Electric field measurements from satellites-to-forbidden line ratios in an Omega-Upgrade laser-produced plasma. Semi-annual report, February 1--May 31, 1996
Under this FY-96 NLUF program, the authors began their search for satellite lines to forbidden transitions for localized laser-induced electric field measurements by preparing in their laboratory a flat-field grazing incidence spectrograph for use on the OMEGA-Upgrade facility. This involved wavelength calibration using a (small) laser-produced plasma, as well as designing and constructing a mounting table compatible with the large 60-beam target chamber at LLE. Beginning in April 1996 they installed and aligned the spectrograph at LLE. Following final alignment on Monday, April 29, they obtained the following day their first time-integrated spectral data in the 30--250 {angstrom} range. A total of 28 successful shots were obtained. For most shots, two beams of the OMEGA-Upgrade laser were used at nominal uv-pulse widths of 1.1 ns and energies ranging from 76--470 J/beam, with focal spots of 80--450 {micro}m and irradiances covering approximately 10{sup 14}--10{sup 16} Watt/cm{sup 2}. Planar targets used consisted of Mg and NaF, as well as boron mounted on a plastic film, with some of the former two overcoated with 5 {micro}m of CH on each side for containing the plasma, at least during the early portion of the pulse. Preliminary analyses indicate that they do indeed observe the desired Li-like L-shell spectra for oxygen, fluorine, sodium and magnesium, as well as L-shell lines in the corresponding H-(Balmer) and He-like species. Similarly, they recorded K-shell lines from B and C. Sample traces for Mg and Na fluoride from their soft x-ray spectrograph are shown. Both of these shots were obtained at a rather low applied irradiance of 2 X 10{sup 14} W/cm{sup 2}, and were chosen mainly for line identification. The parent Li-like 2s-3p allowed lines corresponding to the forbidden-line satellites sought for E-field determinations are clearly present. The calculated satellite line intensity relative to the intensity from this 2s-3p transition is {approximately} 3%.
- Research Organization:
- Maryland Univ., College Park, MD (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG03-96SF21014
- OSTI ID:
- 270791
- Report Number(s):
- DOE/ER--21014-1; ON: DE96012684
- Country of Publication:
- United States
- Language:
- English
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