The charge state distributions of Fe, Na, and F are determined in a photoionized laboratory plasma using high resolution x-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter xi=20-25 erg cm s(-1) under near steady-state conditions. Line opacities are well fitted by a curve-of-growth analysis which includes the effects of velocity gradients in a one-dimensional expanding plasma. First comparisons of the measured charge state distributions with x-ray photoionization models show reasonable agreement.
The charge-state distribution in a well-characterized highly ionized Au plasma was accurately determined using time-resolved x-ray spectroscopy. Simultaneous measurements of the electron temperature and density allow the first direct comparisons with nonlocal thermodynamic equilibrium model predictions for the charge-state distribution of a highly ionized high- Z plasma in a nonradiative environment. The importance of two-electron atomic processes is clearly demonstrated.
We report the development of techniques to diagnose plasmas produced by X-ray photoionization of thin foils placed near the Z-pinch on the Sandia Z Machine. The development of 100+ TW X-ray sources enables access to novel plasma regimes, such as the photoionization equilibrium. To diagnose * This work was performed under the auspices of the
The lifefimes of the (2p)2
P
3/2 level in Si XII and the (2p
2)3
P
2,1,0, (2s2p)1
P
1 and the (2p
2)1
D
2 levels in Si XI have been determined using the beam-foil method. It is proposed that existing discrepancies between experimental and theoretical f values for the (2s
2)1
S
0-(2s2p)1
P
1 transition in some ions of the Be sequence may be the result of the inability of the experimentalist to account for strong cascading from the (2p
2)1
S
0 level.
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