Coherent and incoherent XUV emission in helium and neon, laser-driven plasmas

The authors present results of measurements of high-order harmonic generation and XUV spontaneous emission in helium and neon plasmas excited by a short pulse laser at intensities between 10/sup 14/ and 5*10/sup 17/ W/cm/sup 2/. They compare the observed behavior of the harmonics with recent single atom calculations in helium. A wavelength dependence to the efficiency of harmonic generation that has not been previously reported is observed. Line emission from excited state transitions in Ne/sup 7+/ in a short pulse laser-driven plasma is also observed. In particular, strong emission and a rapid recombination rate for the 9.8-nm (3d-2p) transition that is a possible candidate for a recombination-pumped X-ray laser is shown.<
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