Obliquely propagating whistler mode waves in cold plasmas permeated by dilute low-β anisotropic plasmas

We analyse the growth rate of obliquely propagating whistler mode waves in a cold plasma that also contains some hot electrons in a bi-Maxwellian distribution. Approximate analytic expressions for the growth rate are derived explicitly. They are represented by elementary functions only, consisting of a Landau damping term and a cyclotron instability term. They are found to be valid for a wide range of wave normal angles. Landau damping in the oblique propagation does not always become larger even if the wave normal angles increase. The necessary conditions for the minimal parallel growth are Ω > 0.5Ω_e and T_≥> 2T in the bi-Maxwellian hot plasma. This method is applied to calculations of the net growth along the ray paths of obliquely propagating non-ducted whistler mode waves in a model magnetosphere.