STUDY OF 2ND-HARMONIC EMISSIONS FOR CHARACTERIZATION OF LASER-PLASMA X-RAY SOURCES

An investigation of second harmonic (SH) and X-ray emissions from Al p lasmas produced by 3-ns, 1.064-mu m laser pulses at 10(14) W/cm(2) is reported. The SH and X-ray yields are strongly correlated as a functio n of the target position with respect to the laser beam focus. The SH originates from the underdense coronal plasma and has a filamentary so urce, while the X-ray source is uniform. The results suggest that, alt hough the X-ray emission is significantly enhanced by the filamentatio n of the laser light in the corona, there is a smoothing effect in the energy transport process toward the overdense region.