Effective collision cross section of xenon plasma debris in argon buffer gas

Abstract

Mitigation of fast debris and soft x-rays generated from laser-produced xenon plasmas were studied in an argon buffer gas in laser intensities of 109–1011 W cm−2 using a cryogenic drum target. Considerable mitigation of debris was confirmed by measurements of material sputtering. From the experimental results, an attenuation parameter of sputtering by the debris and an absorption cross section of soft x-rays at 13.5 nm σ2(13.5 nm) were derived to be 2.2 × 10−20 m2 and 1.8 × 10−22 m2, respectively. Moreover, is concluded to be equivalent to the effective collision cross section σ1 of a debris particle at kinetic energy of 1–4 keV. Sufficient debris mitigation can be obtained together with low soft x-ray absorption (less than 10%). These parameters provide a useful design tool for realizing a practical soft x-ray source because they predict the effect of the buffer gas well.