J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 1173-1175
Underdense radiation sources: Moving towards longer wavelengthsC.A. Back1, J.F. Seely2, J.L. Weaver2, U. Feldman3, R. Tommasini4, S.G. Glendinning4, H.-K. Chung4, M. Rosen4, R.W. Lee4, H.A. Scott4, M. Tillack5 and J.D. Kilkenny1
1 General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
2 Naval Research Laboratory, 4555 Overlook Drive, Washington, DC 20375, USA
3 Artep Inc., 2922 Excelsior Ct., Ellicott City, MD 21042, USA
4 Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94551, USA
5 U. C. San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. Eventually we hope to extend our studies to x-ray production in the EUV range.
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