Properties of Whistler Waves in Warm Electron Plasmas

Dispersion relation and electromagnetic properties of obliquely propagating whistler waves are investigated on the basis of a warm electron fluid model. The magnetic field of whistler waves is nearly circularly polarized with respect to the wave vector in a plasma where the electron plasma frequency Omega(pe) is much larger than the electron cyclotron frequency Omega(ce), and the magnetic field polarization can become elliptical, or even linear, polarization as Omega(pe) less than or similar to Omega(ce). In the plasmas with Omega(pe) < Omega(ce), the resonant frequency is about Omega(ce) cos theta, which is different from Omega(pe) cos theta predicted by the cold electron fluid model. Near the resonant frequency, the whistler wave approximates a quasi-magnetostatic mode, not a quasi-electrostatic mode in the cold electron plasmas. Moreover, the detailed mode properties are given in Earth's magnetosphere, the solar active region, and Jupiter's polar cap. Furthermore, the study proposes that the ratio of the electrostatic to electromagnetic component of the electric field can be used to distinguish the whistler mode from the Z-mode in the frequency range of Omega(pe) < omega < Omega(ce) in the solar active region and Jupiter's polar cap.