Absolute spectral distribution of soft X-ray emission from laser produced gold plasma

Quantitative measurement of spectral distribution of soft X-ray emission from laser produced plasmas and estimation of X-ray conversion efficiency are reported. The X-ray emission from planar gold target irradiated by an Nd:glass laser was recorded using a high resolution transmission grating spectrograph. Spectral distribution of X-ray intensity was derived using calibrated film data and a deconvolution procedure to account for contribution of higher diffraction orders. Results of conversion efficiency per unit solid angle, at a laser intensity of /spl sim/4/spl times/10/sup 12/ W/cm/sup 2/ (/spl lambda//sub L/ = 1.054 /spl mu/m), for 10< /spl lambda/ <80 /spl Aring/ and in the water window spectral region (23< /spl lambda/< 44 /spl Aring/) are presented. A three-fold increase in conversion efficiency was observed for second harmonic laser irradiation (/spl lambda//sub L/ = 0.527 /spl mu/m) at an intensity of 8/spl times/10/sup 12/ W/cm/sup 2/.