Magnetic reconnection in the auroral acceleration region

Chaston, C. C.

doi:10.1002/2015gl063164

Cited by 10 publications

(13 citation statements)

References 29 publications

(47 reference statements)

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“…The third CS group includes magnetized plasma ( β ≤1) with weak ( M < 1) flows, e.g., plasma from the solar corona [ Allanson et al , ; Priest , ] or the auroral region [ Galperin et al , ; Chaston , , and references therein]. Such weak plasma pressure cannot generate any significant transverse currents; almost all currents are field aligned.…”

Section: Introductionmentioning

confidence: 99%

Mars's magnetotail: Nature's current sheet laboratory

et al. 2017

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The configuration and stability of an important kinetic plasma structure, the current sheet, determine the efficiency of magnetic energy storage, release, and transport in surrounding plasmas. These properties depend on β (the ratio of plasma pressures to magnetic field pressures) and Mach number M (the ratio of bulk velocities to magnetosonic velocities). For the most investigated current sheet, the near‐Earth magnetotail current sheet, these parameters fall within a relatively narrow range of values (high β, low M). To investigate current sheet behavior for a wider range of parameters, we explore current sheets in the magnetotail of Mars using Mars Atmosphere and Volatile Evolution (MAVEN) mission observations. We find that low‐β, high‐M current sheets are abundant in Mars's magnetotail, but high‐β, low‐M current sheets can also be found there. Low‐β current sheets are nearly force‐free, whereas high‐M current sheets are balanced by a plasma flow gradient along the tail. We compare current sheet distributions in a (β,M) space for the Martian magnetotail, the near‐Earth magnetotail (using Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission), and the distant magnetotail (using Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) mission). We also find that the pressure balance in the Martian magnetotail current sheet can occur by contributions from a wide range of ion species, or, in low beta cases, from field‐aligned currents generation of a force‐free magnetic field configuration. The Martian magnetotail is a natural laboratory where current sheet of various types can be found and investigated.

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Section: Introductionmentioning

confidence: 99%

Mars's magnetotail: Nature's current sheet laboratory

et al. 2017

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“…Consistent with this scenario, we suggest that slippage reconnection, the auroral acceleration, and its U ‐shaped potential may be connected. In addition, the observations and the simulation show that guide field magnetic reconnection in a field‐aligned current sheet is likely facilitated by the tearing instability (Chaston, 2015). The reconnection process enhances the auroral acceleration by reducing the shear magnetic stress.…”

Section: Discussionmentioning

confidence: 99%

Magnetic Reconnection in a Sheared Magnetic Flux Tube: Slippage Versus Tearing

et al. 2021

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Magnetic reconnection is a fundamental plasma process that converts magnetic energy to thermal and kinetic energy of the plasma. The earliest work of magnetic reconnection relied on a magnetic field configuration of topologically separate regions (Parker, 1957;Petschek, 1964;Sweet, 1958). Vasyliunas (1975) defined magnetic reconnection as occurring if there existed plasma flows across surfaces that separates regions containing topologically different magnetic field lines. While formally correct in two-dimensional topologies that contain an X-line type topology, this definition was shown to break down in three-dimensional situations where there exists a finite magnetic field component in the third dimension (Schindler et al., 1988). A more general definition, first introduced by Axford (1984), considered the localized breakdown of the frozen-in field (, and the resulting changes in connection as the basis of magnetic reconnection. Due to a non-ideal electric field R localized to a finite diffusion region, plasma elements which are at one time connected by a single magnetic field line are at a later time no longer connected. This concept was adapted and further developed by Schindler et al. (1988) and Hesse and Schindler (1988), who coined the term General Magnetic Reconnection (GMR). They showed that for the most general case of reconnection, where the magnetic field does not vanish inside the diffusion region, termed finite-B reconnection, a necessary condition for magnetic reconnection to be operating, and leading to large scale effects (i.e., not limited to the diffusion region) is the presence of a finite parallel electric potential drop along a set of magnetic field lines passing through the diffusion region, φ ≡∫E ‖ ds ≠ 0. The s is the arc length along this field line.Depending on the nature of this parallel electric field, the reconnection process can be both time-stationary and time-dependent (Hesse et al., 2005). In the time-stationary case, the electric field is potential and the time derivative of the magnetic field vanishes, leading to an effect like magnetic field line sections slipping relative to one another, which breaks magnetic connectivity of plasma elements. In this study, we will refer to the time-stationary case as slippage reconnection. In the time-dependent case, the electric field is inductive, and the time derivative of the magnetic field does not vanish.

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“…FIGURE 4 | Schematic of extreme guide field reconnection and its relation to discrete auroral arc structure (Chaston et al, 2015). Reconnection involves the horizontal magnetic field components.…”

Section: Magnetic Field Topologymentioning

confidence: 99%

“…and Otto and Birk (1993) have suggested that thin, discrete aurora arcs are governed by magnetic reconnection with small magnetic shear. Chaston et al (2015) recently presented the first experimental evidence of the role of extreme guide field reconnection in the auroral acceleration region. Figure 4 summarizes the time sequence of the auroral reconnection process where red and magenta field lines reconnect, giving rise to islands of vorticity in thin auroral arcs (Chaston et al, 2015).…”

Section: Magnetic Field Topologymentioning

confidence: 99%

The Kelvin-Helmholtz Instability From the Perspective of Hybrid Simulations

Delamere

Barnes

2021

Front. Astron. Space Sci.

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The flow shear-driven Kelvin-Helmholtz (KH) instability is ubiquitous in planetary magnetospheres. At Earth these surface waves are important along the dawn and dusk flanks of the magnetopause boundary while at Jupiter and Saturn the entire dayside magnetopause boundary can exhibit KH activity due to corotational flows in the magnetosphere. Kelvin-Helmholtz waves can be a major ingredient in the so-called viscous-like interaction with the solar wind. In this paper, we review the KH instability from the perspective of hybrid (kinetic ions, fluid electrons) simulations. Many of the simulations are based on parameters typically found at Saturn’s magnetopause boundary, but the results can be generally applied to any KH-unstable situation. The focus of the discussion is on the ion kinetic scale and implications for mass, momentum, and energy transport at the magnetopause boundary.

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Magnetic reconnection in the auroral acceleration region

Cited by 10 publications

References 29 publications

Mars's magnetotail: Nature's current sheet laboratory

Mars's magnetotail: Nature's current sheet laboratory

Magnetic Reconnection in a Sheared Magnetic Flux Tube: Slippage Versus Tearing

The Kelvin-Helmholtz Instability From the Perspective of Hybrid Simulations

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