THOMSON SCATTERING MEASUREMENTS OF MAST PLASMAS.

Measurements of Thomson scattering from the plasma electrons were created by high speed shock waves in a magnetic annular shock tube MAST used to determine the electron density behind the shock waves, and some preliminary measurements of the electron velocity distribution. A Q-switch ruby laser furnished the light beam which was scattered by the plasma electrons. A rotating quartz prism furnished the Q-switching of the optical cavity for the ruby laser, and rather long Q-switched pulses were obtained between 10 to the -7th power and 10 to the -6th power sec duration. The power level during the Q-switched pulse was between 30 and 100 megawatts. Rayleigh scattering from an air sample at various pressures was used to calibrate the power output of the laser and gave a simultaneous measure of the laser output power for all of the tests, while the Thomson scattering was being measured. The measurements of the electron density using the Thomson scattering and the plasma continuum intensities agreed within the scatter of the data. The electron temperature measurements obtained with the Thomson scattering showed that the electron temperature increased with increasing shock speed for a given initial condition. Author