A pseudo-Wolter microscope for core implosion imaging at the National Ignition Facility.

Inertial confinement fusion experiments at the National Ignition Facility (NIF) use an X-ray drive to converge a ~1mm radius spherical shell ~30x its original radius. Typical core diameters range from 50 µm, in cryogenic layered implosions, to 100 µm in gas filled implosions. The x-ray emission is peaked between 8 and 10keV. Current X-ray imaging at NIF has a spatial resolution element around 10 µm which is insufficient to resolve structure the core. Low resolution and poor signal to noise ratio limits the observable features during the later stages of the implosion.

Using grazing incidence toroidal mirrors in a pseudo-Wolter configuration, a focusing, 3-color, multi-channel x-ray microscope is in design for NIF. The system will have 15x magnification, a sub-5 µm full width at half maximum spatial resolution and a collection efficiency ~10^-7 sr. It will be coupled to a state of the art single line of sight detector (SLOS) which has a temporal resolution ~50 ps. We will describe this pseudo-Wolter microscope whose high performances will give a time-resolved observation of the source shape features along with a plasma temperature and density measurements.

Release # LLNL-ABS-753682.

Prepared by LLNL under Contract DE-AC52-07NA27344