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

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Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are present in several astrophysical situations. Naturally ESKHI is subject to a background magnetic discipline, however an analytical dispersion relation and an accurate growth rate of ESKHI beneath this circumstance are lengthy absent, as former MHD derivations usually are not applicable within the relativistic regime. We present a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with few assumptions. ESKHI linear development rates in certain cases are numerically calculated. We conclude that the presence of an external magnetic subject decreases the utmost instability progress charge typically, but can barely enhance it when the shear velocity is sufficiently excessive. Also, the exterior magnetic area ends in a bigger cutoff wavenumber of the unstable band and will increase the wavenumber of essentially the most unstable mode. PIC simulations are carried out to confirm our conclusions, where we additionally observe the suppressing of kinetic DC magnetic field generation, resulting from electron gyration induced by the external magnetic subject. 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 significance of shear instabilities, ESKHI was solely acknowledged just lately (Gruzinov, 2008) and remains to be largely unknown in physics. KHI is stable beneath a such situation (Mandelker et al., Wood Ranger Power Shears USA shears 2016). These make ESKHI a promising candidate to generate magnetic fields in the relativistic jets. ESKHI was first proposed by Gruzinov (2008) in the restrict of a cold and collisionless plasma, where he additionally derived the analytical dispersion relation of ESKHI progress charge for symmetrical shear flows. PIC simulations later confirmed the existence of ESKHI (Alves et al., wood shears Wood Ranger Power Shears for sale Wood Ranger Power Shears coupon Wood Ranger Power Shears review coupon 2012), finding the generation of typical electron vortexes and Wood Ranger official magnetic field. It is noteworthy that PIC simulations additionally found the technology of a DC magnetic discipline (whose common alongside the streaming route is not zero) in company with the AC magnetic field induced by ESKHI, while the previous is just not predicted by Gruzinov. The technology of DC magnetic fields is due to electron thermal diffusion or mixing induced by ESKHI across 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 found in PIC simulations concerning the dynamics in 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 additionally investigated (Liang et al., Wood Ranger official 2013a, Wood Ranger official b, 2017). Alves et al. ESKHI and numerically derived the dispersion relation in the presence of density contrasts or easy velocity shears (Alves et al., 2014), which are each discovered to stabilize ESKHI. Miller & Rogers (2016) extended the theory of ESKHI to finite-temperature regimes by contemplating the pressure of electrons and derived a dispersion relation encompassing both ESKHI and MI. In pure situations, ESKHI is often subject to an external magnetic area (Niu et al., 2025; Jiang et al., 2025). However, works talked about above were all carried out in the absence of an exterior magnetic area. While the speculation of fluid KHI has been extended to magnetized flows a very long time in the past (Chandrasekhar, 1961; D’Angelo, Wood Ranger official 1965), the behavior of ESKHI in magnetized shear flows has been relatively unclear.

To this point, the only theoretical concerns regarding this drawback are presented by Che & Zank (2023) and Tsiklauri (2024). Both works are restricted to incompressible plasmas and some type of MHD assumptions, which are solely valid for small shear velocities. Therefore, their conclusions cannot be instantly applied within the relativistic regime, Wood Ranger official where ESKHI is predicted to play a big 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 excessive assumptions is necessary. This varieties part of the motivation behind our work. In this paper, we are going to consider ESKHI under an exterior magnetic area by straight extending the works of Gruzinov (2008) and Alves et al. 2014). This means that our work is carried out within the limit of cold and collisionless plasma. We undertake the relativistic two-fluid equations and Wood Ranger official keep away from any form of MHD assumptions. The paper is organized as follows. In Sec. 1, we current a brief introduction to the background and subject of ESKHI.