BREAKING OF RESONANTLY EXCITED ELECTRON-PLASMA WAVES

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