Three‐dimensional collisionless magnetic reconnection in the presence of a guide field

Pritchett, P. L.; Coroniti, F. V.

doi:10.1029/2003ja009999

Cited by 283 publications

(296 citation statements)

References 56 publications

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“…9) and in simulations (e.g. Hoshino et al, 2001;Pritchett and Coroniti, 2004) that are consistent with the Hall current system. The event studied in this work occurred relatively far away from the X-line, the shear angle was about 114 • and it was associated with a relatively large guide magnetic field.…”

Section: Discussion and Summarymentioning

confidence: 98%

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Wind observations of low energy particles within a solar wind reconnection region

2008

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Abstract. We report characteristics of thermal particle observations during the encounter of the Wind satellite with the separatrix and the outflow domains of a reconnection event on 22 July 1999 in the solar wind. During the studied event the electrostatic analyzers on Wind were transmitting threedimensional electron and proton distributions in a burst mode every 3 s, the spin period of the spacecraft. The event was associated with a magnetic shear angle of 114 • and a large guide magnetic field. The observations suggest that Wind crossed the separatrix and outflow regions about a thousand of ion skin depths from the X-line. At the leading separator boundary, a strong proton beam was identified that originated from the direction of the X-line. In the separatrix and the outflow regions, the phase space distributions of thermal electrons displayed field aligned bidirectional anisotropy. During the crossings of the current sheets bounding the outflow region, we identified two adjacent layers in which the dominant thermal electron flows were towards the X-line at the inner edges of the current sheets and away from the X-line at the outer edges. Interestingly, simulation studies and observations in the Earth's magnetosphere have revealed that the electron flows are reversed, consistent with the Hall current system.

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Section: Discussion and Summarymentioning

confidence: 98%

“…However, neither large out-of-plane magnetic field or component reconnection have been shown to produce such a features (e.g. Rogers and Denton, 2003;Pritchett and Coroniti, 2004). 2-D Hall MHD simulation conducted by Scholer and Lottermoser (1998) resulted in slow mode switch-off shocks bounding the reconnection outflow region.…”

Section: Discussion and Summarymentioning

confidence: 99%

Wind observations of low energy particles within a solar wind reconnection region

2008

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“…As mentioned above, however, the reconnection rate will gradually diminish with the enhancement of the guide field. That is to say, the reconnection electric field weakens as the guide field increases [40]. Even with the presence of a guide field, the magnetic field strength inside the reconnection plane is still very low so that the reconnection electric field within the electron diffusion region is mainly produced by the electron pressure gradient term.…”

Section: Characteristics Of the Reconnection Diffusion Regionmentioning

confidence: 98%

“…While the guide field is strong enough and comparable to the magnitude to the magnetic field out of the current sheet, the reconnection rate drops significantly [25,40]. Electrons stream into the Xpoint along one pair of separatrices, whereas along the other pair of separatrices, electrons stream out of the X-point.…”

Section: Characteristics Of the Reconnection Diffusion Regionmentioning

confidence: 99%

Electron dynamics in collisionless magnetic reconnection

Wang

Xie

et al. 2011

Chin. Sci. Bull.

