Electron-scale Kelvin-Helmholtz Instability in Magnetized Shear Flows > 자유게시판

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Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are found in several astrophysical situations. Naturally ESKHI is topic to a background magnetic area, but an analytical dispersion relation and an accurate development fee of ESKHI under this circumstance are long absent, as former MHD derivations usually are not applicable in the relativistic regime. We current a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with few assumptions. ESKHI linear development rates in certain instances are numerically calculated. We conclude that the presence of an exterior magnetic discipline decreases the maximum instability growth fee usually, but can barely improve it when the shear velocity is sufficiently excessive. Also, the exterior magnetic discipline results in a bigger cutoff wavenumber of the unstable band and will increase the wavenumber of the most unstable mode. PIC simulations are carried out to confirm our conclusions, where we also observe the suppressing of kinetic DC magnetic discipline era, ensuing from electron gyration induced by the exterior magnetic field. Electron-scale Kelvin-Helmholtz instability (ESKHI) is a shear instability that takes place at the shear boundary the place a gradient in velocity is current.

Despite the significance of shear instabilities, ESKHI was solely acknowledged recently (Gruzinov, 2008) and stays to be largely unknown in physics. KHI is stable underneath a such condition (Mandelker et al., Wood Ranger Power Shears website 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, buy Wood Ranger Power Shears the place he also derived the analytical dispersion relation of ESKHI growth price 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 discipline. It's noteworthy that PIC simulations also discovered the generation of a DC magnetic discipline (whose average along the streaming route just isn't zero) in company with the AC magnetic field induced by ESKHI, while the previous just isn't predicted by Gruzinov. The era of DC magnetic fields is due to electron thermal diffusion or mixing induced by ESKHI throughout the shear interface (Grismayer et al., 2013), which is a kinetic phenomenon inevitable within the settings of ESKHI.

A transverse instability labelled mushroom instability (MI) was additionally discovered in PIC simulations regarding the dynamics within the plane 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, Wood Ranger Power Shears website 2017). Alves et al. ESKHI and numerically derived the dispersion relation in the presence of density contrasts or easy velocity Wood Ranger Power Shears website (Alves et al., 2014), that are each found to stabilize ESKHI. Miller & Rogers (2016) prolonged the idea of ESKHI to finite-temperature regimes by considering the stress of electrons and derived a dispersion relation encompassing each ESKHI and MI. In natural scenarios, ESKHI is commonly subject to an external magnetic area (Niu et al., Wood Ranger Power Shears review Wood Ranger Power Shears order now Wood Ranger Power Shears order now Wood Ranger Power Shears features website 2025; Jiang et al., 2025). However, works mentioned above have been all carried out in the absence of an external magnetic subject. While the theory of fluid KHI has been extended to magnetized flows a long time in the past (Chandrasekhar, 1961; D’Angelo, Wood Ranger Power Shears website 1965), Wood Ranger Power Shears website the conduct of ESKHI in magnetized shear flows has been quite unclear.

So far, the only theoretical considerations regarding this problem are offered by Che & Zank (2023) and Tsiklauri (2024). Both works are limited to incompressible plasmas and a few form of MHD assumptions, that are only valid for small shear velocities. Therefore, their conclusions cannot be immediately utilized within the relativistic regime, the place ESKHI is predicted to play a big position (Alves et al., 2014). Simulations had reported clear discrepancies from their principle (Tsiklauri, 2024). As Tsiklauri highlighted, a derivation of the dispersion relation without extreme assumptions is critical. This kinds a part of the motivation behind our work. On this paper, we will consider ESKHI below an external magnetic field by straight extending the works of Gruzinov (2008) and Alves et al. 2014). Because of this our work is carried out within the restrict of cold and Wood Ranger Power Shears website 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 topic of ESKHI.