The impact of small-scale turbulence on laminar magnetic reconnection

Watson, P.G.; Oughton, Sean; Craig, I. J. D.

doi:10.1063/1.2458595

Cited by 15 publications

(11 citation statements)

References 36 publications

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“…An enhancement of the reconnection rate was reported in their numerical study, but the setup precluded the calculation of a long-term average reconnection rate. A more recent study along the lines of the approach in Matthaeus & Lamkin (1985) is that of Watson et al (2007), where the effects of small-scale turbulence on 2D reconnection were studied and no significant effects of turbulence on reconnection were found. However, this new work studies flow-driven merging in the super-Alfvénic limit, with very strong flows ramming magnetic field together.…”

Section: Alternative Ideas On the Role Of Turbulence In Magnetic Recomentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

183

260

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Magnetic field lines in astrophysical plasmas are expected to be frozen-in at scales larger than the ion gyroradius. The rapid reconnection of magnetic-flux structures with dimensions vastly larger than the gyroradius requires a breakdown in the standard Alfvén flux-freezing law. We attribute this breakdown to ubiquitous MHD plasma turbulence with power-law scaling ranges of velocity and magnetic energy spectra. Lagrangian particle trajectories in such environments become "spontaneously stochastic," so that infinitely many magnetic field lines are advected to each point and must be averaged to obtain the resultant magnetic field. The relative distance between initial magnetic field lines which arrive at the same final point depends upon the properties of two-particle turbulent dispersion. We develop predictions based on the phenomenological Goldreich & Sridhar theory of strong MHD turbulence and on weak MHD turbulence theory. We recover the predictions of the Lazarian & Vishniac theory for the reconnection rate of large-scale magnetic structures. Lazarian & Vishniac also invoked "spontaneous stochasticity," but of the field lines rather than of the Lagrangian trajectories. More recent theories of fast magnetic reconnection appeal to microscopic plasma processes that lead to additional terms in the generalized Ohm's law, such as the collisionless Hall term. We estimate quantitatively the effect of such processes on the inertial-range turbulence dynamics and find them to be negligible in most astrophysical environments. For example, the predictions of the Lazarian & Vishniac theory are unchanged in Hall MHD turbulence with an extended inertial range, whenever the ion skin depth δ i is much smaller than the turbulent integral length or injection-scale L i .

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Section: Alternative Ideas On the Role Of Turbulence In Magnetic Recomentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

183

260

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“…For instance, in a more recent study along the lines of the approach in Matthaeus and Lamkin (1985), i.e. in Watson et al (2007), the effects of small-scale turbulence on 2D reconnection were studied and no significant effects of turbulence on reconnection was reported. Servidio et al (2010) have more recently made a study of Ohmic electric fields at X-points in homogeneous, decaying 2D MHD turbulence.…”

Section: Turbulent Reconnection: 3d Versus 2dmentioning

confidence: 99%

Theory and Applications of Non-relativistic and Relativistic Turbulent Reconnection

Lazarian¹,

Kowal

Takamoto

et al. 2016

Magnetic Reconnection

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Realistic astrophysical environments are turbulent due to the extremely high Reynolds numbers of the flows. Therefore, the theories of reconnection intended for describing astrophysical reconnection should not ignore the effects of turbulence on magnetic reconnection. Turbulence is known to change the nature of many physical processes dramatically and in this review we claim that magnetic reconnection is not an exception. We stress that not only astrophysical turbulence is ubiquitous, but also magnetic reconnection itself induces turbulence. Thus turbulence must be accounted for in any realistic astrophysical reconnection setup. We argue that due to the similarities of MHD turbulence in relativistic and non-relativistic cases the theory of magnetic reconnection developed for the non-relativistic case can be extended to the relativistic case and we provide numerical simulations that support this conjecture. We also provide quantitative comparisons of the theoretical predictions and results of numerical experiments, including the situations when turbulent reconnection is self-driven, i.e. the turbulence

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“…An enhancement of the reconnection rate was reported, but the numerical setup precluded the calculation of a long term average reconnection rate. A more recent study along the approach in Matthaeus and Lamkin (1985) is one in Watson et al (2007), where the effects of small scale turbulence on 2D reconnection were studied and no significant effects of turbulence on reconnection were reported for the setup chosen by the authors. Later, Servidio et al (2010) redone the modeling of 2D turbulent reconnection following Matthaeus and Lamkin (1985) with much higher resolutions.…”

Section: Limitations Of 2d Reconnectionmentioning

confidence: 99%

Reconnection studies under different types of turbulence driving

Kowal¹,

Lazarían²,

Vishniac

et al. 2012

Nonlin. Processes Geophys.

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Abstract. We study a model of fast magnetic reconnection in the presence of weak turbulence proposed by Lazarian and Vishniac (1999) using three-dimensional direct numerical simulations. The model has been already successfully tested in Kowal et al. (2009) confirming the dependencies of the reconnection speed V rec on the turbulence injection power P inj and the injection scale l inj expressed by a constraintinj and no observed dependency on Ohmic resistivity. In Kowal et al. (2009), in order to drive turbulence, we injected velocity fluctuations in Fourier space with frequencies concentrated around k inj = 1/ l inj , as described in Alvelius (1999). In this paper, we extend our previous studies by comparing fast magnetic reconnection under different mechanisms of turbulence injection by introducing a new way of turbulence driving. The new method injects velocity or magnetic eddies with a specified amplitude and scale in random locations directly in real space. We provide exact relations between the eddy parameters and turbulent power and injection scale. We performed simulations with new forcing in order to study turbulent power and injection scale dependencies. The results show no discrepancy between models with two different methods of turbulence driving exposing the same scalings in both cases. This is in agreement with the Lazarian and Vishniac (1999) predictions. In addition, we performed a series of models with varying viscosity ν. Although Lazarian and Vishniac (1999) do not provide any prediction for this dependence, we report a weak relation between the reconnection speed with viscosity, V rec ∼ ν −1/4 .

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The impact of small-scale turbulence on laminar magnetic reconnection

Cited by 15 publications

References 36 publications

Fast Magnetic Reconnection and Spontaneous Stochasticity

Fast Magnetic Reconnection and Spontaneous Stochasticity

Theory and Applications of Non-relativistic and Relativistic Turbulent Reconnection

Reconnection studies under different types of turbulence driving

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