X-Ray Lasers as Probes of Plasma Parameters

General issues relevant to the probing of plasmas with backlighters are first discussed. It is shown that soft x-ray wavelengths (> 10 nm) can generally probe thicker plasmas than harder radiation (< 1 nm) if the plasma is hot (> 100 eV). Demonstration experiments are discussed where the transmission of x-ray lasers through other laser-heated solid targets have been used (i) to measure the rate of laser ablation of solid targets and (ii) to probe the opacity of a plasma material. It is shown that narrow bandwidth radiation, such as from an x-ray laser, offers the ability to probe much more optically thick plasmas than backlighters composed of moderate to wide bandwidth spectral lines.