Quasineutral limit for Vlasov-Poisson with Penrose stable data

We study the quasineutral limit of a Vlasov-Poisson system that describes the dynamics of ions in a plasma. We handle data with Sobolev regularity under the sharp assumption that the profiles in velocity of the initial data satisfy a Penrose stability condition. As a byproduct of our analysis, we obtain a well-posedness theory for the limit equation (which is a Vlasov equation with Dirac measure as interaction kernel), for such data.