Electron Plasma Wave Thomson Scattering on Laboratory Plasma Jets*

Thomson scattering in the collective regime can be used for plasma electron density measurements by using the electron plasma wave feature. Such measurements have been performed on plasma jets created from a 15 μm thick radial Al foil load on COBRA, a 1 MA pulsed power machine. The scattering from the electron plasma wave was used to measure the electron density and temperature inside and outside of a plasma jet created by the radial foil. The laser used for these measurements had a maximum energy of 10 J at 526.5 nm. Previous experiments observing the stronger ion acoustic wave feature have shown that the full laser energy significantly heats the estimated 5×10¹⁸ cm^-3 jet by inverse bremsstrahlung from 20 eV to 90 eV. By using scattering from the electron plasma wave in tandem with scattering from the ion acoustic wave a more accurate picture of the plasma jet and its heating can be achieved.  Results will be presented comparing time resolved ion acoustic wave features with time gated electron plasma wave features.