Spectral Response Measurement Of The National Ignition Facility Kirkpatrick-Baez Microscope

The multi-channel Kirkpatrick-Baez microscope (KBM), currently in use at the National Ignition Facility (NIF), uses grazing incidence multilayer crystals to focus x-rays to form an image. This diagnostic produces four images with a similar to 11x magnification, with a designed energy response of 10.2 +/- 1.5 keV at <10 mu m resolution over a 300 mu m x 300 mu m field of view. The KBM has been designed to image the imploded core of inertial confinement fusion (ICF) experiments, which have diameters ranging over 50-100 mu m and broadband emission. The self-emission spectrum is broadband and peaked at similar to 10 keV.We present a new calibration of the KBM using a molybdenum (W, Z = 42) x-ray microfocus source to measure the spectral response of the instrument over its field of view. Our results measure the variation and dependence on the coalignment of the four imaging channels, relating the region of best resolution and optimal spectral response.