DESC0022935

The problem being addressed: The plasmas generated by intense lasers are of great interest for fundamental physics and for practical reasons that include the generation of high energy photon and particle beams, industrial processes such as extreme ultraviolet lithography, and fusion energy. These plasmas have complex dynamics, of which time resolved velocity distribution can reveal important attributes, including the initial inward motion of the plasma driven by the intense laser pulse, the lateral transport of energy, and the subsequent plasma expansion. Several types of instruments have been developed to measure the plasma velocity. One of these instruments is the VISAR (velocity interferometer system for any reflector). However, as its time resolution is typically limited from nanoseconds to tens of picoseconds depending on the detectors used, it is challenging to map the velocity in the transverse direction with high temporal resolution. How we propose to address the problem/ situation in Phase I: XUV Lasers, in collaboration with Colorado State University, proposes to develop and demonstrate an instrument that will be able to map the velocity of plasmas generated by ultra-intense ultrashort pulse laser in two dimensions (2-D) with a spatial resolution of a few micrometers and femtosecond time resolution using a single spectrometer. In this instrument the Doppler shift of a second harmonic probe laser pulse of ~ 50 fs femtosecond duration reflected by the plasma will be measured simultaneously at many plasma locations using a high magnification microscope objective and a custom designed grating spectrometer. The time evolution of the velocity will be measured by varying the delay between the laser pulse that drives the plasma and the probe pulse. The necessary software to acquire, display, and convert the data into a velocity map will be developed. The instrument will be designed in Phase I and a proof-of-principle experiment will be conducted to demonstrate the concept. Commercial applications and other benefits: This new plasma diagnostics instrument could be of significant use in many ultra-intense laser-matter interaction experiments conducted at different research and laser facilities, including those that are part of LaserNetUS, and for the laser-created plasmas that are of industrial interest for extreme ultraviolet lithography.