Universal energy cascade and relaxation in three-dimensional inertial electron magnetohydrodynamic turbulence
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arXiv
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| Natura: | Preprint |
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2025
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| _version_ | 1866908444429123584 |
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| author | Banerjee, Supratik Halder, Arijit Das, Amita |
| author_facet | Banerjee, Supratik Halder, Arijit Das, Amita |
| contents | Electron magnetohydrodynamics (EMHD) provides a realistic model for electron-scale heating and acceleration in weakly collisional space plasmas. A divergence-free Banerjee-Galtier type (Banerjee and Galtier, JoPA, 2017) exact relation is derived for three-dimensional homogeneous and not necessarily isotropic EMHD turbulence. By explicit calculation, it has been shown that the energy cascade is not affected by the presence of a uniform background magnetic field Bo. Using direct numerical simulations, a Kolmogorov-like energy cascade with a constant flux rate is observed across the electron inertial scale $d_e$. However, as expected, for length scales greater than $d_e$, a magnetic power spectra of $k^{-7/3}$ is obtained whereas for scales smaller than $d_e$, a $k^{-5/3}$ spectra is obtained. Similar universal cascade rate is also calculated from the scale-by-scale budget in Fourier space and is found to be equal to the one calculated using the exact law in real space. Finally, quenching the turbulence drive, the relaxation of a fully-developed EMHD turbulence is studied using the recently proposed principle of vanishing nonlinear transfers (Banerjee, Halder and Pan, PRE(L), 2023) which convincingly shows the existence of a pressure-balanced relaxed state. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_07628 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Universal energy cascade and relaxation in three-dimensional inertial electron magnetohydrodynamic turbulence Banerjee, Supratik Halder, Arijit Das, Amita Plasma Physics Electron magnetohydrodynamics (EMHD) provides a realistic model for electron-scale heating and acceleration in weakly collisional space plasmas. A divergence-free Banerjee-Galtier type (Banerjee and Galtier, JoPA, 2017) exact relation is derived for three-dimensional homogeneous and not necessarily isotropic EMHD turbulence. By explicit calculation, it has been shown that the energy cascade is not affected by the presence of a uniform background magnetic field Bo. Using direct numerical simulations, a Kolmogorov-like energy cascade with a constant flux rate is observed across the electron inertial scale $d_e$. However, as expected, for length scales greater than $d_e$, a magnetic power spectra of $k^{-7/3}$ is obtained whereas for scales smaller than $d_e$, a $k^{-5/3}$ spectra is obtained. Similar universal cascade rate is also calculated from the scale-by-scale budget in Fourier space and is found to be equal to the one calculated using the exact law in real space. Finally, quenching the turbulence drive, the relaxation of a fully-developed EMHD turbulence is studied using the recently proposed principle of vanishing nonlinear transfers (Banerjee, Halder and Pan, PRE(L), 2023) which convincingly shows the existence of a pressure-balanced relaxed state. |
| title | Universal energy cascade and relaxation in three-dimensional inertial electron magnetohydrodynamic turbulence |
| topic | Plasma Physics |
| url | https://arxiv.org/abs/2507.07628 |