Stix Award: Magnetic Reconnection Driven by Pulsed-Power
ORAL · Invited
Abstract
In this talk, I will describe a series of experiments carried out over the last decade to study magnetic reconnection. Reconnection is a ubiquitous process throughout the Universe, in which sheared magnetic field lines come together within a plasma, generating an intense sheet of electrical current which breaks the frozen-in condition of ideal magneto-hydrodynamics. Within this current sheet (or reconnection layer), magnetic field lines change their topology and reconnection, and magnetic energy is dissipated in the form of heat, fast outflows, and energetic particles.
Reconnection has been extensively studied in theory, simulations, astronomical observations, by in-situ spacecraft and in the laboratory. Pulsed-power-driven experiments heat initially solid wires to produce hot [10 eV], dense [10^18 cm^-3], fast-moving [50 km/s] plasma flows with embedded magnetic fields [3 T] on centimeter scales, in a beta ~ 1 regime which complements other experiments.
The first of these experiments studied anti-parallel reconnection with different plasma compositions. Aluminium plasmas led to rapid radiative cooling at relatively low Lundquist numbers, whereas carbon plasmas produced plasmoids within the reconnection layer, associated with anomalously fast heating. More recently, we have explored guide-field reconnection, and observed quadrupolar density structures associated with two-fluid effects.
I will also discuss experiments scaled to use the Z Machine at Sandia National laboratories, the world's largest pulsed-power generator. In these experiments, we were able to produce plasmoids in a reconnection layer undergoing strong radiative cooling. We observed that the X-ray emission was localised to the plasmoids, which were rapidly extinguished as they radiatively cooled.
Reconnection has been extensively studied in theory, simulations, astronomical observations, by in-situ spacecraft and in the laboratory. Pulsed-power-driven experiments heat initially solid wires to produce hot [10 eV], dense [10^18 cm^-3], fast-moving [50 km/s] plasma flows with embedded magnetic fields [3 T] on centimeter scales, in a beta ~ 1 regime which complements other experiments.
The first of these experiments studied anti-parallel reconnection with different plasma compositions. Aluminium plasmas led to rapid radiative cooling at relatively low Lundquist numbers, whereas carbon plasmas produced plasmoids within the reconnection layer, associated with anomalously fast heating. More recently, we have explored guide-field reconnection, and observed quadrupolar density structures associated with two-fluid effects.
I will also discuss experiments scaled to use the Z Machine at Sandia National laboratories, the world's largest pulsed-power generator. In these experiments, we were able to produce plasmoids in a reconnection layer undergoing strong radiative cooling. We observed that the X-ray emission was localised to the plasmoids, which were rapidly extinguished as they radiatively cooled.
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Publication: 1. Hare, J. D. et al. Anomalous Heating and Plasmoid Formation in a Driven Magnetic Reconnection Experiment. Physical Review Letters 118, 085001 (2017).<br>2. Datta, R. et al. Plasmoid Formation and Strong Radiative Cooling in a Driven Magnetic Reconnection Experiment. Phys. Rev. Lett. 132, 155102 (2024).<br>3. Varnish, T. W. O. et al. Quadrupolar density structures in driven magnetic reconnection experiments with a guide field. Physics of Plasmas 32, 022118 (2025).
Presenters
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Jack D Hare
Cornell University
Authors
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Jack D Hare
Cornell University