HARD X-RAY-EMISSION FROM INTENSE SHORT-PULSE LASER PLASMAS

Hard x-ray emission in the range of 100 keV has been measured from pla smas produced by irradiation of solid targets with ps laser pulses up to 7X10(17) W/cm(2). The experimental data obtained for oblique incide nce of p-polarized laser light at different illumination angles are co mpared to computer calculations, which include the processes of resona nce absorption and vacuum heating. The scaling of hard x-ray emission with varying laser flux is consistent with the theoretical model of br emsstrahlung emission of hot electrons. From this, together with an ab solute radiation dose measured with calibrated detectors, a transfer o f up to 50% of the incident laser energy to suprathermal (similar to 1 0...100 keV) electrons is estimated. (C) 1995 American Institute of Ph ysics.