Bounce-averaged diffusion coefficients for superluminous wave modes in the magnetosphere

In this study, we present a first evaluation of bounce-averaged diffusion coefficients of superluminous wave (R-X and L-O) modes at two locations: L = 6.5 and 4.5. We show that, analogous to the local diffusion coefficients, bounce-averaged momentum diffusion coefficients play a dominant role for pitch angles alpha above a critical angle alpha(c), namely, > vertical bar vertical bar > . We also demonstrate that for a Gaussian distribution of wave normal angle theta (X = tan theta). diffusion coefficients are sensitively dependent on the peak X(m). As X(m) increases, and are found to increase in cases of interest: X(m) = tan 25 degrees, tan 45 degrees and tan 65 degrees. We have estimated wave amplitudes for particular stochastic acceleration timescale for 1 MeV electrons and found that the required wave amplitudes B(te) similar to 86 to similar to 170 pT for a timescale tau = 1 day. These results indicate that superluminous wave modes may have a significant potential for both stochastic acceleration of trapped electrons (with higher pitch angles) and loss process of untrapped electrons (with smaller pitch angles). (C) 2009 Elsevier Ltd. All rights reserved.