Thomson Scattering Measurements of Magnetic Annular Shock Tube Plasmas

Measurements of Thomson scattering from the plasma electrons created by high speed shock waves in a magnetic annular shock tube have been used to determine the electron density behind shock waves and some preliminary measurements of the electron velocity distribution. A Q-switched 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 10−7 and 10−6 sec duration). The power level during the Q-switched pulse was between 30 and 100 mW. Rayleigh scattering from an air sample at various pressures was used to calibrate the power output of the laser and gave for all of the tests a simultaneous measure of the laser output power, 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.