Structure of reconnection layers in the magnetosphere

Lin, Y.; Lee, L. C.

doi:10.1007/bf00749762

Cited by 151 publications

(151 citation statements)

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“…Dynamics are followed beginning with the bent tube that would result from completed reconnection. The subsequent dynamical evolution is a TFT Riemann problem in which, like its MHD counterpart (Lin & Lee 1994), the initial bend decomposes into a set of propagating shocks, surrounding a central region compressed and heated by slow shocks. When Rankine-Hugoniot relations are invoked at the TFT shocks, their properties roughly approximate those from steady Petschek models , as indicated by the solid lines in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Longcope

Klimchuk

2015

ApJ

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Aspects of solar flare dynamics, such as chromospheric evaporation and flare lightcurves, have long been studied using one-dimensional models of plasma dynamics inside a static flare loop, subjected to some energy input. While extremely successful at explaining the observed characteristics of flares, all such models so far have specified energy input ad hoc, rather than deriving it self-consistently. There is broad consensus that flares are powered by magnetic energy released through reconnection. Recent work has generalized Petschek's basic reconnection scenario, topological change followed by field line retraction and shock heating, to permit its inclusion ina onedimensional flare loop model. Here we compare the gas dynamics driven by retraction and shocking to those from more conventional static loop models energized by ad hoc source terms. We find significant differences during the first minute, when retraction leads to larger kinetic energies and produces higher densities at the loop top, while ad hoc heating tends to rarify the loop top. The loop-top density concentration is related to the slow magnetosonic shock, characteristic of Petschek's model, but persists beyond the retraction phase occurring in the outflow jet. This offers an explanation for observed loop-top sources of X-ray and EUV emission, with advantages over that provided by ad hoc heating scenarios. The cooling phases of the two models are, however, notably similar to one another, suggesting that observations at that stage will yield little information on the nature of energy input.

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Section: Introductionmentioning

confidence: 99%

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Longcope

Klimchuk

2015

ApJ

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“…On the other hand, simultaneous appearance of a fast plasma flow and thin current sheets was described by the theory of the so called "reconnection layer" (Lin and Lee, 1994). The solution of the Riemann problem on decay of an arbitrary MHD discontinuity was extended to the case of collisionless plasma by means of numerical particle simulations using a hybrid code.…”

Section: May Be the Proper Candidate But What Is Their Origin?mentioning

confidence: 99%

“…Underlying assumption is that at some locations on the thin CS, abrupt losses of equilibrium occur, and they are later followed with much slower relaxation of the out-of-equilibrium system thus arising. In earlier simulation (Lin and Lee, 1994), such an evolution could involve the Hall effect and generation of magnetic field y-component, which produces formation, among others, of rotational discontinuity-like structures. However, at ρ 1 /ρ 0 1, the CS evolution is slow enough that the Hall effects may be neglected (see Domrin and Kropotkin, 2007c).…”

Section: Relaxation Of the Quasi-one-dimensional Thin Cs And Magneticmentioning

confidence: 99%

“…We thus obtained two versions of "reconnection layer" (Lin and Lee, 1994) formation. At the medium scale level in the geomagnetic tail, this dynamics presents spontaneous process of magnetic field merging; the magnetic field flux and energy are brought inside by a pair of MHD self-similar rarefaction waves propagating over the background plasma from the nonlinear structure which has formed.…”

Section: Relaxation Of the Quasi-one-dimensional Thin Cs And Magneticmentioning

confidence: 99%

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Kinetic thin current sheets: their formation in relation to magnetotail mesoscale turbulent dynamics

Kropotkin

Domrin

2009

Ann. Geophys.

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Abstract. Dynamics of the magnetotail plasma sheet (PS) features nonlinear structures on two totally different scales. There are very thin current sheets (CS) on kinetic scale of the ion gyroradius. And there are intense plasma flow and magnetic field variations on mesoscales (a few earth radii); those are interpreted as mostly 2-D MHD turbulence. On the other hand, the specific nature of slow large scale magnetotail evolution leads to large differences in the PS properties and those of the lobe plasma. As a result, while fast reconnection bursts in the tail provide quasi-stationary fast mesoscale reconfigurations in the lobes, they cannot however be accompanied by restructuring of CS on the same fast time scale. Violations of force balance in the PS are thus generated. Simulation using a hybrid code and starting with such imbalance, provides an evidence of very thin kinetic CS structures formation, embedded into the much thicker PS. The momentum balance gets locally restored by means of ion acceleration up to the Alfvénic velocity. The process provides an effective mechanism for transformation of magnetic energy accumulated in the magnetotail, into energy of plasma flows. The fast flows may drive turbulence on shorter spatial scales. In their turn, these motions may serve as an origin for new neutral line generation, and reconnection. Application to substorm phenomenology is discussed.

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“…We do not agree with the statement that "little was known about asymmetric reconnection until recently" 3 because several parts, in particular, stress balance, have been studied in detail in the past. [5][6][7][8][10][11][12] Physically, as can be seen from Eq. ͑10͒, there is an Alfvén wave standing in the inflow and as a consequence, Alfvén and plasma velocities are related by stress balance as given by Eq.…”

Section: ͑14͒mentioning

confidence: 99%

Comment on “Scaling of asymmetric magnetic reconnection: General theory and collisional simulations” [Phys. Plasmas 14, 102114 (2007)]

2009

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Structure of reconnection layers in the magnetosphere

Abstract: 2.1 Magnetohydrodynamic (MHD) Discontinuities 2.2 Variation of Physical Quantities Across Expansion Waves 2.3 Formulation of the Riemann Problem 31 2.4 Structure of the Reconnection Layer in Cases with B y = 0 2.5 Structure of the Reconnection Layer in Cases with B y ^ 0

Cited by 151 publications

References 137 publications

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Kinetic thin current sheets: their formation in relation to magnetotail mesoscale turbulent dynamics

Comment on “Scaling of asymmetric magnetic reconnection: General theory and collisional simulations” [Phys. Plasmas 14, 102114 (2007)]

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