Initial characterization of a dynamic hohlraum radiation source tailored for high-temperature opacity measurements at an 8-MA facility

Abstract

This paper reports some important properties of a dynamic hohlraum radiation source intended to study the high-temperature opacity of medium- Z atoms. The time-resolved axial radiation power in two x-ray diodes gives the time-evolution of an equivalent black-body temperature that peaks at ∼260 eV at stagnation. Time-gated framing pinhole images show that the source comprises an intense high-temperature core that lasts for ∼2 ns preceded by a 10-ns-long lower-temperature implosion phase that emits mostly softer x rays. Combining pinhole images with soft x-ray power gives a time-resolved brightness radiation temperature that reaches 130 eV. Thus, the lower-temperature source could ionize an opacity sample, then the intense high-temperature radiation pulse could measure its opacity. Likewise, the time-integrated spectrum measured with a spherically bent crystal spectrometer is compatible with multiple blackbodies with different temperatures, from 176 to 185 eV. These characterizations suggest that this dynamic hohlraum can be used for high-temperature opacity measurements.