SOFT-X-RAY OUTPUT FROM A LASER-PRODUCED PLASMA

X-rays in the 0.5-1.6 keV photon energy range, useful for debris-free damage testing Of optical components, are produced efficiently by a laser-produced plasma. Energies exceeding 1 kJ in three beams from the NRL Pharos III laser irradiate a copper target to produce, L-shell x-rays from plasma ions. A near-isotropic x-ray fluence of typically 5 cal/cm2 at 1 cm from the source is deduced from measurements with filtered Si-PIN and biplanar vacuum diodes. The corresponding conversion efficiency of laser to x-ray energy is typically 11%.