A New Paradigm for 3D Collisionless Magnetic Reconnection

Lapenta, Giovanni

doi:10.1007/978-94-007-1069-6_18

Cited by 5 publications

(5 citation statements)

References 17 publications

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“…Observations have also revealed flapping oscillations during the growth phase of a substorm [ Runov et al , 2009]. Indeed, other theoretical works attempted to relate reconnection onset to the plasma sheet oblique kink mode [ Galeev and Zelenyi , 1976; Zhu and Winglee , 1996; Pritchett et al , 1996; Lapenta and Brackbill , 2000; Wiegelmann and Büchner , 2000; Lapenta , 2003; Fujimoto , 2011]. Reconnection due to the oblique kink mode can be expected as close to the Earthward edge of the plasma sheet as reconnection due to ballooning interchange.…”

Section: Summary and Discussionmentioning

confidence: 99%

Kinetic ballooning/interchange instability in a bent plasma sheet

Panov¹,

Nakamura²,

Baumjohann³

et al. 2012

J. Geophys. Res.

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[1] We use Time History of Events and Macroscale Interactions during Substorms (THEMIS) and GOES observations to investigate the plasma sheet evolution on 28 February 2008 between 6:50 and 7:50 UT, when there developed strong magnetic field oscillations with periods of 100 s. Using multispacecraft analysis of the plasma sheet observations and an empirical plasma sheet model, we determine both the large-scale evolution of the plasma sheet and the properties of the oscillations. We found that the oscillations exhibited signatures of kinetic ballooning/interchange instability fingers that developed in a bent current sheet. The interchange oscillations had a sausage structure, propagated duskward at a velocity of about 100 km/s, and were associated with fast radial electron flows. We suggest that the observed negative gradient of the Z GSM magnetic field component (∂B Z /∂X) was a free energy source for the kinetic ballooning/interchange instability. Tens of minutes later a fast elongation of ballooning/interchange fingers was detected between 6 and 16 R E downtail with the length-to-width ratio exceeding 20. The finger elongation ended with signatures of reconnection in an embedded current sheet near the bending point. These observations suggest a complex interplay between the midtail and near-Earth plasma sheet dynamics, involving localized fluctuations in both cross-tail and radial directions before current sheet reconnection.

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Section: Summary and Discussionmentioning

confidence: 99%

Kinetic ballooning/interchange instability in a bent plasma sheet

Panov¹,

Nakamura²,

Baumjohann³

et al. 2012

J. Geophys. Res.

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“…First, there are current sheet instabilities in the plane outside of the tearing plane. Examples include ion/ion kink instability [e.g., Karimabadi et al , 2003, and references therein] and lower‐hybrid drift instability (LHDI) [e.g., Buchner and Kuska , 1999; Lapenta et al, , 2003; Lapenta , 2003; Scholer et al , 2003; Daughton et al , 2004; Ricci et al , 2004]. Of the various current instabilities, LHDI is perhaps the most likely to affect the tearing mode [ Karimabadi et al , 2004b].…”

Section: Application To Magnetopausementioning

confidence: 99%

Antiparallel versus component merging at the magnetopause: Current bifurcation and intermittent reconnection

