Nonlinear evolution of the unmagnetized ion Rayleigh–Taylor instability

The nonlinear evolution of the unmagnetized ion Rayleigh–Taylor instability is investigated. A nonlinear state corresponding to localized clumps of high-density plasma is obtained analytically. The characteristic scale size of the clumps is given by Δ∼D(gLn)−1/2, where g is the gravitational acceleration, Ln is the density gradient scale length, and D is a diffusion coefficient associated with the short-scale dissipation processes in the system. It is shown numerically that this nonlinear state may be both accessible and stable.