Diagnostics and Modeling of Gas Puff Target Laser Plasma Radiation Source

AbstraktAbstract

Here we present a study of XUV emission characteristics of nitrogen plasma induced by infrared laser pulse (800 mJ / 7 ns) focused into a gas puff target. Spatial distribution of nitrogen density was determined by EUV radiography at the wavelength 13.5 nm. We used Gaussian function to approximate the cross-section of the gas puff target in the direction perpendicular to the axis of the nozzle. The value of target mass density was estimated to be 3.7·10-4 g/cm3 at the distance z = 0.5mm from the nozzle and 4.9·10-4 g/cm3 at z = 0.25 mm from the nozzle. The resulting density profile at the focal region and measured time dependences of laser power were introduced as input data to 2D RMHD (Radiation-Magneto-Hydro-Dynamic) code Z* (EPPRA s.a.s, France). Spatial developments of nitrogen plasma quantities were modeled. The evaluated electron temperature at the center of gas puff target exceeded the value Te ~ 34 eV. The related peak value of emitted energy density, in the wavelength region 2.8766 - 2.8867 nm approached the value Qeuv ~ 0.3 J/cm3. The evaluated spatial distributions of emitted energy were compared with the experimental data obtained with a compact laser-based XUV source (Laser Laboratory Göttingen e.V., Germany).

Here we present a study of XUV emission characteristics of nitrogen plasma induced by infrared laser pulse (800 mJ / 7 ns) focused into a gas puff target. Spatial distribution of nitrogen density was determined by EUV radiography at the wavelength 13.5 nm. We used Gaussian function to approximate the cross-section of the gas puff target in the direction perpendicular to the axis of the nozzle. The value of target mass density was estimated to be 3.7·10-4 g/cm3 at the distance z = 0.5mm from the nozzle and 4.9·10-4 g/cm3 at z = 0.25 mm from the nozzle. The resulting density profile at the focal region and measured time dependences of laser power were introduced as input data to 2D RMHD (Radiation-Magneto-Hydro-Dynamic) code Z* (EPPRA s.a.s, France). Spatial developments of nitrogen plasma quantities were modeled. The evaluated electron temperature at the center of gas puff target exceeded the value Te ~ 34 eV. The related peak value of emitted energy density, in the wavelength region 2.8766 - 2.8867 nm approached the value Qeuv ~ 0.3 J/cm3. The evaluated spatial distributions of emitted energy were compared with the experimental data obtained with a compact laser-based XUV source (Laser Laboratory Göttingen e.V., Germany).