Nonlinear evolution of the Kruskal-Schwarzschild instability of a plasma above a vacuum

In this paper we consider the nonlinear development of the plasma Rayleigh-Taylor instability, also known as the Kruskal-Schwarzschild instability. Numerical calculations suggest that the plasma-vacuum interface, which initially takes the shape of an exponentially growing cosine function, will become multivalued after a while. Bubbles are seen to develop and to tend to at least partially detach themselves from the plasma. This paper gives a simple model of the process on the interface of a plasma layer with a vacuum. Profiles obtained are very similar to those found numerically by other authors. These multivalued profiles acquire a new symmetry in the semi-infinite plasma limit.