Effects of nonlinear Alfven wave interaction on particle diffusive shock acceleration. The Earth's bow shock

We investigate the role of nonlinear Alfven-wave interaction in the diffusive shock acceleration of solar-wind ions at the Earth's bow shock. Allowance for the nonlinear wave interaction through induced scattering and two-quanta absorption at plasma parameters beta less than or similar to 0.1 is shown to limit the Alfven-wave amplitude deltaB to deltaB less than or similar to B, whereas the quasi-linear approach predicts the generation of waves with amplitudes much larger than the diffusive shock magnetic field strength B. The nonlinear interaction results in spectral wave energy transfer to lower frequencies, which yields a significant increase in the particle acceleration rate. (C) 2002 MAIK "Nauka/Interperiodica".