Characterization of laser heated gas jet targets for use as spectral emission sources

Laser irradiated submillimeter gas puff targets are being developed as a source of narrow linewidth visible and UV emission lines, to be used for time resolved Zeeman splitting measurements of intense laser driven magnetic fields [1].  Accurate temporal and spatial characterization of the temperature and density profiles in these plasmas is important to optimize the spectral lines of interest.  We have studied the generation of such low density plasmas both experimentally and with 2D hydrodynamic modelling.  In the experiments, the emission plasma is produced using a few hundred millijoule, 10 ns, 1.06 um, laser pulse focussed into the exit plane of 500 um diameter nozzle, with backing pressures of 1 to 8 bar. The starting neutral gas density profile for the nozzle is measured using Rayleigh scattering and modeled using 2 D fluid simulations for carbon dioxide and nitrogen gasses. This density profile is incorporated into the hydrodynamics code to calculate the heating and ionization as a function of position with respect to the nozzle tip for different gas densities and laser energies.  

1.  Santos, J. J., et al. "Laser-driven platform for generation and characterization of strong quasi-static magnetic fields." New Journal of Physics 17.8 (2015): 083051.