Towards understanding magnetic holes: Hybrid simulations

Baumgärtel, K.; Sauer, K.; Dubinin, E.

doi:10.1029/2003gl017373

Cited by 42 publications

(64 citation statements)

References 23 publications

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“…4 This appears to be tied to a bistability phenomenon, whereby nonlinear mirror structures which are magnetic holes can exist in a plasma which is below the mirror linear instability threshold. This behavior is found in both simulations 9 and fluid models based on anisotropic MHD with a Landau fluid closure. 10 Observations of magnetic holes in the solar wind and magnetosheath are consistent with them being non-propagating structures, such as mirror structures, but would be incompatible with dark soliton solutions of the Hall-MHD system.…”

Section: Introductionmentioning

confidence: 77%

Electron vortex magnetic holes: A nonlinear coherent plasma structure

et al. 2015

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We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 77%

Electron vortex magnetic holes: A nonlinear coherent plasma structure

et al. 2015

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“…[3] In recent years, an alternative, ''soliton'' approach to magnetic holes, and other nonlinear structures observed in the magnetosheath of planets and comets has been developed in a series of articles by Baumgärtel [1999], Baumgärtel et al [2003], Sauer et al [2003], , and Dubinin et al [2003]. By using two-or multi-fluid equations and hybrid simulations these authors have found a variety of solitary solutions that could explain many of the reported experimental results.…”

Section: Introductionmentioning

confidence: 99%

Reinterpretation of mirror modes as trains of slow magnetosonic solitons

Stasiewicz

2004

Geophysical Research Letters

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[1] It is shown that large amplitude periodic oscillations of the magnetic field measured frequently by spacecraft in the magnetosheath, and interpreted as mirror-mode waves/ structures, represent trains of slow-mode magnetosonic solitons. Nonlinear magnetosonic wave-trains with properties attributed previously to mirror-mode structures are obtained as exact solutions of Hall-MHD equations with anisotropic ion pressure. The theoretically derived properties of magnetosonic solitons are compared with multipoint measurements on Cluster satellites in the magnetosheath with plasma beta (plasma/magnetic pressure) $10. The computed properties of nonlinear waves: amplitudes, spatial scales, periodicity, and propagation velocities are consistent with in situ measurements in space.

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“…Observations and numerical simulations have shown that magnetic peaks are rarely seen in mirror stable plasma because of their rapid decay, but magnetic holes could survive in a mirror stable plasma. Therefore, both peaks and holes could be observed in the magnetosheath, and most holes are observed near the magnetopause, where the plasma is mirror stable (Baumgartel et al, 2003;Travnicek et al, 2007;Soucek et al, 2008;Génot et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…They therefore suggested that LMHs are probably the remnants of mirror modes structures in the solar wind (see also Winterhalter et al, 1995;Russell et al, 2008;Zhang et al, 2008Zhang et al, , 2009). Many other mechanisms have been proposed to explain the magnetic holes in the solar wind, such as the soliton approach (Baumgartel, 1999;Baumgartel et al, 2003), and theories associated with Alfvén waves (see, for example, Buti et al, 2001;Tsurutani et al, 2005). The stable solitons correspond to isotropic plasma with high β and their propagation direction is close to perpendicular to the ambient magnetic field vector.…”

Section: Introductionmentioning

confidence: 99%

Cluster and TC-1 observation of magnetic holes in the plasma sheet

Sun

Shi

et al. 2012

Ann. Geophys.

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Abstract. Magnetic holes with relatively small scale sizes, detected by Cluster and TC-1 in the magnetotail plasma sheet, are studied in this paper. It is found that these magnetic holes are spatial structures and they are not magnetic depressions generated by the flapping movement of the magnetotail current sheet. Most of the magnetic holes (93 %) were observed during intervals with B z larger than B x , i.e. they are more likely to occur in a dipolarized magnetic field topology. Our results also suggest that the occurrence of these magnetic holes might have a close relationship with the dipolarization process. The magnetic holes typically have a scale size comparable to the local proton Larmor radius and are accompanied by an electron energy flux enhancement at a 90 • pitch angle, which is quite different from the previously observed isotropic electron distributions inside magnetic holes in the plasma sheet. It is also shown that most of the magnetic holes occur in marginally mirror-stable environments. Whether the plasma sheet magnetic holes are generated by the mirror instability related to ions or not, however, is unknown. Comparison of ratios, scale sizes and propagation direction of magnetic holes detected by Cluster and TC-1, suggests that magnetic holes observed in the vicinity of the TC-1 orbit (∼7-12 R E ) are likely to be further developed than those observed by Cluster (∼7-18 R E ).

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Towards understanding magnetic holes: Hybrid simulations

Cited by 42 publications

References 23 publications

Electron vortex magnetic holes: A nonlinear coherent plasma structure

Electron vortex magnetic holes: A nonlinear coherent plasma structure

Reinterpretation of mirror modes as trains of slow magnetosonic solitons

Cluster and TC-1 observation of magnetic holes in the plasma sheet

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