Effects of Upper Hybrid Waves in the Electron Diffusion Region
Abstract
Magnetic reconnection is a fundamental physical process in plasma. The NASA's Magnetospheric Multiscale (MMS) mission has revealed that agyrotropic electrons and intense waves are prevalently present in the electron diffusion region of magnetic reconnection. Recent studies show that the crescent-shape agyrotropic electrons generate upper-hybrid waves electron Bernstein wave, which can affect the environment of the EDR via wave-particle interactions. Making use of two-dimensional particle-in-cell simulation, we investigate the effects of upper-hybrid waves. Our simulation code includes modeling of transient electrons near the EDR, and we use plasma parameters derived from the MMS observation on July 3rd, 2017. The energy history plot from the simulation shows that the total kinetic energy of electrons increases 5% of initial energy, and the maximum increase-rate of kinetic energy agrees with the MMS observation data ($\sim$ 0.4 mW/m$^{3}$) calculated by J$\cdot$E'. The parameter √{Hz}, an indicator of the gyrotropy of a pressure tensor, decreases as previous studies presented. However, the off-diagonal tensor term P$_{MN}$ increase (in LMN coordinates) due to the contribution from the core electrons. Comparing several simulation results using different values of beam densities, we found that changes of such parameters seem to be proportional to the linear growth rate of upper-hybrid waves. It is known that the gradient of P$_{MN}$ plays a significant role in sustaining the reconnection electric field. Therefore, upper-hybrid waves might affect the EDR environment via not only wave-particle interaction but also contribution to the pressure tensor terms. We also present more simulation results using different beam densities, which can determine the intensities of wave and wave-particle interactions.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1098D