Evolution of Coronal MHD Shocks into Interplanetary MHD Shocks

One of the fimdamental potential hazards to the “Fire” mission (Solar Probe) is the energetic particle environment near the sun. Heras et al., (1995), Sanahuja el al. (1995), and Sanahuja and Lario (1995) have modeled shock acceleration of low energy particles (< 2 MeV) due to fast ejects from the sun, One c@ical problem in this model, at the present time, is that no one has modeled coronal and heliospheric shock strengths as a finction of radial distances and ejects velocities. In this paper we take a normal ambient solar wind (with a coronal hole and helmet-streamer representative of solar minimum) and generate low velocity and high velocity ejects by imposing thermal pulses at the base of the helmet streamer. Our preliminary results show that the shocks formed at -2 & and their strengths (i.e. magnetosonic Mach number) increase as they propagate outward. These preliminary results will be very helpfil in defining an ener~etic particle environment close to the sun.