Experimental Study of the Structure of Plasma Shock Waves in a Fast θ Pinch

The density, temperature, and magnetic field structures of plasma shock fronts have been observed by means of scattered light, a magnetic probe, and emission spectroscopy. The shocks and initial hydrogen plasma were generated by capacitor discharges through a single-turn coil placed around a cylindrical quartz tube containing hydrogen. Electron velocity distributions (density and temperature) were obtained by analyzing the light scattered at 90° to the incident beam from a Q-switched ruby laser. The observed temperature structure was compared with that calculated from observed particle and current density by assuming local resistive dissipation due to binary electron-ion collisions. Agreement was good in two cases, but, in a case characterized by lower initial ωceτ(0.6), the velocity distribution developed enhanced wings and enhanced heating occured. These effects indicate a diffusion of high-energy electrons from the hot, downstream region. Ion temperatures, obtained from Doppler broadening of a carbon line, are consistent with compressional heating and thermal conduction across field lines.