Speaker
Description
Magnetic reconnection is a fundamental process that leads to rapid energy conversion in astrophysical, space and laboratory plasma systems. In modeling this process, most of the plasma fluid equations have employed an electrical resistivity to generate the magnetic dissipation required for magnetic reconnection to occur in a collisionless plasma. However, there has been no clear evidence that such a model is indeed appropriate in the reconnection diffusion region in terms of the kinetic physics. The present study demonstrates that, using a large-scale 3D kinetic simulation and analytical analysis, the spatial distribution of the non-ideal electric field is consistent with the dissipation due to the viscosity rather than the resistivity, when electromagnetic (EM) turbulence is dominant in the electron diffusion region (EDR). The effective viscosity is caused by the EM turbulence that is driven by the flow shear instabilities leading to the electron momentum transport across the EDR [1]. The result suggests a fundamental modification of the fluid equations using the resistivity in the Ohm’s law. In contrast, for the 2D current sheet without significant turbulence activity, the non-ideal field profile does not obey the simple form based on the viscosity. A general form of the of non-ideal electric field in 2D and 3D current sheets appropriate for fluid simulations is presented. The second part of the talk will be concerned with the time domain structures (TDS) associated with free energy sources (beams, thermal anisotropy, etc) that arise from the energy conversion process in magnetic reconnection and magnetic flux rope interaction. The results of both anomalous transport and TDS studies are connected to recent satellite observations (Magnetospheric Multiscale Satellites - MMS) [2] and laboratory magnetized plasma experiments.
[1] K. Fujimoto and R.D. Sydora, “The electron diffusion region dominated by electromagnetic turbulence in the reconnection current layer”, Phys. Plasmas, 30 (2), (2023), 022106 (10 pages).
[2] Z.H. Zhong, et al, “Electromagnetic viscosity supported anomalous electric field in the electron diffusion region of collisionless magnetic reconnection“, Nature Comm., 16, (2025), 10519 (11 pages).
| Keyword-1 | magnetic reconnection |
|---|---|
| Keyword-2 | plasma turbulence |
| Keyword-3 | kinetic simulation |