Inertial Fusion Sciences and Applications 2005
J.-C. Gauthier, et al.
J. Phys. IV France 133 (2006) 1173-1175
DOI: 10.1051/jp4:2006133239

Underdense radiation sources: Moving towards longer wavelengths

C.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. Kilkenny<sup>1

1</sup>  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

Abstract
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.

© EDP Sciences 2006