Scaling of the inner electron diffusion region in collisionless magnetic reconnection

Divin, Andrey; Lapenta, Giovanni; Semenov, V. S.; Еркаев, Н. В.; Korovinskiy, Daniil; Biernat, H. K.

doi:10.1029/2011ja017464

Cited by 23 publications

(31 citation statements)

References 44 publications

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“…(5) U ez . This expression is consistent with past theories of E y component produced by the non-gyrotropic effects near the X-point (E NG y ) (e.g., Kuznetsova et al, 1998;Hesse et al, 1999;Dorfman et al, 2008;Divin et al, 2012), in which they derived…”

Section: Spatial Dimension Of the Electron Diffusion Region In The Z supporting

confidence: 78%

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Spatial dimensions of the electron diffusion region in anti-parallel magnetic reconnection

Nakamura

Haseagwa

2016

Ann. Geophys.

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Abstract. Spatial dimensions of the detailed structures of the electron diffusion region in anti-parallel magnetic reconnection were analyzed based on two-dimensional fully kinetic particle-in-cell simulations. The electron diffusion region in this study is defined as the region where the positive reconnection electric field is sustained by the electron inertial and non-gyrotropic pressure components. Past kinetic studies demonstrated that the dimensions of the whole electron diffusion region and the inner non-gyrotropic region are scaled by the electron inertial length d e and the width of the electron meandering motion, respectively. In this study, we successfully obtained more precise scalings of the dimensions of these two regions than the previous studies by performing simulations with sufficiently small grid spacing (1/16-1/8 d e ) and a sufficient number of particles (800 particles cell −1 on average) under different conditions changing the ion-to-electron mass ratio, the background density and the electron β e (temperature). The obtained scalings are adequately supported by some theories considering spatial variations of field and plasma parameters within the diffusion region. In the reconnection inflow direction, the dimensions of both regions are proportional to d e based on the background density. Both dimensions also depend on β e based on the background values, but the dependence in the inner region (∼ 0.375th power) is larger than the whole region (0.125th power) reflecting the orbits of meandering and accelerated electrons within the inner region. In the outflow direction, almost only the non-gyrotropic component sustains the positive reconnection electric field. The dimension of this single-scale diffusion region is proportional to the ionelectron hybrid inertial length (d i d e ) 1/2 based on the background density and weakly depends on the background β e with the 0.25th power. These firm scalings allow us to predict observable dimensions in real space which are indeed in reasonable agreement with past in situ spacecraft observations in the Earth's magnetotail and have important implications for future observations with higher resolutions such as the NASA Magnetospheric Multiscale (MMS) mission.

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Section: Spatial Dimension Of the Electron Diffusion Region In The Z supporting

confidence: 78%

“…Similar scalings were also seen in past kinetic simulations (Hesse et al, 1999;Ricci et al, 2002;Daughton et al, 2006;Karimabadi et al, 2007;Divin et al, 2012), where they indicated that the dimension of the electron diffusion region in the x direction is proportional to (m e /m i )…”

Section: Spatial Dimensions In the X Directionsupporting

confidence: 61%

Spatial dimensions of the electron diffusion region in anti-parallel magnetic reconnection

Nakamura

Haseagwa

2016

Ann. Geophys.

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“…It is important to note that Divin et al, 21 in a related analysis of a mass ratio 1836 PIC reconnection simulation, have found a ¼ 0:36 (their parameter k a). It is not clear whether the difference between this value and the cluster of values in Table I represents mass ratio dependence or not.…”

Section: Discussionmentioning

confidence: 97%

New expression for collisionless magnetic reconnection rate

Klimas

2015

Physics of Plasmas

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For 2D, symmetric, anti-parallel, collisionless magnetic reconnection, new expressions for the reconnection rate in the electron diffusion region are introduced. It is shown that these expressions can be derived in just a few simple steps from a physically intuitive starting point; the derivations are given in their entirety, and the validity of each step is confirmed. The predictions of these expressions are compared to the results of several long-duration, open-boundary particle-in-cell reconnection simulations to demonstrate excellent agreement. V C 2015 AIP Publishing LLC.

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“…Numerical simulations showed that the X-line region can contain several scales corresponding to different intensities of the current density carried by various particle populations (see, e.g., Hesse et al, 2006;Karimabadi et al, 2007;Divin et al, 2010, and references therein). For example, accelerated electrons can carry strong current, which provides a decrease of the scale L z in the vicinity of the X-line (Divin et al, 2012). However, here we assume that population of accelerated electrons is sufficiently small in comparison with the thermal background population.…”

Section: Model Of Electron Acceleration In X-linementioning

confidence: 99%

“…Corresponding components of the electric field are E z ∼ −z, E x ∼ x (see, e.g., analytical model by Korovinskiy et al, 2008). The amplitude of the scalar potential ϕ is defined by the pressure balance and can reach ∼ B 2 0 /4πn 0 e ∼ 1-10 keV, where n 0 is the plasma density in the X-line (Divin et al, 2012).…”

Section: Model Of Electron Acceleration In X-linementioning

confidence: 99%

Double power-law spectra of energetic electrons in the Earth magnetotail

et al. 2013

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Abstract. In this paper, we consider electron acceleration in the vicinity of X-line and corresponding formation of energy spectra. We develop an analytical model including the effect of the electron trapping by electrostatic fields and surfing acceleration. Speiser, Fermi and betatron mechanisms of acceleration are also taken into account. Analytical estimates are verified by the numerical integration of electron trajectories. The surfing mechanism and adiabatic heating are responsible for the formation of the double power-law spectrum in agreement with the previous studies. The energy of the spectrum knee is about ∼150 keV for typical conditions of the Earth magnetotail. We compare theoretical results with the spacecraft observations of electron double power-law spectra in the magnetotail and demonstrate that the theory is able to describe typical energy of the spectra knee. We also estimate the role of relativistic effects and magnetic field fluctuations on the electron acceleration: the acceleration is more stable for relativistic electrons, while fluctuations of the magnetic field cannot significantly decrease the gained energy for typical magnetospheric conditions.

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Scaling of the inner electron diffusion region in collisionless magnetic reconnection

Cited by 23 publications

References 44 publications

Spatial dimensions of the electron diffusion region in anti-parallel magnetic reconnection

Spatial dimensions of the electron diffusion region in anti-parallel magnetic reconnection

New expression for collisionless magnetic reconnection rate

Double power-law spectra of energetic electrons in the Earth magnetotail

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