<B>Wave-Particle Interactions for <SUP>3</SUP>He-Rich Events and Large Solar Particle Events: ISEE-3</B> <PRE>B.T. Tsurutani<SUP>1,3</SUP>, L.D. Zhang<SUP>1</SUP>, Glenn M. Mason<SUP>2,4</SUP>, Gurbax Lakhina<SUP>1</SUP>, Tohru Hada<SUP>5</SUP>, John K. Arballo<SUP>1</SUP>, Ronald D. Zwickl<SUP>3</SUP> <SUP>1</SUP> Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 <SUP>2</SUP> Department of Physics, University of Maryland, College Park, Maryland 20742 <SUP>3</SUP> National Oceanic and Atmospheric Administration, Space Environment Laboratory, Code R/E/SE, Boulder, Colorado 80303 <SUP>4</SUP> Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 25742 <SUP>5</SUP> ESST Kyushu University, Kasuga 816-8580, Japan </PRE> <P align="justify"> ISEE-3 energetic particles and MHD waves are studied to investigate particle propagation and scattering between the source near the Sun and the Earth (1 AU). For <SUP>3</SUP>He rich events, simultaneous interplanetary magnetic spectra are measured. The interplanetary turbulence through which the particles have traversed is found to be fairly low. This can be interpreted as indicating that either low turbulence fields are necessary for the particles to propagate long (~1.3 AU) distances, or that the fields above active regions producing <SUP>3</SUP>He events have a lack of waves/turbulence. If the former is the case, there may be many <SUP>3</SUP>He events at the sun that are not detected at 1 AU. The largest solar particle events are analyzed to investigate the possibilities of local wave generation at 1 AU. No evidence for wave instability is found at either the leading edge or at the point of peak flux. Our results indicate that interplanetary solar wind "fossil" waves are the important scatterers for particles coming from the Sun to 1 AU, and it is the quiet to intermediate level of IMF activity that are associated with the <SUP>3</SUP>He scatter-free events. Lastly we intercompare the particle mean free paths calculated from resonant wave-particle interactions <img SRC="/ACE/ACE2000/abstracts/backups/Image1.gif" align=center> and from those derived from <SUP>3</SUP>He<SUP>++</SUP> intensity and anisotropy time profiles <img SRC="/ACE/ACE2000/abstracts/backups/Image2.gif" align=center>. By including measured wave polarization and wave <b>k</b> directions, we decrease the previously noted discrepancy between <img SRC="/ACE/ACE2000/abstracts/backups/Image1.gif" align=center> and <img SRC="/ACE/ACE2000/abstracts/backups/Image2.gif" align=center> by a factor of ~ 2. We note that <img SRC="/ACE/ACE2000/abstracts/backups/Image2.gif" align=center> is determined by the process of pitch angle scattering from ~ 0° to ~ 180°, while <img SRC="/ACE/ACE2000/abstracts/backups/Image1.gif" align=center> by that from ~ 0° to ~ < 90°. But the scattering across 90° pitch angle is a different process. Therefore the remaining discrepancy between <img SRC="/ACE/ACE2000/abstracts/backups/Image1.gif" align=center> and <img SRC="/ACE/ACE2000/abstracts/backups/Image2.gif" align=center> may lie in the fact that diffusion across 90° pitch angle is much slower than resonant scattering near 0° and 180° pitch angle.