What is it about?

Magnetic reconnection can be observed occurring in space as well as in laboratory experiments. Recently, the Terrestrial Reconnection EXperiment (TREX) at the University of Wisconsin-Madison has started using supercomputers at Los Alamos National Laboratory (LANL) to simulate the experiment and compare the experimental and simulated results. In this paper, we demonstrate that the speed at which the reconnection process occurs is consistent between these two sets of data and that the way the speed of reconnection changes as different properties of the experiment or simulation change is comparable in both cases.

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Why is it important?

Magnetic reconnection is a process that changes the shape of interacting magnetic fields and transfers energy from the fields into the particles that travel through the fields. Reconnection occurs naturally on the surface of the Sun (causing the solar wind) and where the solar wind meets the Earth's magnetic field. This second scenario allows solar wind particles to enter Earth's atmosphere. Normally, these particles aren't dense enough or energetic enough to do anything more than cause the polar auroras (such as the Aurora Borealis that can usually be seen in the night skies of Alaska, Canada, and northern Europe). However, when a particularly large group of energetic particles enters Earth's atmosphere, they can induce power surges that damage satellites, power grids, and global communications. One such event in 1989 caused the entire Canadian province of Quebec to lose power for nine hours and the communications blackout triggered fears of an imminent nuclear attack. Understanding the reconnection process as it occurs at the Sun and at the Earth is crucial to predicting when these geomagnetic storms will occur; with enough warning, crucial systems can be powered down to prevent them from being harmed. While reconnection in the Earth's magnetic field can be measured by satellites, experiments and simulations here on Earth can also provide insight without the constraints of a space-based missions. This paper studies the rate at which the reconnection process occurs in both experiments and simulations, showing agreement between both and motivating further comparisons between these two areas of investigation and the probe measurements taken in space.


This paper, in conjunction with another published in the Journal of Geophysical Research Space Physics in the summer of 2021, represents the first round of peer-reviewed results from the collaboration between UW-Madison and LANL. I have been very fortunate to be at the center of this collaboration under the guidance of my advisor at UW-Madison and my host at LANL; I hadn't expected my graduate career to transition from a solely-experimental focus to an experimental-simulation hybrid but I'm extremely glad that it did. I think that using experiments to model simulations and simulations to inform experimental goals is a productive avenue of motivating new research pathways and encouraging collaborative problem-solving between research groups that otherwise tend not to communicate very much outside of conferences.

Samuel Greess
University of Wisconsin Madison

Read the Original

This page is a summary of: Kinetic simulations verifying reconnection rates measured in the laboratory, spanning the ion-coupled to near electron-only regimes, Physics of Plasmas, October 2022, American Institute of Physics,
DOI: 10.1063/5.0101006.
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