Abstract

Picosecond K_α x-ray pulses are produced at a repetition rate of 300 Hz from an x-ray diode via laser-driven photo emission by picosecond ultraviolet laser pulses. Deep UV radiation is used to maximize the quantum yield from photoemission from an aluminum cathode. The laser system is based on ArF excimer amplification of picosecond seed pulses of 193 nm radiation generated by sum frequency generation in BBO. Picosecond pulses from a cw mode-locked Nd:YLF laser are frequency doubled to pump a dye laser at 728 nm and also used to seed a Nd:YLF regenerative amplifier. Non-linear upconversion in a series of BBO crystals provides 193 nm seed pulses of duration less than 10 ps with energies of 1–3 μj at a repetition rate of 300 Hz. An ArF excimer discharge is used to amplify these pulses to 1–2 mJ energies. The intense picosecond UV radiation illuminates an aluminum photocathode to produce electron bunches that are accelerated across a diode gap of 1 cm and 75 kV to impact a copper target and generate characteristic hard x-ray pulses at 1.5 Å with a duration of less than 30 ps. The spatial and temporal characteristics of the x-ray source as well as results from time-resolved x-ray studies of solid surfaces will be presented.

© 1992 Optical Society of America