Search

The development of a new time-resolved x-ray spectrometer is reported in which a free-standing x-ray transmission grating is coupled to a soft x-ray streak camera. The instrument measures continuous x-ray spectra with 20-psec temporal resolution and moderate spectral resolution (Δλ ≥ 1 Å) over a broad spectral range (0.1–5 keV) with high sensitivity and large information recording capacity. Its capabilities are well suited to investigation of laser-generated plasmas, and they nicely complement the characteristics of other time-resolved spectroscopic techniques presently in use. The transmission grating spectrometer has been used on a variety of laser-plasma experiments. We report the first measurements of the temporal variation of continuous low-energy x-ray spectra from laser-irradiated disk targets.

X-ray production in the region ˜ 13 nm from laser-produced plasmas has been investigated as a source for projection x-ray lithography. The dependence of x-ray conversion efficiency on target material, intensity, and pulse length has been studied by using a 0.53-µm laser with a maximum of 0.3 J. A conversion efficiency of 1% into a 0.3-nm bandwidth has been demonstrated for Sn targets at intensities of ˜ 10^11 W/cm^2 by using a 7.5-ns pulse. Intensity scaling suggests that laser spot size and two-dimensional expansion are important for optimizing x-ray production at these low-irradiation intensities.