Electron parametric instabilities of ultraintense short laser pulses propagating in plasmas

A general dispersion relation is given for electron parametric instabilities of an ultraintense circularly polarized wave propagating in a plasma. It is valid fur My plasma density and wave intensity and corresponds to a generalization of the Raman, relativistic modulational, relativistic filamentation, and two-plasmons instabilities. Its numerical resolution shows different zones of instability in the wave vector space. At high intensities, the zones extend and merge, with growth rates equal to a fraction of the wave frequency. At close-to-critical density and high intensity the instability leads to strong harmonic emission. Particle-in-cell simulations confirm the analytical results.