Optical Thomson Scattering System for Sheared Flow Z-Pinch Experiments

Collective Thomson scattering is a powerful diagnostic technique that is capable of local measurements of various plasma parameters including electron density, electron temperature, ion temperature, and velocity. We have developed an optical Thomson scattering system on the shear flow Z-pinch machine FuZE at ZAP Energy inc. in Seattle Washington to measure at least the electron temperature and density. The system uses an Nd-YAG laser that is frequency-doubled to produce 8 J at 532 nm. Scattering is collected at an angle of 15° from 8 points within the plasma column and delivered by a fiber bundle to 2 spectrometers with gated CMOS cameras. One spectrometer records the high-frequency electron plasma wave (EPW) feature, while the other spectrometer records the low-frequency ion acoustic wave (IAW) feature. The recorded data can be compared to a theoretical scattering form factor to measure densities above 1 x 10 18 cm -3 , electron temperatures above 100 eV, and flow velocities above 20 km/s. Due to the high rep rate of the machine (1 shot every ~ 10 min) the time evolution of the plasma parameters over the long quiescent period of the pinch (~10 μs) can be studied by probing different times with the laser. Initial data will be presented.