The role of radiative transfer in pulsed laser plasma-target interactions

The plasma generated when a 2024 aluminum target was irradiated with the beam from a cold-cathode electron-beam laser (CCEBL) has been investigated with spectroscopic techniques. The target was designed to form the end plate of a differentially pumped slit assembly attached to a visible-UV-VUV monochromator. A pinhole in the center of the plate permitted plasma radiation to enter the monochromator from the back side of the target. Calibration with tungsten, deuterium, and argon standards permitted quantitative plasma radiance measurements to be made in the region 115-600 nm using a range of diffraction gratings and photomultiplier tubes. The total radiant fluence observed (1 J/sq cm) was in reasonable agreement with the 1-1.2 J/sq cm of absorbed thermal fluence determined by independent thermal-coupling measurements. Photographic spectra of the plasma (100-620 nm) were recorded, and many features identified.