Estimation of electron temperature using gated X-ray pinhole images of magnetic reconnection experiments at the NIF

ORAL

Abstract

We present results from high-aspect ratio magnetic reconnection experiments driven at the National Ignition Facility. In these experiments, 40 beams are tiled to produce two elongated laser-driven plumes which are self-magnetized by the Biermann battery effect [1]. As these plumes expand, they collide and drive magnetic reconnection. A gated X-ray framing camera with micro-channel plate (MCP) detector produces 16 filtered images of the formation and evolution of both the plumes and current sheet up to 8 ns after the lasers fire. The 2-dimensional electron temperature is estimated by taking the ratio of intensity of these images obtained with different filters, a technique developed for the sub-keV temperatures expected in these experiments [2]. The data show that the plasma plumes are initially several hundreds of eV hot and collide at ~ 2 ns after initial laser irradiation. As the current sheet forms, we observe that it becomes hotter than the plumes, and its temperature remains constant throughout the rest of the experimental time-frame. We discuss the interplay of shock heating, radiative cooling, and magnetic reconnection in the energy balance of the current sheet.



[1] Fox, et al. arXiv:2003.06351 (2020)

[2] Schaeffer, et al. RSI (2020)

*We thank the NIF Discovery Science Program for facilitating these experiments. Support for these experiments was provided by the U.S. DOE, Office of Fusion Energy Sciences, under FWP SW1626 FES. This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and under DOE Award Nos. DE- SC-0016249 and DE-NA-0003856, and Field Work Proposal No. 4507 under DOE Contract No. DE-AC02-09CH11466.

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Presenters

  • Vicente Valenzuela-Villaseca

    • Princeton University

Authors

  • Vicente Valenzuela-Villaseca

    • Princeton University

  • Jacob M Molina

    • Princeton University

  • Sophia Malko

    • Princeton Plasma Physics Laboratory

  • Jesse Griff-McMahon

    • Princeton University

  • Michael J Rosenberg

    • Laboratory for Laser Energetics, University of Rochester
    • University of Rochester

  • Hye-Sook Park

    • LLNL

  • Gennady Fiksel

    • University of Michigan

  • Daniel H Kalantar

    • Lawrence Livermore Natl Lab

  • Derek B Schaeffer

    • University of California, Los Angeles
    • University of California Los Angeles

  • William R Fox

    • Princeton Plasma Physics Laboratory