Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Wyper, P. F.; Pontin, D. I.

doi:10.1063/1.4896060

Cited by 45 publications

(41 citation statements)

References 64 publications

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“…The distance between these two nulls is d 1 i ; they live for a few ion gyration timesand are accompanied by strong currents and enhanced energy conversion. A spontaneous emergence of magnetic nulls was explained in terms of topological bifurcations by Wyper & Pontin (2014a). The interconnection between the emerged radial nulls is more complex than between the spiral nulls in a flux rope.…”

Section: Results: "Multiple Nulls"mentioning

confidence: 99%

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Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

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We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind,and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their crosssections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

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Section: Results: "Multiple Nulls"mentioning

confidence: 99%

“…Observations, however, have suggested that nulls often concentrate in clusters (Deng et al 2009;Wendel & Adrian 2013). Several 3D MHD simulations addressed multiple null points (Galsgaard & Nordlund 1997;Wyper & Pontin 2014a, 2014b. Notably, the last two publications hinted atthe dominating role of the spiral nulls in the models.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

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“…For q = +  22 , the outflows form a tapered spire (Figure 12(a)) that waves and undulates (see the online movie). This wave motion follows the onset of tearing in the breakout sheet, in which blobs of high-density plasma associated with small flux ropes are formed in and ejected from the sheet (Wyper & Pontin 2014b;. Plasma in the spire is ejected at around Figure 12(b).…”

Section: Breakoutmentioning

confidence: 99%

A Breakout Model for Solar Coronal Jets with Filaments

Wyper

DeVore²,

Antiochos³

2018

ApJ

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131

162

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractRecent observations have revealed that many solar coronal jets involve the eruption of miniature versions of largescale filaments. Such "mini-filaments" are observed to form along the polarity inversion lines of strong, magnetically bipolar regions embedded in open (or distantly closing) unipolar field. During the generation of the jet, the filament becomes unstable and erupts. Recently we described a model for these mini-filament jets, in which the well-known magnetic-breakout mechanism for large-scale coronal mass ejections is extended to these smaller events. In this work we use 3D magnetohydrodynamic simulations to study in detail three realizations of the model. We show that the breakout-jet generation mechanism is robust and that different realizations of the model can explain different observational features. The results are discussed in relation to recent observations and previous jet models.

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“…At higher grid resolution, these currents should become even more filamentary in structure and greater in strength, and could produce quasi-steady heating of the loop in the aftermath of the jet. In addition, it is known that 3D null-point current layers are explosively unstable to resistive tearing at high Lundquist numbers (Wyper & Pontin 2014a, 2014b. Attaining the requisite Lundquist-number threshold demands better resolution than the simulations undertaken in this work.…”

mentioning

confidence: 80%

Simulations of Solar Jets Confined by Coronal Loops

Wyper

DeVore

2016

ApJ

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Coronal jets are collimated, dynamic events that occur over a broad range of spatial scales in the solar corona. In the open magnetic field of coronal holes, jets form quasi-radial spires that can extend far out into the heliosphere, while in closed-field regions the jet outflows are confined to the corona. We explore the application of the embedded-bipole model to jets occurring in closed coronal loops. In this model, magnetic free energy is injected slowly by footpoint motions that introduce twist within the closed dome of the jet source region, and is released rapidly by the onset of an ideal kink-like instability. Two length scales characterize the system: the width (N) of the jet source region and the footpoint separation (L) of the coronal loop that envelops the jet source. We find that both the conditions for initiation and the subsequent dynamics are highly sensitive to the ratio L/N. The longest-lasting and most energetic jets occur along long coronal loops with large L/N ratios, and share many of the features of open-field jets, while smaller L/N ratios produce shorter-duration, less energetic jets that are affected by reflections from the far-loop footpoint. We quantify the transition between these behaviors and show that our model replicates key qualitative and quantitative aspects of both quiet Sun and active-region loop jets. We also find that the reconnection between the closed dome and surrounding coronal loop is very extensive: the cumulative reconnected flux at least matches the total flux beneath the dome for small L/N, and is more than double that value for large L/N.

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Dynamic topology and flux rope evolution during non-linear tearing of 3D null point current sheets

Cited by 45 publications

References 64 publications

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Magnetic Null Points in Kinetic Simulations of Space Plasmas

A Breakout Model for Solar Coronal Jets with Filaments

Simulations of Solar Jets Confined by Coronal Loops

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