Non-Linear Processes Associated with the Generation of Whistler Waves and their Effects on Electrons

Satellite observations in the inner magnetosphere have shown the presence of a highly anisotropic temperature distribution with perpendicular temperature about 10 times the parallel temperature. A linear theory and two-dimensional particle in cell simulation study has been carried out for this event to understand the physics of the wave generation, saturation and energy redistribution. The theoretical results show that for this event the anisotropic electron distribution can linearly excite obliquely propagating whistler mode waves in the upper band, i.e., greater than one-half the electron gyrofrequency. Non-linear processes excite waves in the lower band, i.e., less than one-half the electron gyrofrequency. The instability saturates by a combination of a decrease in the anisotropy of the mid-energy electrons as well as by heating of the cold electron population. The saturation time scale indicates that the temperature anisotropy of the mid-energy electrons must have a refresh rate of about 0.1 seconds in order to maintain the unstable distribution function.