BREAKING OF RESONANTLY EXCITED ELECTRON-PLASMA WAVES

Simulations of high-amplitude electron plasma waves have been performed by solving the Vlasov equation numerically to clarify the mechanism of wave breaking in smooth density profiles. We show that wave breaking exists as a phenomenon which is distinct from incoherent hot-electron generation and which has a clear meaning in a kinetic theory: By trapping of entire bunches of electrons in the wave potential the latter is heavily disturbed and becomes irregular. In contrast to hot-electron generation these electron bunches are not accelerated to high velocities. An analytic criterion for wave breaking is derived which is consistent with the numerical simulations.