Properties of obliquely propagating chorus

Abstract

We discuss chorus wave magnetic and electric field polarizations as functions on angle of propagation relative to the ambient magnetic field B0. For the first time, it is shown using a cold plasma approximation that the general whistler wave has circularly polarized magnetic fields for oblique propagation. This theoretical result is verified by observations. The electric field polarization plane is not orthogonal to the wave vector k and is in general highly elliptically polarized. Both the magnetic and the electric polarizations have important consequences for cyclotron resonant electron pitch angle scattering and for electron energization, respectively. A special case of the whistler wave called the Gendrin mode is discussed.