Continuum x-ray emission spectra from laser-produced plasmas at1016W/cm2

C${\mathrm{H}}_2$ and Al targets were irradiated at ${10}^{16}$ W/${\mathrm{cm}}^2$ with a focused Nd: glass laser to study the dependence of x-ray emission on laser-pulse parameters. Complementary optical diagnostics indicated that 60-80% of the incident laser energy was absorbed in the planar targets. X-ray intensities spanning eight orders of magnitude were measured from 1 to above 100 keV by the multiple absorption foil method. The spectral shapes for C${\mathrm{H}}_2$ targets were independent of pulse length for 21- and 250-psec pulses.