  In this paper, we consider the quasineutral limit of the Euler-Poisson
equation for a clod, ion-acoustic plasma when the Debye length tends to zero.
When the ion-acoustic plasma is cold, the Euler-Poisson equation is
pressureless and hence fails to be Friedrich symmetrisable, which excludes the
application of the classical energy estimates method. This brings new
difficulties in proving uniform estimates independent of $\varepsilon$. The
main novelty in this article is to introduce new $\varepsilon$-weighted norms
of the unknowns and to combine energy estimates in different levels with
weights depending on $\varepsilon$. Finally, that the quasineutral regimes are
the incompressible Euler equations is proven for well prepared initial data.