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Magnetic reconnection provides a physical mechanism for fast energy conversion from magnetic energy to plasma kinetic energy. It is closely associated with many explosive phenomena in space plasma, usually collisionless in character. For this reason, researchers have become more interested in collisionless magnetic reconnection. In this paper, the various roles of electron dynamics in collisionless magnetic reconnection are reviewed. First, at the ion inertial length scale, ions and electrons are decoupled. The resulting Hall effect determines the reconnection electric field. Moreover, electron motions determine the current system inside the reconnection plane and the electron density cavity along the separatrices. The current system in this plane produces an out-of-plane magnetic field. Second, at the electron inertial length scale, the anisotropy of electron pressure determines the magnitude of the reconnection electric field in this region. The production of energetic electrons, which is an important characteristic during magnetic reconnection, is accelerated by the reconnection electric field. In addition, the different topologies, temporal evolution and spatial distribution of the magnetic field affect the accelerating process of electrons and determine the final energy of the accelerated electrons. Third, we discuss results from simulations and spacecraft observations on the secondary magnetic islands produced due to secondary instabilities around the X point, and the associated energetic electrons. Furthermore, progress in laboratory plasma studies is also discussed in regard to electron dynamics during magnetic reconnection. Finally, some unresolved problems are presented. Magnetic reconnection provides an effective mechanism for fast conversion of magnetic energy into plasma kinetic energy. Simultaneously, the topology of magnetic field changes [1][2][3]. First proposed by Giovanelli, magnetic reconnection is related to many explosive phenomena, such as solar flares, magnetospheric substorms, and disruptive instabilities in Tokamak plasmas [4][5][6][7][8]. Giovanelli thought discharge phenomena would occur around the neutral line or point where the magnetic field vanishes, an idea that could be very important in solar-flare production [9]. In 1958, Dungey first introduced the concept of "magnetic reconnection" , applying it in the construction of the open *Corresponding author (email: qmlu@ustc.edu.cn) Earth magnetosphere model [10]. The first magnetic reconnection model was proposed by Sweet and Parker, separately. In this model, plasma and magnetic field flow into the center of the current sheet from both sides where magnetic field lines are cut off and reconnected. Magnetic energy is converted into plasma kinetic energy; energized plasma then flows out of the region from both ends [11,12]. However, the predicted reconnection rate in this model is so low that it is unable to account for the explosive phenomena in space. Petschek improved the Sweet-Parker model and suggested that magnetic reconnecti...

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“…Energetic electron beams are ubiquitous throughout the solar system, such as the upstream from the interplanetary shock [1][2][3] , the auroral ionosphere 4,5 , solar flares 6 , in the outflow region of magnetic reconnection 7,8 and possibly the Earth's outer radiation belt 9 .…”

Section: Introductionmentioning

confidence: 99%

Electrostatic and whistler instabilities excited by an electron beam

Bortnik

Compernolle

et al. 2017

Physics of Plasmas

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The electron beam-plasma system is ubiquitous in the space plasma environment.Here, using a Darwin particle-in-cell method, the excitation of electrostatic and whistler instabilities by a gyrating electron beam is studied in support of recent laboratory experiments. It is assumed that the total plasma frequency ω pe is larger than the electron cyclotron frequency Ω e . The fast-growing electrostatic beam-mode waves saturate in a few plasma oscillations by slowing down and relaxing the electron beam parallel to the background magnetic field. Upon their saturation, the finite amplitude electrostatic beam-mode waves can resonate with the tail of the background thermal electrons and accelerate them to the beam parallel velocity. The slowergrowing whistler waves are excited in primarily two resonance modes: (a) through Landau resonance due to the inverted slope of the beam electrons in the parallel velocity; (b) through cyclotron resonance by scattering electrons to both lower pitch angles and smaller energies. It is demonstrated that, for a field-aligned beam, the whistler instability can be suppressed by the electrostatic instability due to a faster energy transfer rate between beam electrons and the electrostatic waves. Such a competition of growth between whistler and electrostatic waves depends on the ratio of ω pe /Ω e . In terms of wave propagation, beam-generated electrostatic waves are confined to the beam region whereas beam-generated whistler waves transport energy away from the beam. a) xinan@atmos.ucla.edu 1 arXiv:1707.05346v1 [physics.plasm-ph]

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Three‐dimensional collisionless magnetic reconnection in the presence of a guide field

Cited by 283 publications

References 56 publications

Wind observations of low energy particles within a solar wind reconnection region

Wind observations of low energy particles within a solar wind reconnection region

Electron dynamics in collisionless magnetic reconnection

Electrostatic and whistler instabilities excited by an electron beam

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