Abstract
This paper describes the design considerations for Target Diffraction In-Situ (TARDIS), an x-ray diffraction diagnostic
at the National Ignition Facility. A crystal sample is ramp-compressed to peak pressures between 10 and 30 Mbar and,
during a pressure hold period, is probed with quasi-monochromatic x-rays emanating from a backlighter source foil. The
crystal spectrography diffraction lines are recorded onto image plates. The crystal sample, filter, and image plates are
packaged into one assembly, allowing for accurate and repeatable target to image plate registration. Unconverted laser
light impinges upon the device, generating debris, the effects of which have been mitigated. Dimpled blast shields, high
strength steel alloy, and high-z tungsten are used to shield and protect the image plates. A tapered opening was designed
to provide adequate thickness of shielding materials without blocking the drive beams or x-ray source from reaching the
crystal target. The high strength steel unit serves as a mount for the crystal target and x-ray source foil. A tungsten body
contains the imaging components. Inside this sub-assembly, there are three image plates: a 160 degree field of view
curved plate directly opposite the target opening and two flat plates for the top and bottom. A polycarbonate frame,
coated with the appropriate filter material and embedded with registration features for image plate location, is inserted
into the diagnostic body. The target assembly is metrologized and then the diagnostic assembly is attached.
