Quasi-neutral limit for Euler-Poisson system

This paper provides a rigorous proof of the quasi-neutral limit for the Eul er-Poisson system on a bounded domain in one space dimension. The most gene ral case is being considered when the plasma is sustained by ionization. A wide range of plasmas, from collisionless to highly collisional, is permitt ed. At the plasma center, the ions are assumed to be at rest, and essential ly quasi-neutral initial data are prescribed. The theorem asserts that the quasi-neutral limit is obtained until the ion velocity reaches the ion-soun d speed, In addition, formal matched asymptotic expansions are given which describe the solution in its passage from the plasma center to the wall.