Electron-scale Kelvin-Helmholtz Instability In Magnetized Shear Flows

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Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are found in a number of astrophysical scenarios. Naturally ESKHI is topic to a background magnetic field, however an analytical dispersion relation and an accurate progress rate of ESKHI underneath this circumstance are long absent, as former MHD derivations are not relevant within the relativistic regime. We current a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with few assumptions. ESKHI linear growth charges in sure circumstances are numerically calculated. We conclude that the presence of an external magnetic field decreases the utmost instability progress fee usually, however can barely improve it when the shear velocity is sufficiently excessive. Also, the exterior magnetic area results in a larger cutoff wavenumber of the unstable band and increases the wavenumber of the most unstable mode. PIC simulations are carried out to confirm our conclusions, the place we also observe the suppressing of kinetic DC magnetic field technology, ensuing from electron gyration induced by the exterior magnetic discipline. Electron-scale Kelvin-Helmholtz instability (ESKHI) is a shear instability that takes place at the shear boundary the place a gradient in velocity is present.



Despite the importance of shear instabilities, ESKHI was only acknowledged lately (Gruzinov, 2008) and remains to be largely unknown in physics. KHI is stable under a such condition (Mandelker et al., durable garden trimmer 2016). These make ESKHI a promising candidate to generate magnetic fields in the relativistic jets. ESKHI was first proposed by Gruzinov (2008) within the limit of a chilly and collisionless plasma, Wood Ranger Power Shears website Wood Ranger Power Shears for sale Power Shears for sale where he additionally derived the analytical dispersion relation of ESKHI development charge for symmetrical shear flows. PIC simulations later confirmed the existence of ESKHI (Alves et al., 2012), discovering the generation of typical electron vortexes and durable garden trimmer magnetic discipline. It is noteworthy that PIC simulations also found the technology of a DC magnetic subject (whose common alongside the streaming course shouldn't be zero) in company with the AC magnetic field induced by ESKHI, whereas the previous is not predicted by Gruzinov. The generation of DC magnetic fields is due to electron thermal diffusion or durable garden trimmer mixing induced by ESKHI across the shear interface (Grismayer et al., 2013), which is a kinetic phenomenon inevitable in the settings of ESKHI.



A transverse instability labelled mushroom instability (MI) was additionally found in PIC simulations concerning the dynamics within the airplane transverse to the velocity shear (Liang et al., 2013a; Alves et al., 2015; Yao et al., 2020). Shear flows consisting of electrons and positrons are also investigated (Liang et al., 2013a, b, 2017). Alves et al. ESKHI and numerically derived the dispersion relation within the presence of density contrasts or clean velocity shears (Alves et al., 2014), that are each discovered to stabilize ESKHI. Miller & Rogers (2016) extended the speculation of ESKHI to finite-temperature regimes by contemplating the strain of electrons and derived a dispersion relation encompassing both ESKHI and MI. In pure eventualities, ESKHI is often topic to an exterior magnetic subject (Niu et al., 2025; Jiang et al., 2025). However, Wood Ranger Power Shears manual Wood Ranger Power Shears warranty Power Shears shop works talked about above have been all carried out within the absence of an external magnetic subject. While the theory of fluid KHI has been extended to magnetized flows a very long time in the past (Chandrasekhar, 1961; D’Angelo, 1965), the habits of ESKHI in magnetized shear flows has been fairly unclear.



Up to now, the only theoretical concerns concerning this drawback are presented by Che & Zank (2023) and Tsiklauri (2024). Both works are limited to incompressible plasmas and a few type of MHD assumptions, which are only valid for small shear velocities. Therefore, their conclusions cannot be immediately utilized in the relativistic regime, where ESKHI is predicted to play a major position (Alves et al., 2014). Simulations had reported clear discrepancies from their concept (Tsiklauri, 2024). As Tsiklauri highlighted, a derivation of the dispersion relation with out extreme assumptions is critical. This kinds part of the motivation behind our work. On this paper, we will consider ESKHI beneath an external magnetic subject by immediately extending the works of Gruzinov (2008) and Alves et al. 2014). This means that our work is carried out in the limit of chilly and collisionless plasma. We adopt the relativistic two-fluid equations and avoid any type of MHD assumptions. The paper is organized as follows. In Sec. 1, we current a short introduction to the background and topic of ESKHI.