Temperature and density profiles of an MHD switch-on shock

An experimental study of the structure of MHD switch-on shock waves propagating into partially ionized hydrogen and helium plasmas is described. The variation of electron and ion temperatures through the shock front was studied as a function of the level of preionization. When the shock propagates into an almost fully ionized plasma, the electron temperature rises well above the ion temperature due to resistive heating of the electrons. At low preionization levels however, the ion temperature rises above the electron temperature. These results indicate that ion-neutral collisions can play a dominant role in the dissipation of energy in a shock wave. (author)