Non-thermal electron acceleration from magnetically driven reconnection in a laboratory plasma
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- Princeton University, NJ (United States)
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Princeton University, NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- University of Rochester, NY (United States)
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- University of Michigan, Ann Arbor, MI (United States)
- National Institute for Physics and Nuclear Engineering, Bucharest-Magurele (Romania); University of Bucharest (Romania); Sorbonne University, Paris (France)
- National Institute for Physics and Nuclear Engineering, Bucharest-Magurele (Romania)
- Sorbonne University, Paris (France)
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); University of Maryland, College Park, MD (United States)
- Osaka University (Japan)
Magnetic reconnection rapidly converts magnetic energy into some combination of plasma flow energy, thermal energy and non-thermal energetic particles. Various reconnection acceleration mechanisms have been theoretically proposed and numerically studied in different collisionless and low-β environments, where β refers to the plasma-to-magnetic pressure ratio. These mechanisms include Fermi acceleration, betatron acceleration, parallel electric field acceleration along magnetic fields and direct acceleration by the reconnection electric field. However, none of them have been experimentally confirmed, as the direct observation of non-thermal particle acceleration in laboratory experiments has been difficult due to short Debye lengths for in situ measurements and short mean free paths for ex situ measurements. Here we report the direct measurement of accelerated non-thermal electrons from magnetically driven reconnection at low β in experiments using a laser-powered capacitor coil platform. We use kilojoule lasers to drive parallel currents to reconnect megagauss-level magnetic fields in a quasi-axisymmetric geometry. The angular dependence of the measured electron energy spectrum and the resulting accelerated energies, supported by particle-in-cell simulations, indicate that the mechanism of direct electric field acceleration by the out-of-plane reconnection electric field is at work. Scaled energies using this mechanism show direct relevance to astrophysical observations.
- Research Organization:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Univ. of Rochester, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- SC0020103; GR523126; PHY-2020249; 89233218CNA000001; SC0020434
- OSTI ID:
- 1914093
- Alternate ID(s):
- OSTI ID: 2008263; OSTI ID: 2341497
- Report Number(s):
- LA-UR-21-25861; PHY-2020249; TRN: US2312217
- Journal Information:
- Nature Physics, Vol. 19, Issue 2; ISSN 1745-2473
- Publisher:
- Nature Publishing Group (NPG)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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