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Evidence For Population Inversion And Possible Lasing At 150.6, 154.6 And 187.3A In Pulsed Power Driven Z-Pinches*
Author(s): M Krishnan; T Nash; P D LePell
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Paper Abstract

The DNA/PITHON pulsed power generator was used to produce hot, dense, aluminum plasmas in a Z-pinch configuration. An annulus of neon gas was radially imploded on to a parylene capillary on axis, which wa$ coatqd with aluminum. The pinch produced 3 cm and 5 cm long Al plasmas with densities - 1020 cm' and temperatures - 500 eV, with a 25 ns duration. After the implosion, the Al plasma expanded and cooled for the next 50 ns, producing Li-like Al XI ions by recombination from He-like Al XII ions. A time-gated, grazing incidence spectrograph (MCPIGS) was used to image the expanding plasma and to capture three consecutive 25 ns duration spectra. The Al XI, 4f-3d and 4d-3p lines at 154.6 and 150.6Å were observed to be.anomalously bright compared to the Al XI, 4d-2p line. Also, the Ne X, 4-3 line at 187.3A was brighter than the Ne X, 4-2 Balmer-p line. Spatial and temporal variations of these lines suggest an inversion of the 4d and 4f levels in Al XI and of the n = 4 level in Ne X, driven by three-body recombination. A rough estimate of the gain-length product for these lines is between 3 and 4. From measured K-line yields in neon, using branching ratios and detector response, it was estimated that the total energy output of these laser lines ::: 60 mJ/pulse. Further confirmation of lasing awaits experiments in which on-axis and off-axis XUV measurements, as well as systematic length scaling, are planned. However, these early results signify a major milestone for pulsed power driven X-ray lasers. The power in these lasers is ~ 2 MW. These power levels are comparable to those,produced in the glass laser driven X-ray lasers at Lawrence Livermore National Labs (LLNL).1" If these recombination laser. The 4f-3d transition has an oscillator strength of unity, and recombination followed by cascades will feed the 4f level very effectively. Collisional mixing of the n = 4 levels will also pump the 4d level.

Paper Details

Date Published: 27 April 1988
PDF: 5 pages
Proc. SPIE 0875, Short and Ultrashort Wavelength Lasers, (27 April 1988); doi: 10.1117/12.943878
Show Author Affiliations
M Krishnan, Physics International Comnany (United States)
T Nash, Physics International Company (United States)
P D LePell, Physics International Company (United States)

Published in SPIE Proceedings Vol. 0875:
Short and Ultrashort Wavelength Lasers
Randy C.R. Jones, Editor(s)

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