A technique for diagnosing the core temperature ${\mathit{kT}}_{\mathrm{core}}$ and shell areal density ρ${\mathit{R}}_{\mathrm{shell}}$ of laser-imploded targets by measurement of the space-resolved, continuum x-ray emission is described in this work. An estimate of ${\mathit{kT}}_{\mathrm{core}}$ 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 ρ${\mathit{R}}_{\mathrm{shell}}$. 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-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 (<100 mg/${\mathrm{cm}}^2$), space-resolved continuum-absorption spectroscopy should be applicable to the diagnosis of higher shell-areal-density implosions (>100 mg/${\mathrm{cm}}^2$). 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 (∼1 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 ${\mathit{kT}}_{\mathrm{core}}$ and ρ${\mathit{R}}_{\mathrm{shell}}$ to be obtained.

• Received 29 November 1993

DOI:https://doi.org/10.1103/PhysRevE.49.4381