Dynamic magnetic reconnection at an X-type neutral point

Craig, I. J. D.; McClymont, A. N.

doi:10.1086/185997

Cited by 117 publications

(216 citation statements)

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“…A resistive X-point in the flaring region may go to a damped oscillatory regime of the reconnection, in which the angle between the X-point field lines, where a flare maximizes, may change periodically. Therefore, these waves are found to be the fast waves of which the period is determined by the Alfvén speed profile around the X-point forming the resonator, generating the multiperiodic QPP around the peak of the flare (Craig & McClymont 1991). This is similar to the work by Takasao & Shibata (2016), who showed QPPs could be spontaneously excited by above-the-loop-top oscillations controlled by the back-flow of the reconnection outflow.…”

Section: T H E O R E T I C a L I N T E R P R E Tat I O Nsupporting

confidence: 77%

Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

Doyle

Shetye

Antonova

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Section: T H E O R E T I C a L I N T E R P R E Tat I O Nsupporting

confidence: 77%

Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

Doyle

Shetye

Antonova

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…They show that the propagation of the m = 0 wave towards the null point generates an exponentially large increase in the current density and that magnetic resistivity dissipates this current in a time related to log η. Craig & McClymont (1991, 1993 investigate the normal mode solutions for both m = 0 and m 0 modes with resistivity included. Again, they emphasise that the current builds up as the inverse square of the radial distance from the null point.…”

Section: Introductionmentioning

confidence: 99%

MHD mode coupling in the neighbourhood of a 2D null point

McLaughlin¹,

Hood²

2006

A&A

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Context. At this time there does not exist a robust set of rules connecting low and high β waves across the β ≈ 1 layer. The work here contributes specifically to what happens when a low β fast wave crosses the β ≈ 1 layer and transforms into high β fast and slow waves. Aims. The nature of fast and slow magnetoacoustic waves is investigated in a finite β plasma in the neighbourhood of a twodimensional null point. Methods. The linearised equations are solved in both polar and cartesian forms with a two-step Lax-Wendroff numerical scheme. Analytical work (e.g. small β expansion and WKB approximation) also complement the work. Results. It is found that when a finite gas pressure is included in magnetic equilibrium containing an X-type null point, a fast wave is attracted towards the null by a refraction effect and that a slow wave is generated as the wave crosses the β ≈ 1 layer. Current accumulation occurs close to the null and along nearby separatrices. The fast wave can now pass through the origin due to the non-zero sound speed, an effect not previously seen in related papers but clear seen for larger values of β. Some of the energy can now leave the region of the null point and there is again generation of a slow wave component (we find that the fraction of the incident wave converted to a slow wave is proportional to β). We conclude that there are two competing phenomena; the refraction effect (due to the variable Alfvén speed) and the contribution from the non-zero sound speed. Conclusions. These experiments illustrate the importance of the magnetic topology and of the location of the β ≈ 1 layer in the system.

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“…The conventional picture of planar reconnection involves the advection of material across identical separatrix planes, the field lines being cut and rejoined at the center of the X-point. Analytic models of this process are provided by linear X-point theory (Craig & McCly mont 1991, 1993Hassam 1992). It is suspected, however, that more complicated flow topologies are required in the presence of three-dimensional neutral points (e.g., Rosenau 1979).…”

Section: Introductionmentioning

confidence: 99%

Exact Solutions for Steady State, Spine, and Fan Magnetic Reconnection

Craig¹,

Fabling²

1996

ApJ

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The problem of steady state, incompressible magnetic reconnection in three dimensions is addressed. It is shown that exact reconnection solutions can be constructed by superposing nonlinear disturbances onto three-dimensional magnetic X-points. There are two distinct families of reconnection solutions. These can be understood in terms of the eigenstructure of the null, that is, in terms of the " spine" curves and "fan" surfaces that define the separatrices of the field. One family of solutions is driven by dis turbances in the fan and involves quasi-cylindrical current structures aligned to the axis of the spine; the other is associated with advection across the spine and a global current sheet aligned to the fan. Although both spine and fan solutions reduce to the two-dimensional analytic, shear-flow solutions of Craig & Henton, the three-dimensional spine current formulation allows far richer reconnective current structures.

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Dynamic magnetic reconnection at an X-type neutral point

Cited by 117 publications

References 0 publications

Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

MHD mode coupling in the neighbourhood of a 2D null point

Exact Solutions for Steady State, Spine, and Fan Magnetic Reconnection

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