Thomson Scattering Study of Collisional-Shock Heated Plasmas, Report No. 62

Thomson scattering was used to obtain eloctron temperature and density profiles in deuterium plasmas produced by strong collisional shock waves. The transverse shock speeds were 3 to 25 cm/ usec in 50 to 100 mTorr deuterium. Ruby laser light was incident at a right angle to the axis in the midpoint of the annular gap of an electromagnetically driven coaxial shock tube.and scattered 9 light was collected at 90 degrees. Plasma created by reflecting a strong shock from a dielectric wall was also studied. It is found that the plasma electron temperature (10-30 eV) is much less than the ion temperature (100-500 eV) as is predicted by theory for the early life of theplasma. Electron-lon Coulomb colllslonal temperature relaxation does not occur during the times of observation (3-4,AA sec). Electron heating in the plasma is caused primarily by Ohmic dissipation of currents in the shock structure and piston. Plasma densities (0.5-3.5x1016 cm-3)agree well with shock theory predictions. For gas ionizing shocks, good agreement with collisional theory is found for the electron temperature.