Chaos in magnetic flux ropes

Gekelman, Walter; Compernolle, B. Van; DeHaas, T.; Vincena, S.

doi:10.1088/0741-3335/56/6/064002

Cited by 34 publications

(33 citation statements)

References 55 publications

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“…Embedding delays can be implemented as a simple subsampling of data in which only L/τ values of the time series are considered [14,15] or all portions of the original time series can be used [28], a method referred to here as the length-preserving method. For example, for an embedding delay τ = 10 using the former approach, a new time series X ′ of length L ′ = 1 10 L is generated by selecting every tenth value of the original series X and the ordinal pattern probability distribution calculated for that series in the usual manner.…”

Section: Permutation Entropy and The Ch Planementioning

confidence: 99%

“…The solar wind is highly variable but there are two broad types: fast wind (V > 600 km/s) which is emitted from open coronal field lines and is typically low density (<5 protons/cm 3 ), has few large scale structures and has high amplitude but less developed turbulence, and slow wind, (V < 500 km/s) which is typically found in the ecliptic plane and originates from more complex coronal magnetic topology and is denser and more structured than the fast wind with more evolved but lower amplitude turbulence [26,27]. Here we use multiday long intervals of a fast wind stream (January [14][15][16][17][18][19][20][21]2008) and a slow wind stream (January [24][25][26][27][28][29]2010) with large scale magnetic fluctuations on the order of 10 nT.…”

Section: Introductionmentioning

confidence: 99%

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Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind

et al. 2015

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. 2015. Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind. Phys. Rev. E 91, 023101.PHYSICAL REVIEW E 91, 023101 (2015) Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind The Bandt-Pompe permutation entropy and the Jensen-Shannon statistical complexity are used to analyze fluctuating time series of three different turbulent plasmas: the magnetohydrodynamic (MHD) turbulence in the plasma wind tunnel of the Swarthmore Spheromak Experiment (SSX), drift-wave turbulence of ion saturation current fluctuations in the edge of the Large Plasma Device (LAPD), and fully developed turbulent magnetic fluctuations of the solar wind taken from the Wind spacecraft. The entropy and complexity values are presented as coordinates on the CH plane for comparison among the different plasma environments and other fluctuation models. The solar wind is found to have the highest permutation entropy and lowest statistical complexity of the three data sets analyzed. Both laboratory data sets have larger values of statistical complexity, suggesting that these systems have fewer degrees of freedom in their fluctuations, with SSX magnetic fluctuations having slightly less complexity than the LAPD edge I sat . The CH plane coordinates are compared to the shape and distribution of a spectral decomposition of the wave forms. These results suggest that fully developed turbulence (solar wind) occupies the lower-right region of the CH plane, and that other plasma systems considered to be turbulent have less permutation entropy and more statistical complexity. This paper presents use of this statistical analysis tool on solar wind plasma, as well as on an MHD turbulent experimental plasma.

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Section: Permutation Entropy and The Ch Planementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind

et al. 2015

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“…Future correlation studies will determine their morphology. Previous work has shown that the magnetic fields associated with flux rope collisions are chaotic (24). A separate C-H plane analysis of the magnetic TDS m shows they are chaotic as well.…”

Section: Discussionmentioning

confidence: 86%

“…2A, has sharp features and the 5-kHz rope oscillation is clearly visible. The case 2 flux ropes were also shown to be chaotic (24), and their corresponding pattern is shown in Fig. 3B.…”

Section: Magnetic Tds Mmentioning

confidence: 94%

Spiky electric and magnetic field structures in flux rope experiments

Gekelman

Tang

DeHaas

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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Magnetic flux ropes are structures that are common in the corona of the sun and presumably all stars. They can be thought of as the building blocks of solar structures. They have been observed in Earth's magnetotail and near Mars and Venus. When multiple flux ropes are present magnetic field line reconnection, which converts magnetic energy to other forms, can occur when they collide. The structure of multiple magnetic ropes, the interactions between multiple ropes, and their topological properties such as helicity and writhing have been studied theoretically and in laboratory experiments. Here, we report on spiky potential and magnetic fields associated with the ropes. We show that the potential structures are chaotic for a range of their temporal half-widths and the probability density function (PDF) of their widths resembles the statistical distribution of crumpled paper. The spatial structure of the magnetic spikes is revealed using a correlation counting method. Computer simulation suggests that the potential structures are the nonlinear end result of an instability involving relative drift between ions and electrons.

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“…Previous experiments have explored multiple coalescing flux ropes, 27 the first confirmation of a quasi-separatrix layer (QSL) between two flux ropes, 7 and the investigation of chaotic behavior embedded in the system. 28 The operation of the experiment is as follows: at one end of the device (Fig. 1), an oxide-coated cathode generates a background plasma (I D ¼ 4 kA, V D ¼ 42 V, He, 50% ionized).…”

Section: Methodsmentioning

confidence: 99%

Helicity transformation under the collision and merging of two magnetic flux ropes

DeHaas

Gekelman

2017

Physics of Plasmas

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Magnetic helicity has become a useful tool in the analysis of astrophysical plasmas. Its conservation in the magnetohydrodynamic limit (and other fluid approaches) constrains the global behavior of large plasma structures. One such astrophysical structure is a magnetic flux rope: a tube-like, current-carrying plasma embedded in an external magnetic field. Bundles of these ropes are commonly observed in the near-earth environment and solar atmosphere. In this well-diagnosed experiment (three-dimensional measurements of n e , T e , V p , B, J, E, and u flow), two magnetic flux ropes are generated in the Large Plasma Device at UCLA. These ropes are driven kink-unstable to trigger complex motion. As they interact, helicity conservation is examined in regions of reconnection. We examine (1) the transport of helicity and (2) the dissipation of the helicity. As the ropes move and the topology of the field lines diverge, a quasi-separatrix layer (QSL) is formed. As the QSL forms, magnetic helicity is dissipated within this region. At the same time, there is an influx of canonical helicity into the region such that the temporal derivative of magnetic helicity is zero.

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Chaos in magnetic flux ropes

Cited by 34 publications

References 55 publications

Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind

Permutation entropy and statistical complexity analysis of turbulence in laboratory plasmas and the solar wind

Spiky electric and magnetic field structures in flux rope experiments

Helicity transformation under the collision and merging of two magnetic flux ropes

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