Abstract
The normal mode expansion method for the Vlasov equation has been developed to multispecies plasmas in an infinite system. The perturbed charge density for the Vlasov-Poisson system in multispecies plasmas is found be the same form as the perturbed distribution function in a single species plasma. The eigenfunctions and adjoint eigenfunctions, and the orthogonality relations between them have been derived. The complete set of eigenfunctions for the charge density is constructed, which has been applied for the initial value problems. The collective discrete mode shows a singularity when the initial beam velocity coincides with the discrete eigenvalue. The continuum contribution consists of the ballistic mode and pure continuum contribution. Scalar potential and each species distribution function are also solved making use of the complete set of eigenfunctions.
