Recent advances and results from the solid radiochemistry nuclear diagnostic at the National Ignition Facility

Abstract

The solid debris collection capability at the National Ignition Facility has been expanded to include a third line-of-sight assembly. The solid radiochemistry nuclear diagnostic measurement of the ratio of gold isotopes is dependent on the efficient collection of neutron-activated hohlraum debris by passive metal disks. The collection of target debris at this new location is more reliable in comparison to the historic locations, and it appears to be independent of collector surface ablation.

An effort to enhance the threshold contrast index of gas Cherenkov detectors

“…Because the energy of fusion gamma rays is higher than that of most secondary gamma rays (less than 12 MeV generally), it is a very natural choice to exclude interference from secondary gamma rays if considering the energy threshold response characteristic of the Cherenkov mechanism. Therefore, gas Cherenkov detectors (GCDs) with 12 MeV threshold have been designed for detecting fusion gamma rays, and some super GCDs with higher Cherenkov sensitivity or lower Cherenkov threshold energy have also been widely studied and developed in the past few decades [4][5][6][7][8][9][10][11][12][13][14][15]. Those GCDs have also been successfully applied for diagnosing bang time, reaction history and ablator areal density measurements in the OMEGA laser-based inertial confinement fusion facility (ICF) and the national ignition facility (NIF).…”