Reconnection Rate for the Inhomogeneous Resistivity Petschek Model

Еркаев, Н. В.; Semenov, V. S.; Jamitzky, Ferdinand

doi:10.1103/physrevlett.84.1455

Cited by 49 publications

(42 citation statements)

References 12 publications

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“…Petschek-like scale separation has therefore been identified as a necessary ingredient for any magnetic reconnection mechanism to work at Alfvénic speeds (Birn et al 2001;Biskamp & Schwarz 2001;Forbes et al 2013), which the Sweet-Parker model famously fails to do. Moreover, when this scale separation does obtain, the structure on the large scales is found to approximate that of Petschek's model (Biernat et al 1987;Heyn & Semenov 1996;Erkaev et al 2000). While the details of the diffusion region remain unclear theoretically, we hereafter use the observational fact of fast flare reconnection to posit that some localized mechanism must be at work, and that the large-scale response will therefore have a Petschek-like structure.…”

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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“…This seems to imply that Petschek-type reconnection is possible only if the resis- tivity of the plasma is localized to a small region, whereas for constant resistivity, the Sweet-Parker regime is realized (Erkaev et al, 2000). Figure 9 shows the normalized diffusion region electric field (top) and length scale (bottom) as functions of the parameter f .…”

Section: Results Of the Numerical Simulationmentioning

confidence: 99%

“…For the diffusion region, it seems to be impossible to find an analytical solution, and hence a solution has to be obtained numerically (Erkaev et al, 2000). The reconnection rate can be determined by matching the solutions corresponding to the diffusion and convective regions.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional MHD model of the reconnection diffusion region

Еркаев

Семенов

Biernat

2002

Nonlin. Processes Geophys.

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Abstract. Magnetic reconnection is an important process providing a fast conversion of magnetic energy into thermal and kinetic plasma energy. In this concern, a key problem is that of the resistive diffusion region where the reconnection process is initiated. In this paper, the diffusion region is associated with a nonuniform conductivity localized to a small region. The nonsteady resistive incompressible MHD equations are solved numerically for the case of symmetric reconnection of antiparallel magnetic fields. A Petschek type steady-state solution is obtained as a result of time relaxation of the reconnection layer structure from an arbitrary initial stage. The structure of the diffusion region is studied for various ratios of maximum and minimum values of the plasma resistivity. The effective length of the diffusion region and the reconnection rate are determined as functions of the length scale and the maximum of the resistivity. For sufficiently small length scale of the resistivity, the reconnection rate is shown to be consistent with Petschek's formula. By increasing the resistivity length scale and decreasing the resistivity maximum, the reconnection layer tends to be wider, and correspondingly, the reconnection rate tends to be more consistent with that of the Parker-Sweet regime.

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“…It was shown later that spatial non-uniform resistivity is required to support the Petschek type scenario (e.g. Sato and Hayashi, 1979;Biskamp, 1986;Erkaev et al, 2000;Biskamp and Schwarz, 2001;Erkaev et al, 2002). This anomalous resistivity in collisionless plasmas may be caused by microinstabilities, such as the lower hybrid drift instability (Huba et al, 1977), the Buneman instability (Drake et al, 2003), the ion-acoustic instability (Kan, 1971;Coroniti, 1985), or others (Büchner and Daughton, 2007).…”

Section: Fast Reconnectionmentioning

confidence: 99%

Collisionless magnetic reconnection: analytical model and PIC simulation comparison

et al. 2009

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Abstract. Magnetic reconnection is believed to be responsible for various explosive processes in the space plasma including magnetospheric substorms. The Hall effect is proved to play a key role in the reconnection process. An analytical model of steady-state magnetic reconnection in a collisionless incompressible plasma is developed using the electron Hall MHD approximation. It is shown that the initial complicated system of equations may split into a system of independent equations, and the solution of the problem is based on the Grad-Shafranov equation for the magnetic potential. The results of the analytical study are further compared with a two-dimensional particle-in-cell simulation of reconnection. It is shown that both methods demonstrate a close agreement in the electron current and the magnetic and electric field structures obtained. The spatial scales of the acceleration region in the simulation and the analytical study are of the same order. Such features like particles trajectories and the in-plane electric field structure appear essentially similar in both models.

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Reconnection Rate for the Inhomogeneous Resistivity Petschek Model

Cited by 49 publications

References 12 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

Two-dimensional MHD model of the reconnection diffusion region

Collisionless magnetic reconnection: analytical model and PIC simulation comparison

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