Hard x‐ray diagnostics for laser fusion plasmas analysis

Two diagnostics for the study of hard x‐ray emission produced by plasmas during inertial confinement fusion experiments, are described: (i) a hard x‐ray spectrometer to measure the high‐energy tail of the spectrum, with eight spectral bands in the 50–400‐keV range, by fluorescence and simple filter techniques; (ii) a time‐integrated pinhole imaging device using a microchannel plate converter tube and a 7.5‐μm‐thick tantalum photocathode adjusted for a mean spectral sensitivity around 200 keV. Adjustment and test of these diagnostics have been performed with a pulsed hard x‐ray generator using a plasma focus device. Absolute calibration of the spectrometer detectors (scintillator Photomultiplier) was obtained on an x‐ray tube with fluorescent emission lines (10–100 keV) and with a cobalt radioactive source at 1.23 MeV.