Karimabadi

2005

J. Geophys. Res.

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[1] One of the major unresolved issues regarding magnetic reconnection at the dayside magnetopause is the location where reconnection first occurs during periods of a large interplanetary magnetic field B y . In order to address this issue, we examine and contrast the onset of reconnection in the presence and absence of a finite guide field (B y ). In an accompanying paper we showed that in case of one linearly unstable mode, tearing saturates at amplitudes too small to be of relevance to transport at the magnetopause, even in the antiparallel case. However, we show that in general a number of modes are simultaneously unstable at the magnetopause. This process is aided by the presence of electron temperature anisotropy which broadens the unstable spectrum, extending it to very short wavelengths. Multimode tearing gets past the single mode stabilization and grows to large amplitudes in several stages: the initial linear stage, the coalescence process which proceeds at a slower growth rate, the growth and dominance of the longest wavelength in the system, and a final explosive phase which leads to a saturated state with a bifurcated current sheet. The aspect ratio of the magnetic island at the end of the explosive phase is $0.2. This is in good agreement with the aspect ratio of the magnetic island structure at Earth's magnetopause reconstructed from the single-spacecraft data by Hau and Sonnerup (1999). We find that in addition to coalescence, there can occur stretching of the X lines. This leads to a recurrent reconnection process where only a single, rather than a pair of magnetic structures are periodically produced, reminiscent of flux transfer events. Although the detailed properties of the various interacting modes are altered in the presence of a guide field, the basic scenario including the final explosive phase of the system remains even for very large guide fields. We calculate the steady state reconnection rate as a function of guide field and plasma beta and show that fast reconnection is obtained even for modest values of guide field. Detailed application of these results to the magnetopause is discussed. One key finding is that it takes a very weak guide field of less than 0.07 of the magnetosheath field to transition away from the antiparallel reconnection. The linear growth rate of isotropic tearing compared to convection time is fast only for thin sheets. In the absence of electron temperature anisotropies, both antiparallel and component merging remain competitive as long as the guide field is not too strong ( 0.4). Local condition, most importantly the shear flow, is identified as one effect that may change the behavior of reconnection in the antiparallel versus component merging.

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“…Moreover, using simulations, we self-consistently explore nonlinear problems which lie beyond analytical theory. Simulations expand our knowledge regarding magnetic reconnection processes in two dimensions (Birn et al 2001;Shay et al 2001;Loureiro et al 2009;Servidio et al 2009Servidio et al , 2010Bessho et al 2017) and in three dimensions Pritchett & Coroniti 2001;Lapenta 2003;Lapenta et al 2006;Kowal et al 2009;Daughton et al 2011;Baumann, Galsgaard & Nordlund 2013;Liu et al 2013;Pritchett 2013;Muñoz & Büchner 2018). The use of high-performance computing facilities and increasing computational capabilities facilitate the study of plasmas from first principles using particle-in-cell (PIC) simulations (Lapenta 2012;Germaschewski et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional magnetic reconnection in particle-in-cell simulations of anisotropic plasma turbulence

et al. 2021

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We use three-dimensional (3-D) fully kinetic particle-in-cell simulations to study the occurrence of magnetic reconnection in a simulation of decaying turbulence created by anisotropic counter-propagating low-frequency Alfvén waves consistent with critical-balance theory. We observe the formation of small-scale current-density structures such as current filaments and current sheets as well as the formation of magnetic flux ropes as part of the turbulent cascade. The large magnetic structures present in the simulation domain retain the initial anisotropy while the small-scale structures produced by the turbulent cascade are less anisotropic. To quantify the occurrence of reconnection in our simulation domain, we develop a new set of indicators based on intensity thresholds to identify reconnection events in which both ions and electrons are heated and accelerated in 3-D particle-in-cell simulations. According to the application of these indicators, we identify the occurrence of reconnection events in the simulation domain and analyse one of these events in detail. The event is related to the reconnection of two flux ropes, and the associated ion and electron exhausts exhibit a complex 3-D structure. We study the profiles of plasma and magnetic-field fluctuations recorded along artificial-spacecraft trajectories passing near and through the reconnection region. Our results suggest the presence of particle heating and acceleration related to small-scale reconnection events within magnetic flux ropes produced by the anisotropic Alfvénic turbulent cascade in the solar wind. These events are related to current structures of the order of a few ion inertial lengths in size.

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A New Paradigm for 3D Collisionless Magnetic Reconnection

Cited by 5 publications

References 17 publications

Kinetic ballooning/interchange instability in a bent plasma sheet

Kinetic ballooning/interchange instability in a bent plasma sheet

Antiparallel versus component merging at the magnetopause: Current bifurcation and intermittent reconnection

Three-dimensional magnetic reconnection in particle-in-cell simulations of anisotropic plasma turbulence

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