A comparative study of energy and pitch angle diffusion during cyclotron resonance

Abstract

Adopting linear and non-linear theories of wave-particle interaction, the relative importance of pitch angle diffusion over particle energy diffusion is examined for different ELF/VLF waves at different equatorial and off-equatorial locations for <i>L</i> values lying between 2 and 8. The result shows that the pitch angle diffusion is important in the plasmasphere where <i><img src='http://www.niscair.res.in/jinfo/sigma1.gif' border=0></i> <img src='http://www.niscair.res.in/jinfo/lessequals.gif' border=0> 0.5, and the energy diffusion is important outside the plasmasphere where <i><img src='http://www.niscair.res.in/jinfo/sigma1.gif' border=0></i> = 0.6-0.8 (here <i><img src='http://www.niscair.res.in/jinfo/sigma1.gif' border=0></i> = <i>f</i>/<i>f</i>_H, <i>f</i> being the wave frequency and <i>f</i>_H, the electron gyrofrequency). As such, the result indicates the dominance of wavegrowth over particle precipitation outside the plasmasphere and is useful for interpretation of high latitude and polar emissions.