Energy transport in plasmas produced by a high brightness krypton fluoride laser focused to a line

Journal Article · Sun May 01 00:00:00 EDT 1994 · Physics of Plasmas; (United States)

DOI:https://doi.org/10.1063/1.870726· OSTI ID:6686841

Al-Hadithi, Y; Tallents, G J ^[1]; Zhang, J ^[2]; Key, M H; Norreys, P A; Kodama, R ^[3]

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1. Department of Physics, University of Essex, Colchester CO4 3SQ (United Kingdom)
2. Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom)
3. Central Laser Facility, Rutherford Appleton Laboratory, Chilton OX11 0QX (United Kingdom)

A high brightness krypton fluoride Raman laser (wavelength 0.268 [mu]m) generating 0.3 TW, 12 ps pulses with 20 [mu]rad beam divergence and a prepulse of less than 10[sup [minus]10] has been focused to produce a 10 [mu]m wide line focus (irradiances [similar to]0.8--4[times]10[sup 15] W cm[sup [minus]2]) on plastic targets with a diagnostic sodium fluoride (NaF) layer buried within the target. Axial and lateral transport of energy has been measured by analysis of x-ray images of the line focus and from x-ray spectra emitted by the layer of NaF with varying overlay thicknesses. It is shown that the ratio of the distance between the critical density surface and the ablation surface to the laser focal width controls lateral transport in a similar manner as for previous spot focus experiments. The measured axial energy transport is compared to MEDUSA [J. P. Christiansen, D. E. T. F. Ashby, and K. V. Roberts, Comput. Phys. Commun. [bold 7], 271 (1974)] one-dimensional hydrodynamic code simulations with an average atom post-processor for predicting spectral line intensities. An energy absorption of [similar to]10% in the code gives agreement with the experimental axial penetration. Various measured line ratios of hydrogen- and helium-like Na and F are investigated as temperature diagnostics in the NaF layer using the RATION [R. W. Lee, B. L. Whitten, and R. E. Strout, J. Quant. Spectrosc. Radiat. Transfer [bold 32], 91 (1984)] code.

• OSTI ID: 6686841
• Journal Information: Physics of Plasmas; (United States), Vol. 1:5; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
LASER-PRODUCED PLASMA
ENERGY TRANSFER
ABLATION
COMPUTER CODES
EMISSION SPECTRA
KRYPTON FLUORIDE LASERS
SODIUM FLUORIDES
X-RAY SPECTRA
ALKALI METAL COMPOUNDS
EXCIMER LASERS
FLUORIDES
FLUORINE COMPOUNDS
GAS LASERS
HALIDES
HALOGEN COMPOUNDS
LASERS
PLASMA
SODIUM COMPOUNDS
SPECTRA
700330* - Plasma Kinetics
Transport
& Impurities- (1992-)
700350 - Plasma Production
Heating
Current Drive
& Interactions- (1992-)