Scaling of x-ray emission and ion velocity in laser produced Cu plasmas

The x-ray emission from slab targets of copper irradiated by Nd:glass laser (1.054 µm, 5 and 15 ns) at intensities between 10¹² and 10¹¹W/cm² has been studied. The x-ray emissions were monitored with the help of high quantum efficiency x-ray silicon photo diodes and vacuum photo diodes, all covered with aluminium filters of different thickness. The x-ray intensity vs the laser intensity has a scaling factor of (1.2–1.92). The relative x-ray conversion efficiency follows an empirical relationship which is in close agreement with the one reported by Babonneau et al. The ion velocities were monitored using Langmuir probes placed at different angles and radial distances from the target position. The variation of the ion velocity with the laser intensity follows a scaling of the form Φ ^β where β ～0.22 which is in good agreement with the reported scaling factor values. The results on the x-ray emission from Cu plasma are reported.