A time-resolved, in-chamber x-ray pinhole imager for Z.

We have commissioned a new time-resolved, x-ray imaging diagnostic for the Z facility. The primary intended application is for diagnosing the stagnation behavior of Magnetized Liner Inertial Fusion (MagLIF) and similar targets. We have a variety of imaging systems at Z, both time-integrated and time-resolved, that provide valuable x-ray imaging information, but no system at Z up to this time provides a combined high-resolution imaging with multi-frame time resolution; this new diagnostic, called TRICXI for Time Resolved In-Chamber X-ray Imager, is meant to provide time-resolved spatial imaging with high resolution. The multi-frame camera consists of a microchannel plate camera. A key component to achieving the design goals is to place the instrument inside the Z vacuum chamber within 2 m of the load, which necessitates a considerable amount of x-ray shielding as well as a specially designed, independent vacuum system. A demonstration of the imaging capability for a series of MagLIF shots is presented. Predictions are given for resolution and relative image irradiance to guide experimenters in choosing the desired configuration for their experiments.

GaAs x-ray detectors with sub-nanosecond temporal response.

Fast semiconductor radiation detectors operated in current mode provide a valuable diagnostic in pulsed power applications. Si detectors are common due to the availability of high-quality materials and mature fabrication processes, but they offer low absorption for hard x-rays above ∼10 keV. GaAs can provide increased hard x-ray absorption for the same detector volume due to a higher atomic number. GaAs photodiodes have been produced from epitaxial material grown at Sandia National Laboratories and fabricated at Sandia's microfabrication facility. These detectors have significantly higher hard x-ray absorption (>10× at 15 keV) and nearly identical temporal impulse response to similarly sized Si detectors of 0.5 ns full-width half maximum.