Electron-scale Kelvin-Helmholtz Instability In Magnetized Shear Flows
Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are present in a number of astrophysical scenarios. Naturally ESKHI is subject to a background magnetic discipline, however an analytical dispersion relation and an accurate development fee of ESKHI beneath this circumstance are lengthy absent, as former MHD derivations are not relevant in the relativistic regime. We current a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with few assumptions. ESKHI linear progress charges in sure instances are numerically calculated. We conclude that the presence of an exterior magnetic field decreases the utmost instability growth rate in most cases, but can slightly improve it when the shear velocity is sufficiently high. Also, the external magnetic field leads to a larger cutoff wavenumber of the unstable band and will increase the wavenumber of essentially the most unstable mode. PIC simulations are carried out to verify our conclusions, where we also observe the suppressing of kinetic DC magnetic subject era, ensuing from electron gyration induced by the exterior magnetic discipline. Electron-scale Kelvin-Helmholtz instability (ESKHI) is a shear instability that takes place on the shear boundary the place a gradient in velocity is present.
Despite the significance of shear instabilities, ESKHI was only recognized just lately (Gruzinov, 2008) and stays to be largely unknown in physics. KHI is stable under a such situation (Mandelker et al., 2016). These make ESKHI a promising candidate to generate magnetic fields within the relativistic jets. ESKHI was first proposed by Gruzinov (2008) in the limit of a cold and collisionless plasma, the place he also derived the analytical dispersion relation of ESKHI progress charge for symmetrical shear flows. PIC simulations later confirmed the existence of ESKHI (Alves et al., 2012), discovering the technology of typical electron vortexes and magnetic area. It's noteworthy that PIC simulations also found the technology of a DC magnetic discipline (whose average along the streaming course is just not zero) in company with the AC magnetic area induced by ESKHI, while the previous is not predicted by Gruzinov. The technology of DC magnetic fields is because of electron thermal diffusion or mixing induced by ESKHI across the shear interface (Grismayer et al., 2013), Wood Ranger Tools which is a kinetic phenomenon inevitable within the settings of ESKHI.
A transverse instability labelled mushroom instability (MI) was also discovered in PIC simulations regarding the dynamics within the aircraft 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 additionally investigated (Liang et al., 2013a, b, 2017). Alves et al. ESKHI and numerically derived the dispersion relation within the presence of density contrasts or smooth velocity Wood Ranger Power Shears manual (Alves et al., 2014), which are each discovered to stabilize ESKHI. Miller & Rogers (2016) prolonged the theory of ESKHI to finite-temperature regimes by contemplating the strain of electrons and derived a dispersion relation encompassing both ESKHI and MI. In natural eventualities, ESKHI is commonly topic to an external magnetic discipline (Niu et al., 2025; Jiang et al., 2025). However, works mentioned above had been all carried out within the absence of an external magnetic subject. While the speculation of fluid KHI has been prolonged to magnetized flows a long time in the past (Chandrasekhar, 1961; D’Angelo, 1965), the habits of ESKHI in magnetized shear flows has been quite unclear.
So far, the one theoretical issues regarding this problem are presented by Che & Zank (2023) and Tsiklauri (2024). Both works are restricted to incompressible plasmas and some sort of MHD assumptions, Wood Ranger Tools that are only valid for small shear velocities. Therefore, their conclusions can't be immediately applied in the relativistic regime, where ESKHI is anticipated to play a big role (Alves et al., 2014). Simulations had reported clear discrepancies from their idea (Tsiklauri, 2024). As Tsiklauri highlighted, Wood Ranger Tools a derivation of the dispersion relation without excessive assumptions is critical. This kinds a part of the motivation behind our work. On this paper, Wood Ranger Tools we will consider ESKHI below an external magnetic subject by directly extending the works of Gruzinov (2008) and Wood Ranger Power Shears warranty buy Wood Ranger Power Shears cordless power shears Shears order now Alves et al. 2014). Because of this our work is carried out in the limit of cold and collisionless plasma. We adopt the relativistic two-fluid equations and keep away from any type of MHD assumptions. The paper is organized as follows. In Sec. 1, we current a short introduction to the background and subject of ESKHI.