Laser-plasma interactions relevant to Inertial Confinement Fusion

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Research into laser-driven inertial confinement fusion is now entering a critical juncture with the construction of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Many of the remaining unanswered questions concerning NIF involve interactions between lasers and plasmas. With the eventual goal of fusion power in mind, laser-plasma interactions relevant to laser fusion schemes is an important topic in need of further research. This work experimentally addresses some potential shortcuts and pitfalls on the road to laser-driven fusion power. Current plans on NIF have 192 laser beams directed into a small cylindrical cavity which will contain the ... continued below

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1000 Kilobytes pages

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Wharton, K.B. November 2, 1998.

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Research into laser-driven inertial confinement fusion is now entering a critical juncture with the construction of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). Many of the remaining unanswered questions concerning NIF involve interactions between lasers and plasmas. With the eventual goal of fusion power in mind, laser-plasma interactions relevant to laser fusion schemes is an important topic in need of further research. This work experimentally addresses some potential shortcuts and pitfalls on the road to laser-driven fusion power. Current plans on NIF have 192 laser beams directed into a small cylindrical cavity which will contain the fusion fuel; to accomplish this the beams must cross in the entrance holes, and this intersection will be in the presence of outward-flowing plasma. To investigate the physics involved, interactions of crossing laser beams in flowing plasmas are investigated with experiments on the Nova laser facility at LLNL. It was found that in a flowing plasma, energy is transferred between two crossing laser beams, and this may have deleterious consequences for energy balance and ignition in NIF. Possible solutions to this problem are presented. A recently-proposed alternative to standard laser-driven fusion, the ''fast ignitor'' concept, is also experimentally addressed in this dissertation. Many of the laser-plasma interactions necessary for the success of the fast ignitor have not previously been explored at the relevant laser intensities. Specifically, the transfer of high-intensity laser energy to electrons at solid-target interfaces is addressed. 20-30% conversion efficiencies into forward-propagated electrons were measured, along with an average electron energy that varied with the type of target material. The directionality of the electrons was also measured, revealing an apparent beaming of the highest energy electrons. This work was extended to various intensities and pulse lengths and a relationship between conversion efficiency and laser intensity was deduced. This work serves to advance knowledge of laser-plasma interactions relevant to a variety of laser-driven fusion schemes, and indicates directions for future research. These results should facilitate the success of NIF and other laser-fusion facilities.

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1000 Kilobytes pages

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  • Other Information: TH: Thesis (Ph.D.); Submitted to the Univ. of California, Los Angeles, CA (US)

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  • Report No.: UCRL-LR-132566
  • Report No.: DP0210000
  • Grant Number: W-7405-ENG-48
  • Office of Scientific & Technical Information Report Number: 12528
  • Archival Resource Key: ark:/67531/metadc625624

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • November 2, 1998

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  • June 16, 2015, 7:43 a.m.

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  • May 6, 2016, 2:40 p.m.

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Wharton, K.B. Laser-plasma interactions relevant to Inertial Confinement Fusion, thesis or dissertation, November 2, 1998; California. (digital.library.unt.edu/ark:/67531/metadc625624/: accessed December 17, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.