Vlasov-Maxwell simulations of high-frequency longitudinal waves in a magnetized plasma

The plasma response to the injection of a propagating purely electrostatic wave of finite amplitude is investigated by means of a kinetic code which solves the Vlasov equations for electrons and ions in the three-dimensional (one spatial and two in velocity, 1D2V) phase space, self-consistently coupled to the Maxwell equations. The plasma is uniformly magnetized, and the wave frequency close to the cold upper-hybrid resonance omega(0)=rootomega(pe)(2)+omega(ce)(2) is considered. Coherent structures are formed in the phase space that would be completely missed by a hydrodynamic analysis. In particular, in the early stage of the interaction, the initially unperturbed equilibrium electron distribution is strongly affected as a whole by the pump, taking a ringlike shape in the velocity plane transverse to the magnetic field. Then, a sort of instability occurs, leading to the broadening and flattening of the electron distribution.