Atomic spectroscopy with the shock tube

Spectroscopy of light atoms and ions and transition probability determinations using gas-driven shock tub

C2 and CN Emission in the Shock Tube

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70038/2/JCPSA6-27-6-1415-1.pd

X-ray spectral line coincidences between fluorine VIII (and IX) and transition metal lines

X-ray spectroscopy was performed in the 12 to 15 A region, recording L-shell lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Fe, Cr, Mn, and Ni L-spectra, and F VIII and F IX K-shell lines. Wavelengths were determined to accuracies of 1 to 3 mA and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions using 1.05 ..mu..m and 0.527 ..mu..m laser excitation with the KMS CHROMA laser

Preheat Effects on Microballoon Laser-Fusion Implosions

Nonequilibrium hydroburn simulations of early laser-driven compression experiments indicate that low energy photons from the vicinity of the ablation surface are preheating the microballoon-pushers, thereby severely limiting the compressions achieved (similar degradation may result from 1 to 4 percent energy deposition by superthermal electrons). This implies an 8- to 27-fold increase in the energy requirements for breakeven, unless radiative preheat can be drastically reduced by, say, the use of composite ablator-pushers. (auth

K-shell and L-shell plasma spectroscopy experiments

Detailed atomic level populations in high temperature and dense plasmas have become increasingly important in laser generated plasmas. Certain spectral line intensity ratios are density-dependent while others are temperature-dependent. Both can be used to extract information concerning population kinetics and ion level populations. In order to be useful these dependencies must be characterized by independent means. In laser produced plasmas this can be done via holographic interferometry for electron density determinations and via the slope of the H-like free-bound continuum of K-shell lines for electron temperature determinations. The characterization of density- and temperature-dependent L-shell lines can be accomplished in ionization balance experiments in which laser irradiance is varied on targets which contain both K-shell and L-shell emitters. The K-shell free-bound continua provide the local temperature determination while holographic interferometry yields density profile information, from which the temperature and density dependent L-shell lines can be characterized. This paper discusses these concepts

DIAGNOSTIC CHARACTERIZATION OF LASER-IRRADIATED DOT TARGETS

We have conducted a series of experiments at the KMS CHROMA facility using dot spectroscopy techniques to characterize uncertainties associated with spectral line ratio models commonly applied in determining electron temperatures and densities. Temperatures determined from the slope of the H-like free-bound continuum and densities via holographic interferometry, are compared to line ratio methods. Dot targets of (typically 100 μmD Mg or Al) are irradiated with 2 to 40 x 1013 W/cm2 of 0.53 μm light. Time and spatial gradients are resolved using 4 diagnostics: a 4-frame holographic interferometer, an x-ray streak crystal spectrograph with a spatial imaging slit, a framing crystal x-ray spectrometer, and a conventional space-resolved time-integrating crystal spectrograph used for survey and calibration purposes. Preliminary results indicate the ionization distribution of these laser produced plasmas is not steady-state which plays an important role in measuring the temperature and and density. Electron temperatures derived from line-ratio techniques, assuming steady state conditions, disagree dramatically from simultaneous measurements using the slope of the H-like continuum. Electron densities using He-like triplet to singlet line ratios also differ from densities measured interferometrically

HYDRODYNAMIC ASPECTS OF SELENIUM X-RAY LASER TARGETS

Recent experiments at KMS have been performed to investigate parameter variations of target component thickness, laser pulse duration and intensity, and one-sided vs two-sided irradiation in order to optimize the performance of the Livermore exploding foil selenium x-ray laser experiments. Preliminary experiments with selenium double foil targets were also conducted as a means of prolonging the duration and enlarging the spatial extent of the lasing conditions. Four-frame holographic interferometry was used in determining the time-dependence of densitiy profiles obtained by Abel inversion of the interferometric fringe field and comparisons were made to LASNEX code calculations