Prepulse-enhanced narrow bandwidth soft x-ray emission from a low debris, subnanosecond, laser plasma source

Soft x-ray emission from 170 ps laser-produced plasmas formed on cerium-doped borosilicate glasses has been recorded in the 7–17 nm region using a 2 m grazing incidence vacuum spectrograph. Broadband spectra have been recorded on photographic plates, while intensity comparisons have been made using an absolutely calibrated, extreme ultraviolet sensitive photodiode. The use of a laser prepulse to prime the target has been seen to enhance the emission with the maximum flux produced at an interpulse delay of 5.1 ns. The peak conversion efficiency is found to be 4.8%±1.5% into 3% bandwidth, centered at 8.8 nm. In addition, the level of debris emitted by the target is greatly reduced by comparison with solid metallic targets.