  We study the quasineutral limit of the isothermal Euler-Poisson system
describing a plasma made of ions and massless electrons. The analysis is
achieved in a domain of $\R^3$ and thus extends former results by Cordier and
Grenier [Comm. Partial Differential Equations, 25 (2000), pp.~1099--1113], who
dealt with the same problem in a one-dimensional domain without boundary.
