X-ray emission from KrF laser-produced Al plasmas

A high power (200 J, 50 ns) 249-nm KrF laser has been focused onto solid Al targets in vacuum at a peak irradiance of 3×1013 W cm−2. High-temperature (>200 eV) plasmas are produced and x-ray measurements show intense emission of the resonance spectra of Al XII and Al XIII in the wavelength range 0.6–0.8 nm. Absolute x-ray intensity measurements indicate a maximum source brightness of 1.1×1017 erg cm−2 s−1 sterad−1 in Δν/ν=10−3 (Al XII, 1 1S0–2 1P1, 0.776 nm) and a conversion efficiency from laser power to x-ray power of 0.2% for 1.5 keV