Donald Arthur Haynes

Diagnosis of High-Temperature Implosions Using Low- and High-Opacity Krypton Lines

High-temperature laser target implosions can be achieved by using relatively thin-shell targets, and they can be diagnosed by doping the fuel with krypton and measuring K-shell and L-shell lines. Electron temperatures of up to 5 keV at modest compressed densities (∼1–5 g/cm3) are predicted for such experiments, with ion temperatures peaking above 10 keV at the center. It is found that the profiles of low-opacity (optically thin) lines in the expected density range are dominated by the Doppler broadening and can provide a measurement of the ion temperature if spectrometers of spectral resolution Δλ/λ ≥ 1000 are used. For high-opacity lines, obtained with a higher krypton fill pressure, the measurement of the escape factor can yield the ρRof the compressed fuel. At higher densities, Stark broadening of low-opacity lines becomes important and can provide a density measurement, whereas lines of higher opacity can be used to estimate the extent of mixing.

Spectroscopic analysis of Ar‐doped laser‐driven implosions

In a series of experiments performed at the Laboratory for Laser Energetics plastic microballoons filled with DD and doped with small amounts of Ar were imploded using the Omega laser system. Time‐resolved K‐shell Ar spectra were simultaneously recorded using two spectrographs (SPEAXS and flat‐crystal). We focus on the analysis of the He‐β line and its associated Li‐like satellites. The density and temperature sensitivity of this composite spectral feature has been studied previously [R. C. Mancini et al., Rev. Sci. Instrum. 63, 5119 (1992)]. Here, we use it as a diagnostic. Modeling results take into account the built‐in density and temperature dependence characteristic of the level populations and broadening properties of these transitions; in addition, we also consider the effects of ion dynamics and opacity. To check the consistency of our analysis we include in the model the He‐γ and Ly‐β lines.

Plasma Induced Line Shifts: New Light on an Old Controversy

It appears that the theoretical lines shifted according to calculations provide substantially better fits than the theoretical line shapes which exclude line shifts. The differing principal quantum numbers associated with the Ly-β and He-γ lead to significantly differing shifts. Thus, the use of unshifted lines, shifted arbitrarily, en masse, would not lead to the same quality of fit observed when using the lineshapes shifted according to calculation.

Calculations and diagnostic applications of Stark-broadened absorption line profiles for the L-shell ions of argon

We calculated Stark-broadened absorption line profiles for n = 1 to n = 2 inner-shell transitions in the L -shell ions of Ar for electron number densities between 5 × 10 23 cm -3 and 5 × 10 24 cm -3 and for temperatures in the range 100–600 eV. These line profiles are used to calculate the frequency-dependent optical depth of hot, dense Ar plasmas. We also investigated the possibility of using Stark-broadened absorption line profiles for diagnostic applications.

Diagnosis of high-temperature implosions using low- and high-opacity Krypton lines

High-temperature laser target implosions can be achieved by using relatively thin-shell targets, and they can be. diagnosed by doping the fuel with krypton and measuring K-shell and L-shell lines. Electron temperatures of up to 5 keV at modest compressed densities ({approximately}1-5g/cm{sup 3}) are predicted for such experiments, with ion temperatures peaking above 10 keV at the center. It is found that the profiles of low-opacity (optically thin) lines in the expected density range are dominated by the Doppler broadening and can provide a measurement of the ion temperature if spectrometers of spectral resolution {Delta}{lambda}/{lambda} {ge} 1000 are used. For high-opacity lines, obtained with a higher krypton fill pressure, the measurement of the escape factor can yield the {rho}R of the compressed fuel. At higher densities, Stark broadening of low-opacity lines becomes important and can provide a density measurement, whereas lines of higher opacity can be used to estimate the extent of mixing.