TY - JOUR
T1 - Simulations of radiatively cooled magnetic reconnection driven by pulsed power
AU - Datta, Rishabh
AU - Crilly, Aidan
AU - Chittenden, Jeremy P.
AU - Chowdhry, Simran
AU - Chandler, Katherine
AU - Chaturvedi, Nikita
AU - Myers, Clayton E.
AU - Fox, William R.
AU - Hansen, Stephanie B.
AU - Jennings, Chris A.
AU - Ji, Hantao
AU - Kuranz, Carolyn C.
AU - Lebedev, Sergey V.
AU - Uzdensky, Dmitri A.
AU - Hare, Jack D.
N1 - Publisher Copyright:
Copyright © The Author(s), 2024. Published by Cambridge University Press.
PY - 2024/4/19
Y1 - 2024/4/19
N2 - Magnetic reconnection is an important process in astrophysical environments, as it reconfigures magnetic field topology and converts magnetic energy into thermal and kinetic energy. In extreme astrophysical systems, such as black hole coronae and pulsar magnetospheres, radiative cooling modifies the energy partition by radiating away internal energy, which can lead to the radiative collapse of the reconnection layer. In this paper, we perform two- and three-dimensional simulations to model the MARZ (Magnetic Reconnection on Z) experiments, which are designed to access cooling rates in the laboratory necessary to investigate reconnection in a previously unexplored radiatively cooled regime. These simulations are performed in GORGON, an Eulerian two-temperature resistive magnetohydrodynamic code, which models the experimental geometry comprising two exploding wire arrays driven by 20 MA of current on the Z machine (Sandia National Laboratories). Radiative losses are implemented using non-local thermodynamic equilibrium tables computed using the atomic code Spk, and we probe the effects of radiation transport by implementing both a local radiation loss model and multi-group radiation transport. The load produces highly collisional, super-Alfvénic (Alfvén Mach number), supersonic (Sonic Mach number) strongly driven plasma flows which generate an elongated reconnection layer (Aspect Ratio, Lundquist number). The reconnection layer undergoes radiative collapse when the radiative losses exceed the rates of ohmic and compressional heating (cooling rate/hydrodynamic transit rate =); this generates a cold strongly compressed current sheet, leading to an accelerated reconnection rate, consistent with theoretical predictions. Finally, the current sheet is also unstable to the plasmoid instability, but the magnetic islands are extinguished by strong radiative cooling before ejection from the layer.
AB - Magnetic reconnection is an important process in astrophysical environments, as it reconfigures magnetic field topology and converts magnetic energy into thermal and kinetic energy. In extreme astrophysical systems, such as black hole coronae and pulsar magnetospheres, radiative cooling modifies the energy partition by radiating away internal energy, which can lead to the radiative collapse of the reconnection layer. In this paper, we perform two- and three-dimensional simulations to model the MARZ (Magnetic Reconnection on Z) experiments, which are designed to access cooling rates in the laboratory necessary to investigate reconnection in a previously unexplored radiatively cooled regime. These simulations are performed in GORGON, an Eulerian two-temperature resistive magnetohydrodynamic code, which models the experimental geometry comprising two exploding wire arrays driven by 20 MA of current on the Z machine (Sandia National Laboratories). Radiative losses are implemented using non-local thermodynamic equilibrium tables computed using the atomic code Spk, and we probe the effects of radiation transport by implementing both a local radiation loss model and multi-group radiation transport. The load produces highly collisional, super-Alfvénic (Alfvén Mach number), supersonic (Sonic Mach number) strongly driven plasma flows which generate an elongated reconnection layer (Aspect Ratio, Lundquist number). The reconnection layer undergoes radiative collapse when the radiative losses exceed the rates of ohmic and compressional heating (cooling rate/hydrodynamic transit rate =); this generates a cold strongly compressed current sheet, leading to an accelerated reconnection rate, consistent with theoretical predictions. Finally, the current sheet is also unstable to the plasmoid instability, but the magnetic islands are extinguished by strong radiative cooling before ejection from the layer.
KW - astrophysical plasmas
KW - plasma instabilities
KW - plasma simulation
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U2 - 10.1017/S0022377824000448
DO - 10.1017/S0022377824000448
M3 - Article
AN - SCOPUS:85191387924
SN - 0022-3778
VL - 90
JO - Journal of Plasma Physics
JF - Journal of Plasma Physics
IS - 2
M1 - 905900215
ER -