Perspectives on magnetic reconnection

Zweibel, Ellen G.; Yamada, Masaaki

doi:10.1098/rspa.2016.0479

Cited by 87 publications

(82 citation statements)

References 117 publications

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“…The solid, red lines indicate the trajectories of plasma elements, which are given by ∫ V ( t )d t . The line integral was performed backward in time from the onset t = 57.3 min to t = 52.3 min. The plasma originating in the lobe (inflow region) traverses separatrix as the magnetic field reconnects, and moves to the outflow region, as shown in Figure of Eastwood et al () and Figure of Zweibei and Yamada (). Only the earthward flow is shown in Figure a.…”

Section: Resultsmentioning

confidence: 99%

Energy Flow Exciting Field‐Aligned Current at Substorm Expansion Onset

Ebihara

Tanaka

2017

JGR Space Physics

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At substorm expansion onset, upward field‐aligned currents (FACs) increase abruptly, and a large amount of electromagnetic energy starts to consume in the polar ionosphere. A question arises as to where the energy comes from. Based on the results obtained by the global magnetohydrodynamics simulation, we present energy flow and energy conversion associated with the upward FACs that manifest the onset. Our simulations show that the cusp/mantle region transmits electromagnetic energy to almost the entire region of the magnetosphere when the interplanetary magnetic field is southward. Integral curve of the Poynting flux shows a spiral moving toward the ionosphere, probably suggesting the pathway of electromagnetic energy from the cusp/mantle dynamo to the ionosphere. The near‐Earth reconnection initiates three‐dimensional redistribution of the magnetosphere. Flow shear in the near‐Earth region results in the generation of the near‐Earth dynamo and the onset FACs. The onset FACs are responsible to transport the electromagnetic energy toward the Earth. In the near‐Earth region, the electromagnetic energy coming from the cusp/mantle dynamo is converted to the kinetic energy (known as bursty bulk flow) and the thermal energy (associated with high‐pressure region in the inner magnetosphere). Then, they are converted to the electromagnetic energy associated with the onset FACs. A part of electromagnetic energy is stored in the lobe region during the growth phase. The release of the stored energy, together with the continuously supplied energy from the cusp/mantle dynamo, contributes to the energy supply to the ionosphere during the expansion phase.

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Section: Resultsmentioning

confidence: 99%

Energy Flow Exciting Field‐Aligned Current at Substorm Expansion Onset

Ebihara

Tanaka

2017

JGR Space Physics

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“…2 and references therein. These in-plane currents contribute to the reconnecting electric field through the Hall term, J×B/en e , which is known to play a dominant role in collisionless plasmas.…”

Section: δmentioning

confidence: 99%

“…Magnetic reconnection plays a fundamental role in plasma physics, as it provides a mechanism to break the frozen-in condition which constrains the magnetic field and the plasma to move together 1,2 . As such, reconnection is a powerful influence on the dynamics and structure of the plasma which makes up the majority of the visible matter in the universe.…”

Section: Introductionmentioning

confidence: 99%

Formation and structure of a current sheet in pulsed-power driven magnetic reconnection experiments

et al. 2017

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We describe magnetic reconnection experiments using a new, pulsed-power driven experimental platform in which the inflows are super-sonic but sub-Alfvénic. The intrinsically magnetised plasma flows are long lasting, producing a well-defined reconnection layer that persists over many hydrodynamic time scales. The layer is diagnosed using a suite of high resolution laser based diagnostics which provide measurements of the electron density, reconnecting magnetic field, inflow and outflow velocities and the electron and ion temperatures. Using these measurements we observe a balance between the power flow into and out of the layer, and we find that the heating rates for the electrons and ions are significantly in excess of the classical predictions. The formation of plasmoids is observed in laser interferometry and optical self-emission, and the magnetic O-point structure of these plasmoids is confirmed using magnetic probes.

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“…Exploring the dynamics of magnetized plasmas in the range of scales extending from the ion to the electron Larmor radii (hereafter denoted ρ i and ρ e respectively) is of great importance in various contexts, including magnetic reconnection (Daughton et al 2011;Treumann & Baumjohann 2013;Zweibel & Yamada 2017) and turbulence in space plasmas such as the solar wind (Sahraoui et al 2010(Sahraoui et al , 2013Matteini et al 2017) or the auroral regions (Chaston et al 2008). At scales comparable to or smaller than the electron inertial length d e , electron inertia cannot be neglected, while electron finite Larmor radius (FLR) corrections play a role at scales approaching ρ e .…”

Section: Introductionmentioning

confidence: 99%

Electron-scale reduced fluid models with gyroviscous effects

2017

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Reduced fluid models for collisionless plasmas including electron inertia and finite Larmor radius corrections are derived for scales ranging from the ion to the electron gyroradii. Based either on pressure balance or on the incompressibility of the electron fluid, they respectively capture kinetic Alfvén waves (KAWs) or whistler waves (WWs), and can provide suitable tools for reconnection and turbulence studies. Both isothermal regimes and Landau fluid closures permitting anisotropic pressure fluctuations are considered. For small values of the electron beta parameter β e , a perturbative computation of the gyroviscous force valid at scales comparable to the electron inertial length is performed at order O(β e ), which requires second-order contributions in a scale expansion. Comparisons with kinetic theory are performed in the linear regime. The spectrum of transverse magnetic fluctuations for strong and weak turbulence energy cascades is also phenomenologically predicted for both types of waves. In the case of moderate ion to electron temperature ratio, a new regime of KAW turbulence at scales smaller than the electron inertial length is obtained, where the magnetic energy spectrum decays like k −13/3 ⊥ , thus faster than the k −11/3 ⊥ spectrum of WW turbulence.

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Perspectives on magnetic reconnection

Cited by 87 publications

References 117 publications

Energy Flow Exciting Field‐Aligned Current at Substorm Expansion Onset

Energy Flow Exciting Field‐Aligned Current at Substorm Expansion Onset

Formation and structure of a current sheet in pulsed-power driven magnetic reconnection experiments

Electron-scale reduced fluid models with gyroviscous effects

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