Optical transmission of glass for the National Ignition Facility near backscatter imagers under x-ray exposure.

In experiments at the National Ignition Facility (NIF), the near backscatter imager materials need to maintain high optical transmission while exposed to hohlraum generated x rays. Glass plates are incorporated in the design to protect the optical scattering plates from x-ray damage. Radiation environments spanning those expected on NIF have been produced at the Omega Laser Facility by symmetric laser illumination of 1 mm sized gold spheres. The time-dependent ultraviolet transmission of sample glass plates was measured. The data are interpreted with a free electron absorption model. Combined with the simulations of the hohlraum x-ray emission, this model is used to predict the transmission of the glass plates on the NIF. We predict that the plates should perform adequately up to the peak of the laser pulse.

[1]  Martin,et al.  Space-time observation of an electron gas in SiO2. , 1994, Physical review letters.

[2]  Steven W. Haan,et al.  A comparison of three-dimensional multimode hydrodynamic instability growth on various National Ignition Facility capsule designs with HYDRA simulations , 1998 .

[3]  Peter A. Amendt,et al.  Update on design simulations for NIF ignition targets, and the rollup of all specifications into an error budget , 2007 .

[4]  Arnold,et al.  Theory of laser-induced free-electron heating and impact ionization in wide-band-gap solids. , 1992, Physical review. B, Condensed matter.

[5]  Edward I. Moses,et al.  The National Ignition Facility: Laser Performance and First Experiments , 2005 .

[6]  F. B. McLean,et al.  Electron-hole pair-creation energy in SiO2 , 1975 .

[7]  Jiang Hong-bing,et al.  Diagnose Parameters of Plasma Induced by Femtosecond Laser Pulse in Quartz and Glasses , 2006 .

[8]  Jochen Schein,et al.  X-ray conversion efficiency of high-Z hohlraum wall materials for indirect drive ignition , 2008 .

[9]  R. Kirkwood,et al.  Full-aperture backscatter measurements on the National Ignition Facility , 2004 .

[10]  F. Goulding,et al.  Semiconductor Radiation Detectors , 1970, Science.

[11]  C. Sorce,et al.  Soft x-ray power diagnostic improvements at the Omega Laser Facility , 2006 .

[12]  J. E. Miller,et al.  X-Ray Preheating of Window Materials in Direct-Drive Shock-Wave Timing Experiments , 2006 .

[13]  Richard L. Berger,et al.  Optimization of the NIF ignition point design hohlraum , 2007 .

[14]  D. A. Dunnett.  Classical Electrodynamics , 2020, Nature.

[15]  Richard A. London,et al.  Unified model of secondary electron cascades in diamond , 2004 .

[16]  C. W. Struck,et al.  Scattering by ionization and phonon emission in semiconductors , 1980 .