This research investigates the electrical resistivity of a plasma during the collision of magnetic flux ropes, which are common structures in astrophysical plasmas. The researchers performed laboratory experiments using the Large Plasma Device (LaPD) at UCLA, measuring the magnetic field, plasma potential, plasma flow, temperature, and density at various spatial locations. They found that the traditional Ohm's Law (describing resistivity) could not be used to calculate the resistivity due to non-local effects. Instead, they used the Kubo conductivity formula, which is derived from the fluctuation-dissipation theorem, to determine the global resistivity. The results indicate that the resistivity is enhanced in regions where the magnetic field lines reconnect and the current density is large, suggesting that the process is related to the scattering of electrons by waves or turbulence in the plasma.

Basic Plasma Science Facility: https://plasma.physics.ucla.edu

Article being discussed: W. Gekelman, T. DeHaas, P. Pribyl, S. Vincena, B. Van Compernolle, R. Sydora, and S. K. P. Tripathi, "Nonlocal Ohm's Law, Plasma Resistivity, and Reconnection During Collisions of Magnetic Flux Ropes," ApJ 853 33, (2018); https://doi.org/10.3847/1538-4357/aa9fec

The Basic Plasma Science Facility is a Collaborative Research Facility that is primarily funded by the US Department of Energy Fusion Energy Sciences program, with additional funding from the National Science Foundation.