Share Email Print
cover

Proceedings Paper

Pinhole closure measurements
Author(s): David Milam; James E. Murray; Kent G. Estabrook; Charles D. Boley; Walter D. Sell; Norman D. Nielsen; R. K. Kirkwood; Yuri A. Zakharenkov; Bedros B. Afeyan
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Spatial-filter pinholes and knife-edge samples were irradiated in vacuum by 1053-nm, 5-20 ns pulses at intensities to 500 GW/cm2. The knife-edge samples were fabricated of plastic, carbon, aluminum, stainless steel, molybdenum, tantalum, gold, and an absorbing glass. Time- resolved two-beam interferometry with a 40-ns probe pulse was used to observe phase shifts in the expanding laser- induced plasma. For al of these materials, at any time during square-pulse irradiation, the phase shift fell exponentially with distance from the edge of the sample.. The expansion was characterized by the propagation velocity V2(pi ) of the contour for a 2(pi) phase shift. To within experimental error, V2(pi ) was constant during irradiation at a particular intensity, and it increased linearly with intensity for intensities < 300 GW/cm2. For metal samples V2(pi ) exhibited an approximate M-0.5 dependence where M is the atomic mass. Plasmas of plastic, carbon, and absorbing glass produced larger phase shifts, and expanded more rapidly, than plasmas of heavy metals. The probe beam and interferometer were also used to observe the closing of pinholes. With planar pinholes, accumulation of on-axis plasma was observed along with the advance of plasma away from the edge of the hole. On-axis closure was not observed in square, 4-leaf pinholes.

Paper Details

Date Published: 23 July 1999
PDF: 6 pages
Proc. SPIE 3492, Third International Conference on Solid State Lasers for Application to Inertial Confinement Fusion, (23 July 1999); doi: 10.1117/12.354164
Show Author Affiliations
David Milam, Lawrence Livermore National Lab. (United States)
James E. Murray, Lawrence Livermore National Lab. (United States)
Kent G. Estabrook, Lawrence Livermore National Lab. (United States)
Charles D. Boley, Lawrence Livermore National Lab. (United States)
Walter D. Sell, Lawrence Livermore National Lab. (United States)
Norman D. Nielsen, Lawrence Livermore National Lab. (United States)
R. K. Kirkwood, Lawrence Livermore National Lab. (United States)
Yuri A. Zakharenkov, Lawrence Livermore National Lab. (United States)
Bedros B. Afeyan, Polymath Associates (United States)


Published in SPIE Proceedings Vol. 3492:
Third International Conference on Solid State Lasers for Application to Inertial Confinement Fusion
W. Howard Lowdermilk, Editor(s)

© SPIE. Terms of Use
Back to Top