External Magnetic Fields and Their Impact on Electron Scale Instability

Recent research by D. Tsiklauri investigates the influence of external magnetic fields on electron scale Kelvin-Helmholtz instability (ESKHI) using particle-in-cell simulations. This study is particularly relevant in astrophysical contexts, such as when solar wind interacts with planetary magnetospheres or in active galactic nuclei (AGN) jets.

The findings indicate that the presence of an external magnetic field reduces the growth rate of the instability, similar to the effects observed in magnetohydrodynamic (MHD) scenarios. However, while MHD has established thresholds for stabilization, the specific thresholds for ESKHI require further analytical exploration. The research establishes an empirical relationship between the ESKHI growth rate and the strength of the external magnetic field, represented by the equation: ( \Gamma(B_0)\omega_{pe} = \frac{\Gamma_0\omega_{pe}}{A + B\bar{B_0}} ), where ( \Gamma_0 ) is the growth rate without an external field and ( \bar{B_0} ) is the ratio of the external field to the MHD stability threshold.

The implications of this research suggest that in environments with strong pre-existing magnetic fields, the generation of additional magnetic fields through ESKHI may be suppressed. This could serve as a natural mechanism to prevent excessive magnetic field generation in astrophysical settings. The study emphasizes the need for further analytical work to validate the empirical findings and enhance understanding of ESKHI dynamics under varying magnetic conditions.

For more details, the full paper can be accessed here. The study is titled "The effect of external magnetic field on electron scale Kelvin-Helmholtz instability" and was published on arXiv.