Pulsed soft x‐ray source for laser‐plasma diagnostic calibrations

Improvement in laser‐plasma analysis makes it necessary to perform accurate calibration in the soft x‐ray range. For this purpose we have modified a plasma focus device (27 kJ, 40 kV, and 400 kA) in order to enhance its soft x‐ray emission: A hollow anode is used to prevent hard x‐ray bremsstrahlung emission, and a lot of filling gases are chosen for their characteristic lines in the keV and sub‐keV range (Ne, Ar, O, N, and CH4). These emissions have been absolutely measured with an x‐ray bolometer and can be used directly or indirectly (in the fluorescent mode: Mg Kα at 1.254 keV) for x‐ray calibration of various diagnostics. Some detector calibrations in pulsed regime (10 ns) are presented [films, solid state Si doped p‐intrinsic‐n (P I N) diodes, and charge‐coupled devices (CCD) arrays.]