The study of parametric instabilities in NIF-scale plasmas on Nova [electronic resource]
At the same time we experimentally reproduced the plasma conditions expected within the NIF using plasmas produced by the Nova laser. The plasmas were created by irradiating a thin walled gas balloon or a sealed hohlraum containing of order one atmosphere of a low-Z gas (e.g. C₅H₁₂, C₅D₁₂ or CO₂). W...
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Online Access |
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
1994.
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| Subjects: |
| Summary: | At the same time we experimentally reproduced the plasma conditions expected within the NIF using plasmas produced by the Nova laser. The plasmas were created by irradiating a thin walled gas balloon or a sealed hohlraum containing of order one atmosphere of a low-Z gas (e.g. C₅H₁₂, C₅D₁₂ or CO₂). When the gas is ionized and heated the resultant plasmas are homogeneous, and of high density (∼10²¹ electron/cm³) and temperature (∼3 keV) with large scale density scale lengths (∼2 mm). Nine of the Nova beams were used to produce the plasma, the tenth beam was configured as an interaction beam that was sent through the performed plasma after a delay of order 500 psec. The SRS and SBS scattered from the plasma, together with the effects of the plasma on the transmitted beam, were studied as a function of the interaction beam intensity, beam smoothing and plasma constituents. The interaction beam was smoothed by using radon phase plates (RPPs), and 4 different colors within the f/8 beam to mimic the NIF laser architecture. The 4-color set-up divided the f/8 beam in to 4 separate quadrants each of which had its wavelength shifted relative to the other quadrants. The wavelength separation of the colors was approximately 1.4Å at 3ω. Since each beam quadrant could have its frequency conversion crystals individually tuned for its wavelength, the 4-color scheme approximated ̀̀bandwidth̀̀ on the interaction beam without losing 3ω conversion efficiency. We have also studied the use of a laser bandwidth of approximately 0.7Å and smoothing by Spectral Dispersion (SSD) with all of the quadrants set at the same color, to further reduce the reflected SBS. These studies were performed with both f/4.3 and f/8 interaction beam focusing. |
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| Item Description: | Published through SciTech Connect. 09/26/1994. "ucrl-jc--118524" " conf-940933--45" "DE95014685" 15. international conference on plasma physics and controlled nuclear fusion research, Madrid (Spain), 26 Sep - 1 Oct 1994. Berger, R.L.; Back, C.A.; MacGowan, B.J. |
| Physical Description: | 6 p. : digital, PDF file. |