Obliquely propagating whistler instability in an inhomogeneous plasma penetrated by a helical electron beam

Abstract

The excitation of the whistler instability due to normal gyroresonant interaction is studied in a warm inhomogeneous plasma in the presence of a helical electron beam. The results show that it is possible to excite oblique whistler waves propagating at large angles with respect to the ambient magnetic field. It is found that the inhomogeneity increases the frequency and growth rate of the instability.