Mass Ratio Dependence of Strong Guide Field Reconnection Based on a Gyrokinetic Electron and Fully Kinetic Ion Particle Simulation

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Abstract
Magnetic reconnection under a strong guide field B G / B y 0 ≫ 1 , as in solar wind and laboratory plasmas, is investigated using the gyrokinetic electron and fully kinetic ion (GeFi) particle simulation model, where B y 0 is the antiparallel component of the magnetic field and B G is the guide field. Cases with two-dimensional force-free current sheets are presented in conditions with a large guide field and low plasma beta, similar to the reconnection events associated with solar flares. To gain insights into how the ion-to-electron mass ratio ( m i / m e ) and normalized guide field ( B G / B y 0 ) affect the rate and structures of reconnection, we present a series of simulations by varying m i / m e from 100 to 1836 and B G / B y 0 from 5 to 15. First, linear eigenmode analysis is performed for the collisionless tearing mode. We find that the eigenmode structure and growth rate of the tearing mode obtained from the GeFi simulation are in excellent agreement with the eigenmode theory for strong B G . Subsequently, we employ GeFi simulations to explore the reconnection rate and current sheet structure across a wide range of m i / m e and B G / B y 0 . Intriguingly, it is found that the reconnection rate is insensitive to m i / m e . The growth rate of the tearing mode, however, has a strong dependence on m i / m e . The reconnection rate exhibits a clear increase with decreasing B G / B y 0 and also strongly depends on B G / B y 0 . Furthermore, the length of the electron diffusion region increases with m i / m e . These findings advance understanding of the reconnection dynamics in solar flares and other astrophysical phenomena.
Funding Information
  • National Science Foundation (OIA-1655280)
  • MOST ∣ National Natural Science Foundation of China (42104158)
  • MOST ∣ National Natural Science Foundation of China (41804160)

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