High-Density Gas Jet Characterization for Laser-Plasma Interaction

To understand laser-plasma interaction and make use of plasma wakefield acceleration, we focus an intense laser pulse into a vacuum chamber and release high-density bursts of gas into the beam path. There exists a critical density of electrons beyond which an electromagnetic wave does not propagate. While the behavior of the plasma wave in the over- and under-dense regime is well established, densities in the vicinity of the critical value remain unexplored. In order to attain sufficiently high peak gas densities with short rise-time, we developed a method of injecting high-pressure gas from sub-millimeter gas jet nozzles, and designed and built a high-voltage pulse driver to control a state-of-the-art solenoid valve. We have demonstrated that near-critical density gas with sub-millisecond rise-times is producible, so it is a viable target for high-intensity laser wakefield acceleration experiments.