Diagnosis of laser-target implosions by space-resolved continuum absorption x-ray spectroscopy
- Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)
A technique for diagnosing the core temperature [ital kT][sub core] and shell areal density [rho][ital R][sub shell] of laser-imploded targets by measurement of the space-resolved, continuum x-ray emission is described in this work. An estimate of [ital kT][sub core] is obtained from a fit to the space-resolved core x-ray spectrum. Observation of absorption by the cooler surrounding shell material is used to estimate [rho][ital R][sub shell]. For the x-ray emission from the core to be detected, its flux density must exceed that of the time-integrated emission from the ablation layer, making this technique particularly applicable to diagnosis of targets with low-[ital Z] ablators. In contrast to techniques that depend upon measurements of the reaction products (e.g., knock-ons, secondary-reaction products), which are limited to low shell-areal-density implosions ([lt]100 mg/cm[sup 2]), space-resolved continuum-absorption spectroscopy should be applicable to the diagnosis of higher shell-areal-density implosions ([gt]100 mg/cm[sup 2]). This technique has been successfully applied to the diagnosis of evacuated, polymer-coated, deuterated polystyrene (CD) shell implosions (surrogate-cryogenic implosions) performed with the University of Rochester's, 24-beam uv, OMEGA laser system. Space-resolved spectra of the target x-ray emission ([similar to]1 to [similar to]6 keV) were obtained with a grazing-incidence reflection microscope, dispersed by a transmission grating. Both a high-energy tail and absorption at low energies were observed in the x-ray spectra allowing estimates of [ital kT][sub core] and [rho][ital R][sub shell] to be obtained.
- DOE Contract Number:
- FC03-92SF19460
- OSTI ID:
- 7206564
- Journal Information:
- Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States), Vol. 49:5; ISSN 1063-651X
- Country of Publication:
- United States
- Language:
- English
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LASER IMPLOSIONS
PLASMA DIAGNOSTICS
LASER-PRODUCED PLASMA
X-RAY SPECTRA
ABSORPTION SPECTROSCOPY
PLASMA HEATING
X RADIATION
ELECTROMAGNETIC RADIATION
HEATING
IMPLOSIONS
IONIZING RADIATIONS
PLASMA
RADIATIONS
SPECTRA
SPECTROSCOPY
700320* - Plasma Diagnostic Techniques & Instrumentation- (1992-)
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