LOW-ENERGY PARTICLE OSCILLATIONS AND CORRELATIONS WITH HYDROMAGNETIC-WAVES IN THE JOVIAN MAGNETOSPHERE - ULYSSES MEASUREMENTS

We report on measurements of energetic particle modulations (ions and electrons with energies E > 50. keV) observed by the heliosphere instr ument for spectra, composition, and anisotropy at low energies (HI-SCA LE) aboard the Ulysses spacecraft that were associated with the only h ydromagnetic (HM) wave event measured inside the Jovian magnetosphere by the Ulysses magnetometer investigation. This HM-wave event occurred during the high latitude outbound pass of the spacecraft in the dusk sector of the planet at distances between 65 and 68 Jovian radii (R(J) ) and at southern magnetic latitudes between 27 degrees and 32 degrees . We show that the approximately 5-min oscillations that occurred for about an hour in the north-south component of the magnetic field are w ell correlated with variations of the energetic particle fluxes at sma ll pitch angles. The detection of the narrow angle ion beams by the HI -SCALE instrument occurs at the intersection between two angular spin sectors. The small-amplitude waves vary the magnetic field direction s ufficiently that the beam is directed primarily toward one sector and then the other, and back again. Possible mechanisms for the HM-wave ge neration are explained. We show that the HM waves are most likely to b e generated by the presence of magnetospheric heavy ions (i.e., sulfur or oxygen) with energies in the range of a few keV.