Essay About Population Inversion And Production Of Uniform Dense Titanium Plasmas

Production of Uniform Dense Titanium Plasmas for Experiments on Atlas
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Finhole camera imaging of an ablative capillary discharge
investigated for the development of a soft x-ray laser
R Dussart, S. Gatze, D. Hong, J. Pons, C. Cachoncinlle,
J.-M. Pouvesle, C. Fleurier
GREML, UMR6606 CNRSKJniversite dOrlCans, B.P. 6744,
45067 OrlCans Cedex 2, France
Abstract
End-on images of an ablative capillary discharge have
been obtained using a time resolved pinhole camera. This
experiment was motivated by the feasibility study of a soft
x-ray laser in a highly ionized carbon plasm created by
electrical discharges. Such laser effects have already been
observed in laser pumped x-ray laser experiments [l]. The
population inversion can be obtained by a collisional
recombination scheme, which is favored by a rapid cooling of
the fully stripped carbon plasma
In our experiment, the plasma was created by injecting
a high current pulse of several tens of kA in 100 m into a
1 mm diameter capillary initially under vacuum. It was
composed of highly ionized carbon and stripped hydrogen
provided by the polyethylene capillary wall. Soft x-ray
production could be spatially localized by analyzing images
obtained by means of a 0.1 pm polyimide filter, which was
installed between the discharge and the camera. The
,+olyimide filter had a good transmission for soft x-rays fkom
the 10-20 nm wavelength range. Spectroscopic investigations
had been previously performed to analyze the plasma
emission [2].
The time evolution of the plasma radial distribution
was determined for two capillary lengths (10 and 16 mm). For
a 23 kA injected current pulse, an emission ring mostly
composed of W emitters showed the ablated material
provided by the wall. For a 48 kA injected current pulse, the
profiles were analyzed in details showing the plasma heating
followed by its cooling due to thermal diffusion from the
capillary wall. No evident z-pinch occurred on the frst
current pulse. The results of time resolved spectra were
consistent with those observed with pinhole experiments.
Different