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

Electron-scale Kelvin-Helmholtz instabilities (ESKHI) are present in a number of astrophysical scenarios. Naturally ESKHI is subject to a background magnetic subject, however an analytical dispersion relation and an accurate growth rate of ESKHI underneath this circumstance are lengthy absent, as former MHD derivations will not be relevant within the relativistic regime. We present a generalized dispersion relation of ESKHI in relativistic magnetized shear flows, with few assumptions. ESKHI linear growth rates in sure instances are numerically calculated. We conclude that the presence of an exterior magnetic subject decreases the maximum instability development price in most cases, but can slightly 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 increases the wavenumber of essentially the most unstable mode. PIC simulations are carried out to confirm our conclusions, the place we additionally observe the suppressing of kinetic DC magnetic field era, ensuing from electron gyration induced by the external magnetic area. Electron-scale Kelvin-Helmholtz instability (ESKHI) is a shear instability that takes place on the shear boundary where a gradient in velocity is present.

Despite the significance of shear instabilities, ESKHI was solely acknowledged not too long ago (Gruzinov, 2008) and stays to be largely unknown in physics. KHI is stable underneath a such situation (Mandelker et al., 2016). These make ESKHI a promising candidate to generate magnetic fields in the relativistic jets. ESKHI was first proposed by Gruzinov (2008) within the restrict of a cold and collisionless plasma, Wood Ranger Power Shears official site the place he also derived the analytical dispersion relation of ESKHI progress price for symmetrical shear flows. PIC simulations later confirmed the existence of ESKHI (Alves et al., outdoor trimming tool 2012), finding the era of typical electron vortexes and magnetic area. It's noteworthy that PIC simulations additionally found the technology of a DC magnetic subject (whose average along the streaming course shouldn't be zero) in firm with the AC magnetic field induced by ESKHI, while the previous will not be predicted by Gruzinov. The generation of DC magnetic fields is due to electron thermal diffusion or mixing induced by ESKHI across the shear interface (Grismayer et al., 2013), Wood Ranger Power Shears official site which is a kinetic phenomenon inevitable within the settings of ESKHI.

A transverse instability labelled mushroom instability (MI) was additionally discovered in PIC simulations concerning 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 additionally investigated (Liang et al., 2013a, Wood Ranger Power Shears official site b, 2017). Alves et al. ESKHI and garden power shears numerically derived the dispersion relation within the presence of density contrasts or clean velocity Wood Ranger Power Shears official site (Alves et al., 2014), which are both discovered to stabilize ESKHI. Miller & Rogers (2016) extended the speculation of ESKHI to finite-temperature regimes by contemplating the pressure of electrons and Wood Ranger Power Shears manual derived a dispersion relation encompassing both ESKHI and Wood Ranger Power Shears official site MI. In pure situations, ESKHI is commonly topic to an exterior magnetic area (Niu et al., Wood Ranger Power Shears 2025; Jiang et al., 2025). However, works talked about above had been all carried out within the absence of an external magnetic field. While the theory of fluid KHI has been extended to magnetized flows a long time in the past (Chandrasekhar, 1961; D’Angelo, 1965), the conduct of ESKHI in magnetized shear flows has been rather unclear.

So far, the only theoretical concerns concerning this drawback are offered by Che & Zank (2023) and Tsiklauri (2024). Both works are restricted to incompressible plasmas and some form of MHD assumptions, that are only valid for small shear velocities. Therefore, their conclusions cannot be immediately applied in the relativistic regime, the place ESKHI is anticipated to play a major role (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 important. This kinds part of the motivation behind our work. In this paper, we'll consider ESKHI under an exterior magnetic area by instantly 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 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, Wood Ranger Power Shears we current a brief introduction to the background and topic of ESKHI.