Soft x-ray emissions from laser plasma of cryogenic mixture targets

Abstract

Soft x-ray spectral radiation from Xe–CO2 mixture cryogenic targets with a Xe mole fraction of 0% (pure CO2) to 100% (pure Xe) irradiated by a 1 μm pulse laser at a laser intensity IL of 0.3–1.0×1012 W/cm2 has been observed. The x-ray conversion efficiency per Xe mole fraction was found to have maximum values at the Xe fractions of 10% for IL=6.0×1011 W/cm2 and 5% for IL=1.2×1012 W/cm2, which were about five and ten times as large as that in a pure Xe target, respectively. The x-ray conversion efficiencies in the cryogenic mixture targets at Xe fractions of 10%–40% were about 1.3 %/sr/nm for λ=10.8 nm and IL=1012 W/cm2, which was as high as that in a pure Xe cryogenic target. The physical mechanism behind this enhanced emission is discussed.