OBLIQUE EMISSION OF WHISTLER-MODE WAVES AROUND INTERPLANETARY SHOCKS

We present a study of whistler-mode wave generation and wave particle interaction in the vicinity of interplanetary shocks as observed by th e Ulysses spacecraft. Generally the whistler-mode waves (measured in t he frequency range 0.22-448 Hz) are observed downstream of the shocks where they persist for some hours. From the electron distribution func tions (EDF) in the energy range 1.6 to 862 eV measured by the spacecra ft, we compute the wave growth rate of the electromagnetic electron cy clotron and Landau instabilities for the case of oblique propagation o f the waves with respect to the interplanetary magnetic held (IMF) B. In general, in agreement with the wave measurements, the instability g rows mostly downstream of the shock fronts. Following the wave activit y, velocity space diffusion of the electrons results in a marginally s table state with some sporadic fluctuations.