Improving Dante flux measurements with parameterized gold M-band spectral information from NIF experiments*

Dante is a diagnostic used to measure the x-ray drive inside a hohlraum at the NIF. In indirect-drive ICF experiments, a low-Z shell of a small capsule filled with DT is heated and ablated by the x-ray drive, pushing the capsule inward through a "rocket effect." The x-ray drive is generated with laser beams depositing their energy in the non-LTE high-Z plasma created near the hohlraum's interior Au wall. Most of this energy is transferred via conduction to the wall, which becomes heated to a few hundred eV, producing the blackbody radiation to drive the capsule. The non-LTE plasma also emits Au M-band photons, which penetrate deeper into the capsule and can preheat the fuel, thereby significantly reducing the fusion yield. It is essential to measure the time history and spectral shape of the x-ray flux to understand the preheat and mitigate it by doping the capsule shell with a mid-Z element to absorb the Au M-band photons. The unfold can be improved with Au M-band information recorded from the high-resolution Virgil spectrometer. We approximate the recorded spectrum with two Gaussians to use it in the unfold. The x-ray flux and voltages will be presented and compared with the standard Dante unfold. *Supported by DOE/NNSA. This work performed under the auspices of the U.S. DOE by LLNL under Contract No. DE-AC52-07NA27344. DISTRIBUTION A: Approved for public release. Distribution is unlimited.