High powered, short-pulsed laser facility for hard x-ray and hot electron generation.

摘要

For decades, pulsed high-powered laser-produced plasmas have been used as a tool for probing solid media to observe transient phenomena through shadowgraphy. This has allowed time-resolved studies of energetic reactions like shock wave propagation within these solids and has provided insight into these reactions on time scales on the order of nanoseconds to as low as 100's of picoseconds. Shadowgrams produced by these techniques are limited to materials exhibiting little or no absorption of the probing radiation. Therefore, x-rays generated by laser-produced plasmas need to be both high in flux and photon energy (1 keV and up) to propagate through dense materials. This makes it necessary for long-pulse lasers to produce high-energy laser pulses in order to make sufficient amounts of the hard x-rays required for probing dense materials effectively.; The development of short-pulse (t ≤ 100 fs) high peak power laser systems which can generate high peak intensities (>1018 W/cm 2) on target with modest amounts of energy (1J) provides a solution to these material limitations. Plasmas produced by these lasers generate extremely hot electrons and hard x-rays. This permits the investigation of higher density materials than before since the absorption is significantly lower for high energy photons. In addition, the hard x-ray emission of short-pulse laser plasmas is on the order of 1 ps duration or less, thus making higher temporal resolution possible.; In this dissertation, spectral measurements of short-pulse laser-produced plasmas will be discussed along with applications of these plasmas for probing transient phenomena using backlighting and Laue diffraction techniques. In addition, CREOL's Cr:LiSAF based, Terawatt laser plasma facility will be described.