A new approach to the linear theory of single‐species tearing in two‐dimensional quasi‐neutral sheets

Brittnacher, M.; Quest, K. B.; Karimabadi, H.

doi:10.1029/94ja02743

Cited by 53 publications

(65 citation statements)

References 27 publications

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“…In an analytic study, Brittnacher et al (1995) showed that when ρ i /w 0 ≈ 1, the fastest growing linear mode occurs at kw 0 ≈ 0.5, where k is the wavenumber of the tearing mode, w 0 is the halfwidth of the current sheet, and ρ i is the ion gyroradius. Since…”

Section: Introductionmentioning

confidence: 99%

The Effects of Plasma Beta and Anisotropy Instabilities on the Dynamics of Reconnecting Magnetic Fields in the Heliosheath

Schoeffler

Drake

Swisdak

2011

ApJ

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The plasma β (the ratio of the plasma pressure to the magnetic pressure) of a system can have a large effect on its dynamics as high β enhances the effects of pressure anisotropies. We investigate the effects of β in a system of stacked current sheets that break up into magnetic islands due to magnetic reconnection, which is analogous to the compressed heliospheric current sheet in the heliosheath. We find significant differences between systems with low and high initial values of β. At low β, growing magnetic islands are modestly elongated and become round as contraction releases magnetic stress and reduces magnetic energy. At high β, the increase of the parallel pressure in contracting islands causes saturation of modestly elongated islands as island cores approach the marginal firehose condition. Only highly elongated islands reach finite size. The anisotropy within these islands prevents full contraction, leading to a final state of highly elongated islands in which further reconnection is suppressed. The elongation of islands at finite β is further enhanced by reducing the electron-to-ion mass ratio to more realistic values. The results are directly relevant to reconnection in the sectored region of the heliosheath where there is evidence that elongated islands are present, and possibly to other high-β systems such as astrophysical accretion flows and the magnetosphere of Saturn.

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Section: Introductionmentioning

confidence: 99%

The Effects of Plasma Beta and Anisotropy Instabilities on the Dynamics of Reconnecting Magnetic Fields in the Heliosheath

Schoeffler

Drake

Swisdak

2011

ApJ

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“…] in the normalized unit, with L x = 12D (the wavelength of the fastest growing mode [Brittnacher et al, 1995]), L y = 0.5, and L z = 8D. The choice of L y = 0.5 excludes any longerwave drift modes, such as the drift-kink instability (DKI) and the drift-sausage instability (DSI) [e.g., Ozaki et al, 1996;Lapenta and Brackbill, 1997;Horiuchi and Sato, 1999], from the present study.…”

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confidence: 99%

Quick magnetic reconnection triggering in an ion‐scale current sheet: Transition from Type‐I to Type‐II

Tanaka

Shinohara

Fujimoto

2005

Geophysical Research Letters

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The details of Quick Magnetic Reconnection Triggering (QMRT) in ion‐scale current sheets have been investigated using three‐dimensional (3‐D) full particle simulations with the mass ratio of 400. QMRT is mediated by coupling to the Lower‐Hybrid Drift Instability (LHDI) and its time scale is as quick as the LHDI time scale. Up to the initial half‐thickness D of D/λi = 0.875 (λi: the ion inertial length), QMRT is attained via thin current layer formation at the center of the current sheet in reaction to the LHDI activity (Type‐I). At D/λi = 1, QMRT is still available but is attained by boosting up the tearing instability growth rate via the electron temperature anisotropy Te⊥/Te∥ ∼ 1.2 (Type‐II). In this case the LHDI activity induces the current density redistribution that does not result in enhanced current density at the center but produces electron perpendicular heating therein.

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“…(4.14) from the approximate theory, and is compared in Fig. F21 with the analytical theory by Brittnacher et al (1995) and the full orbit approach. The current sheet for this comparison is an isotropic pair-plasma Harris type with ρ i /L = 1, T ⊥i /T ⊥e = 1, n b /n 0 = 0.…”

Section: Electron-positron Harris Sheetmentioning

confidence: 99%

Kinetic theory and simulation of collisionless tearing in bifurcated current sheets

Matsui

Daughton

2008

Physics of Plasmas

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Observations from the Earth's geomagnetic tail have established that the current sheet is often bifurcated with two peaks in the current density. These so-called bifurcated current sheets have also been reported in a variety of simulations and often occur in conjunction with significant temperature anisotropy. In this work, a new self-consistent Vlasov equilibrium is developed that permits both the current profile and temperature anisotropy to be independently adjusted. This new equilibrium has a sufficient flexibility to model a wide variety of bifurcated sheets observed in both kinetic simulations and space observations, and transforms continuously back to the standard Harris sheet model with a single peak in the current density. The linear stability of these layers with respect to the tearing mode is examined in the framework of resistive MHD and full Vlasov theory. From the simplified fluid theory, it is demonstrated that a bifurcated current profile has a stabilizing influence on the resistive tearing instability. However, the resistive MHD model is not really appropriate to model the highly collisionless plasma conditions in the magnetosphere. To obtain reliable predictions, Vlasov theory is required and the approach in this thesis employs both standard analytic techniques and a formally exact treatment in which the full orbit integral is numerically evaluated. The resulting linear growth rate for the collisionless tearing instability and the mode structure are verified with 2D full kinetic particle-in-cell simulations. The simplified analytic theory is reasonably accurate in capturing these dependencies for long wavelength modes, but the short wavelength 2 regime generally requires the full numerical treatment to accurately compute the growth rate. The results from these different approaches consistently demonstrate that a bifurcated current profile has a strong stabilizing influence on the collisionless tearing mode in comparison to centrally peaked layers with a similar thickness. In collisionless tearing, electron temperature anisotropy is strongly destabilizing in the limit T e⊥ > T e and strongly stabilizing when T e⊥ < T e . Thus, the collisionless tearing instability is determined by the competition between these two influences.

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A new approach to the linear theory of single‐species tearing in two‐dimensional quasi‐neutral sheets

Cited by 53 publications

References 27 publications

The Effects of Plasma Beta and Anisotropy Instabilities on the Dynamics of Reconnecting Magnetic Fields in the Heliosheath

The Effects of Plasma Beta and Anisotropy Instabilities on the Dynamics of Reconnecting Magnetic Fields in the Heliosheath

Quick magnetic reconnection triggering in an ion‐scale current sheet: Transition from Type‐I to Type‐II

Kinetic theory and simulation of collisionless tearing in bifurcated current sheets

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