SOLAR ENERGETIC PARTICLES INSIDE MAGNETIC CLOUDS OBSERVED WITH THE WIND SPACECRAFT

Solar energetic particles can be used to probe the structure of magnet ic clouds. Since impulsive flare particles are accelerated within acti ve regions, their presence inside a magnetic cloud implies that the cl oud's magnetic field connects to an active region at the sun. We repor t on the flexes and composition of low energy ions inside 13 magnetic clouds observed with instrumentation on the Wind spacecraft from Novem ber 1994 to February 1997. The STEP subsystem of the EPACT experiment on Wind resolves He-3 and He-4 and the most abundant heavy ion species from similar to 20 keV/nucleon to similar to 1 MeV/nucleon. Using STE P, we are able to measure the energetic particle composition in an ene rgy range previously unexplored in the context of magnetic clouds. We find that when STEP measured significant ion fluxes inside a cloud, th ey were most likely from impulsive solar flares; this was the case in 4 events. We find that the 1/10/97 magnetic cloud decreased the interp lanetary fluxes of similar to 100 keV/nucleon ions by a factor of simi lar to 10(2); this was probably because the cloud disconnected Wind fr om the interplanetary particle source beyond 1 AU. In contrast, we obs erved particles from several impulsive solar flares inside the 10/18/9 5 event with fluxes similar to 10(3) higher than the fluxes measured i nside the 1/10/97 cloud.