Effects of the Interstellar Neutral Wind on the Structure of the Heliosphere - Laboratory Simulation

Abstract

The interaction between the solar wind and the local intersteller medium (LISM) involves the relaxation toward pressure equilibrium between the solar wind and the intersteller magnetized plasma. We have been doing a laboratory simulation of the heliosphere using a plasma gun and a plasma emitter which generates supersonic plasma flow. The result by a time resolved photograph reveals an asymmetrical structure of the heliopause. Neutral atoms in the intersteller medium can penetrate rather freely into the heliosphere. The structure is still speculative. Laboratory experiment of the interaction between a partially ionized supersonic plasma flow with a tilted magnetic field and an supersonic plasma flow simulating the 3-dimensional spreading solar wind plasma was also made to understand the effect of the neutral component of the LISM. The result shows an evident asymmetrical ionization of neutral gas along the up-wind and the down-wind. We found that the neutral component of LISM penetrating into the heliosphere was quite important because these neutrals could modify the populations of the plasma control the diffusion of LISM flow.