Analysis and comparison of x-ray image and x-ray burst features of high intensity laser beam jets interaction experiments on the leopard laser at UNR

Results of Ar gas-puff experiments performed on the high power Leopard laser at UNR are presented. The Leopard laser operated in two regimes: 350 fs, 40 TW pulse, or 0.8 ns, 25 GW pulse (pulse contrast from 10^-5 to 10^-7). Laser wavelength was 1.057 μm. The supersonic linear nozzle was compared with cylindrical tube sub-sonic nozzle. Flux density of laser radiation in focal spot was from 3×10¹⁶ W/cm² (ns piulse) up to 2×10¹⁹ W/cm² (fs pulse). The laser beam axis was positioned either along the jet plane or orthogonal to it at a distance of 1 mm from the nozzle output. Diagnostics included two sets of filtered Si-diodes (covered region from 1 to 55 keV), x-ray pinhole cameras, x-ray spectrometers, and Faraday cups. Specifically, x-ray images and structure of x-ray bursts are investigated and compared as a function of the orientation of the laser beam to the linear or cylindrical gas jet and laser pulse duration. The importance of analysis and comparison of x-ray image and x-ray burst features for a better understanding the mechanisms of the laser energy to x-ray conversion efficiency and future research directions are discussed.