A novel hohlraum with ultrathin depleted-uranium-nitride coating layer for low hard x-ray emission and high radiation temperature

TL;DR

This study introduces a uranium nitride coating on depleted uranium hohlraums that reduces hard x-ray emission and enhances radiation temperature, improving the uniformity of x-ray fields for ignition applications.

Contribution

The paper presents a novel UN coating on depleted uranium hohlraums that effectively prevents oxidation and optimizes x-ray emission characteristics, a first in this application.

Findings

Hard x-ray fraction decreased by 61%

Total x-ray flux increased by 5%

Enhanced uniformity of x-ray field observed

Abstract

An ultra-thin layer of uranium nitrides (UN) has been coated on the inner surface of the depleted uranium hohlraum (DUH), which has been proved by our experiment can prevent the oxidization of Uranium (U) effectively. Comparative experiments between the novel depleted uranium hohlraum and pure golden (Au) hohlraum are implemented on Shenguang III prototype laser facility. Under the laser intensity of 6*10^14 W/cm2, we observe that, the hard x-ray (> 1.8 keV) fraction of this uranium hohlraum decreases by 61% and the peak intensity of total x-ray flux (0.1 keV ~ 5.0 keV) increases by 5%. Radiation hydrodynamic code LARED is used to interpret the above observations. Our result for the first time indicates the advantage of the UN-coated DUH in generating the uniform x-ray field with a quasi Planckian spectrum and thus has important implications in optimizing the ignition hohlraum design.