Instability, Turbulence, and 3D Magnetic Reconnection in a Line-Tied, Zero Net Current Screw Pinch

Brookhart, Matthew; Stemo, Aaron; Zuberbier, Amanda; Zweibel, Ellen G.; Forest, C. B.

doi:10.1103/physrevlett.114.145001

Cited by 3 publications

(8 citation statements)

References 31 publications

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“…The experiment also exhibited some unexpected behaviour. In all experiments, plasmas exhibited fluctuations at much lower current levels and safety factors than expected from kink theory and previous experiments on the device (Bergerson et al 2006;Paz-Soldan et al 2011;Brookhart et al 2015). The exact physical mechanism that seed the fluctuations in these plasmas is not well understood and deserves further study.…”

Section: Resultsmentioning

confidence: 71%

“…2011; Brookhart et al. 2015). The exact physical mechanism that seed the fluctuations in these plasmas is not well understood and deserves further study.…”

Section: Resultsmentioning

confidence: 99%

“…2014; Brookhart et al. 2015). The placement of various chaotic and non-chaotic signals are shown with plasma measurement in figure 7.…”

Section: Experiments 1: the Hollow Screw Pinchmentioning

confidence: 99%

“…Recent papers have suggested that chaos and turbulence in the corona can modulate the accumulation and release of magnetic energy in line-tied coronal systems and solar flares (Rappazzo, Velli & Einaudi 2013; Brookhart et al. 2015). The behaviour of these chaotic interactions is not well understood.…”

Section: Introductionmentioning

confidence: 99%

“…Turbulence and self-organization in line-tied systems have long been important topics in space and solar physics (Russell, Priest & Lee 1990), especially in relation to the solar wind, coronal loops and solar flares. Recent papers have suggested that chaos and turbulence in the corona can modulate the accumulation and release of magnetic energy in line-tied coronal systems and solar flares (Rappazzo, Velli & Einaudi 2013;Brookhart et al 2015). The behaviour of these chaotic interactions is not well understood.…”

Section: Introductionmentioning

confidence: 99%

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Driving magnetic turbulence using flux ropes in a moderate guide field linear system

et al. 2017

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We present a series of experiments on novel, line-tied plasma geometries as a study of the generation of chaos and turbulence in line-tied systems. Plasma production and the injection scale for magnetic energy is provided by spatially discrete plasma guns that inject both plasma and current. The guns represent a technique for controlling the injection scale of magnetic energy. A two-dimensional (2-D) array of magnetic probes provides spatially resolved time histories of the magnetic fluctuations at a single cross-section of the experimental cylinder, allowing simultaneous spatial measurements of chaotic and turbulent behaviour. The first experiment shows chaotic fluctuations and self-organization in a hollow-current line-tied screw pinch. These dynamics is modulated primarily by the applied magnetic field and weakly by the plasma current and safety factor. The second experiment analyses the interactions of multiple line-tied flux ropes. The flux ropes all exhibit chaotic behaviour, and under certain conditions develop an inverse cascade to larger scales and a turbulent inertial range with magnetic energy ($E$) related to perpendicular wave number ($k_{\bot }$) as $E\propto k_{\bot }^{-2.5\pm 0.5}$.

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Section: Resultsmentioning

confidence: 71%

“…2011; Brookhart et al. 2015). The exact physical mechanism that seed the fluctuations in these plasmas is not well understood and deserves further study.…”

Section: Resultsmentioning

confidence: 99%

“…2014; Brookhart et al. 2015). The placement of various chaotic and non-chaotic signals are shown with plasma measurement in figure 7.…”

Section: Experiments 1: the Hollow Screw Pinchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Driving magnetic turbulence using flux ropes in a moderate guide field linear system

et al. 2017

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The evolution of the plasmoidal structure in the pinched column in plasma focus discharge

Kubeš

Paduch

Cikhardt

et al. 2016

Plasma Phys. Control. Fusion

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In this paper, a description is provided of the evolution of the dense spherical-like structuresplasmoids-formed in the pinched column of the dense plasma focus at the current of 1 MA at the final phase of implosion of the deuterium plasma sheath and at the phase of evolution of instabilities both at the time of HXR and neutron production. At the stratification of the plasma column, the plasma injected to the dense structures from the axially neighboring regions forms small turbulences which increase first the toroidal structures, and finally generates a nonchaotic current plasmoidal structure with central maximal density. This spontaneous evolution supports the hypothesis of the spheromak-like model of the plasmoid and its sub-millimeter analogy, high-energy spot. These spots, also called nodules formed in the filamentary structure of the current can be a source of the energy capable of accelerating the fast charged particles.

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Estimating the Rate of Field Line Braiding in the Solar Corona by Photospheric Flows

Candelaresi

Pontin

Yeates

et al. 2018

ApJ

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In this paper we seek to understand the timescale on which the photospheric motions on the Sun braid coronal magnetic field lines. This is a crucial ingredient for determining the viability of the braiding mechanism for explaining the high temperatures observed in the corona. We study the topological complexity induced in the coronal magnetic field, primarily using plasma motions extracted from magneto-convection simulations. This topological complexity is quantified using the field line winding, finite time topological entropy and passive scalar mixing. With these measures we contrast mixing efficiencies of the magneto-convection simulation, a benchmark flow known as a "blinking vortex", and finally photospheric flows inferred from sequences of observed magnetograms using local correlation tracking. While the highly resolved magneto-convection simulations induce a strong degree of field line winding and finite time topological entropy, the values obtained from the observations from the plage region are around an order of magnitude smaller. This behavior is carried over to the finite time topological entropy. Nevertheless, the results suggest that the photospheric motions induce complex tangling of the coronal field on a timescale of hours. Subject headings:

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Instability, Turbulence, and 3D Magnetic Reconnection in a Line-Tied, Zero Net Current Screw Pinch

Cited by 3 publications

References 31 publications

Driving magnetic turbulence using flux ropes in a moderate guide field linear system

Driving magnetic turbulence using flux ropes in a moderate guide field linear system

The evolution of the plasmoidal structure in the pinched column in plasma focus discharge

Estimating the Rate of Field Line Braiding in the Solar Corona by Photospheric Flows

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