Wave excitation by inhomogeneous suprathermal electron beams

Wave excitation by an inhomogeneous suprathermal electron beam in a homogeneous magnetized plasma is investigated. Not only is the beam density non-uniform, but the beaming electrons also have a sheared bulk velocity. The general dispersion equation including both electrostatic and electromagnetic effects is derived. Particular attention is paid to the whistler mode. It is found that the density-gradient and velocity-shear effects are important for waves with frequencies close to the lower-hybrid resonance frequency.