Nonlocal Ohms Law, Plasma Resistivity, and Reconnection During Collisions of Magnetic Flux Ropes

Abstract

The plasma resistivity was evaluated in an experiment on the collision of two magnetic flux ropes. Whenever the ropes collide, some magnetic energy is lost as a result of reconnection. Volumetric data, in which all the relevant time-varying quantities were recorded in detail, are presented. Ohm's law is shown to be nonlocal and cannot be used to evaluate the plasma resistivity. The resistivity was instead calculated using the AC Kubo resistivity and shown to be anomalously high in certain regions of space.

Laboratory Measurement of Large‐Amplitude Whistler Pulses Generated by Fast Magnetic Reconnection

“…Typical signatures of reconnection include X-rays, localized heating, and magnetized waves. This process is considered to be responsible for large impulsive releases of energy in solar flares, magnetic storms in Earth's magnetotail, disruptions in fusion devices, and laboratory circumstances simulating these solar and space plasmas (Cassak et al, 2008;Gekelman et al, 2018;Marshall et al, 2018;Moser & Bellan, 2012;Priest & Forbes, 2000;Xiao et al, 2010;Yamada et al, 2016). In these systems, the collisionless reconnection rate is typically orders of magnitude faster than resistive reconnection (Brown et al, 2006;Øieroset et al, 2001;Yamada et al, 2006).…”

Spiky electric and magnetic field structures in flux rope experiments

“…The height of the markers is proportional to the number of TDS e s at that location. that the ropes resistivity is anomalous and cannot be described by a local Ohm's law (36,37). The TDS e s could play a role in this.…”

Using topology to locate the position where fully three-dimensional reconnection occurs

“…from which the plasma currents are derived. Other quantities measured were the plasma flow, electron temperature, density, and plasma potential, which were used to show that Ohms' law is nonlocal [62]. All quantities were measured at 42,200 spatial locations and 7000 timesteps (δt = 3.3X10 −7 s).…”

“…Most 3D work use the Magnetohydrodynamic (MHD) formalism, with the addition of terms for the plasma resistivity. The resistivity is a term in Ohms law, but it is not at all clear if that can be used at all [62]. To the author's knowledge none of the theories can be used to pinpoint the location of reconnection when null points or lines do not exist.…”

“…This work fits well in the topical collection on "Interfaces, Mixing and Non-equilibrium dynamics". The ropes interact with each other and mix with the cooler, less dense, background plasma as evidenced by diffusion of the plasma current electron temperature and rope density as a function of distance from their origin [62,63]. The interface between the ropes and background magnetic fields is blurred as the currents diffuse.…”