anisotropy due to the kappa indexes in the ion PBK distribution is not so efficient in producing the EMIC instability as the ratio of perpendicular and parallel ion temperatures, for equivalent value of the effective temperature.