Relativistic-electron-driven magnetic reconnection in the laboratory

Journal Article · 23 October 2018 · Physical Review E

DOI: https://doi.org/10.1103/PhysRevE.98.043207 · OSTI ID:1478756

Raymond, A. E. ^[1]; Dong, C. F. ^[2]; McKelvey, A. ^[3]; Zulick, C. ^[4]; Alexander, N. ^[5]; Bhattacharjee, A. ^[2]; Campbell, P. T. ^[4]; Chen, H. ^[6]; Chvykov, V. ^[4]; Del Rio, E. ^[5]; Fitzsimmons, P. ^[5]; Fox, W. ^[2]; Hou, B. ^[4]; Maksimchuk, A. ^[4]; Mileham, C. ^[7]; Nees, J. ^[4]; Nilson, P. M. ^[7]; Stoeckl, C. ^[7]; Thomas, A. G. R. ^[4]; Wei, M. S. ^[5] ; Yanovsky, V. ^[4]; Krushelnick, K. ^[4]; Willingale, L. ^[4]

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1. Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science; University of Michigan
2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
3. Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science; Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
4. Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science
5. General Atomics, San Diego, CA (United States)
6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
7. Univ. of Rochester, NY (United States). Lab. for Laser Energetics

Magnetic reconnection is a fundamental process occurring in many plasma systems. Magnetic field lines break and reconfigure in to a lower energy state, converting released magnetic field energy into plasma kinetic energy. Around some of the universe’s most energetic objects, such as gamma ray burst or active galactic nuclei, where the magnetic field energy exceeds the plasma rest mass energy, the most extreme magnetic reconnection in the relativistic regime is theorized. The pre- sented experiments and three-dimensional particle-in-cell modeling recreate in the laboratory the scaled plasma conditions necessary to access the relativistic electron regime and therefore approach conditions around these distant, inaccessible objects. High-power, ultrashort laser pulses focused to high-intensity (I > 2.5 × 1018 Wcm-2) on solid targets produces relativistic temperature electrons within the focal volume. The hot electrons are largely confined to the target surface and form a ra- dial surface current that generates a huge, expanding azimuthal magnetic field. Focusing two laser pulses in close proximity on the target surface leads to oppositely directed magnetic fields being driven together. The fast electron motion due to the magnetic reconnection is inferred using an ex- perimental x-ray imaging technique. The x-ray images enable the measurement of the reconnection layer dimensions and temporal duration. The reconnection rates implied from the aspect ratio of the reconnection layer, δ/L ≈ 0.3, was found to be consistent over a range of experimental pulse durations (40 fs–20 ps) and agreed with the modeling. Further experimental evidence for magnetic reconnection is the formation of a nonthermal electron population shown by the modeling to be accelerated in the reconnection layer.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Univ. of Michigan, Ann Arbor, MI (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344; NA0002727
• OSTI ID: 1478756
• Report Number(s): LLNL-JRNL-760956
• Journal Information: Physical Review E, Journal Name: Physical Review E Journal Issue: 4 Vol. 98; ISSN PLEEE8; ISSN 2470-0045
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English