Observation of a Helical Self-Organized State in a Compact Toroidal Plasma

Cothran, C. D.; Brown, M. R.; Gray, T.; Schaffer, M. J.; Marklin, G.J.

doi:10.1103/physrevlett.103.215002

Cited by 26 publications

(56 citation statements)

References 17 publications

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“…(1) and (2) uniquely, we have to specify boundary conditions for velocity and magnetic field. At an impermeable surface the normal component of velocity vanishes, v r r¼1 ¼ 0; (5) and the normal component of magnetic field and the tangential component of electric field are zero at the perfectly conducting boundary, which is equivalent to…”

Section: Statement Of the Problemmentioning

confidence: 99%

“…Mathematically the relaxation theory is formulated as a variational procedure for obtaining a relaxed state by minimizing the energy subject to constraints. The Taylor theory has been successfully tested in experiments [4][5][6] and applied for explaining the magnetic structures in laboratory plasmas such as the reversed-field pinch (RFP), multipinch, and spheromak. 2,3 However, the classical Taylor theory does not include possibility of flows that are ubiquitous in experimentally observed relaxed states.…”

Section: Introductionmentioning

confidence: 99%

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Minimum energy states of the cylindrical plasma pinch in single-fluid and Hall magnetohydrodynamics

et al. 2012

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Relaxed states of a plasma column are found analytically in single-fluid and Hall magnetohydrodynamics (MHD). We perform complete minimization of the energy with constraints imposed by invariants inherent in the corresponding models. It is shown that the relaxed state in Hall MHD is a force-free magnetic field with uniform axial flow and/or rigid azimuthal rotation. In contrast, the relaxed states in single-fluid MHD are more complex due to the coupling between velocity and magnetic field. Cylindrically and helically symmetric relaxed states are considered for both models. Helical states may be time dependent and analogous to helical waves, propagating on a cylindrically symmetric background. Application of our results to reversed-field pinches (RFP) is discussed. The radial profile of the parallel momentum predicted by the single-fluid MHD relaxation theory is shown to be in reasonable agreement with experimental observation from the Madison symmetric torus RFP experiment.

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Section: Statement Of the Problemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Minimum energy states of the cylindrical plasma pinch in single-fluid and Hall magnetohydrodynamics

et al. 2012

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“…An observation of relaxation to a nonaxisymmetric plasma state has previously been made in the SSX device, albeit with the much smaller aspect ratio of L/a = 3.0. [12] The λa for the minimum energy state for the wind tunnel flux conserver was calculated using a method similar to the one outlined in Finn et al [7], modified to utilize singular value decomposition. This resulted in λa = 3.136, which is within 1% of the λa value of 3.11 for the infinite cylinder state.…”

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confidence: 99%

Observation of a Relaxed Plasma State in a Quasi-Infinite Cylinder

2013

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“…Additional solar-relevant experiments are possible by making use of the properties of helical Taylor relaxed states [47]. These states roughly resemble a closed loop of flux that has been squeezed to fit inside a long cylindrical conducting boundary, then twisted with a pitch that asymptotically reaches a helical wave number of kR = 1.23 for very elongated cylinders, where k is the wavenumber and R is the radius; see Figure 13b.…”

Section: Nrl Space Physics Simulation Chambermentioning

confidence: 99%

Exploiting Laboratory and Heliophysics Plasma Synergies

et al. 2010

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Recent advances in space-based heliospheric observations, laboratory experimentation, and plasma simulation codes are creating an exciting new cross-disciplinary opportunity for understanding fast energy release and transport mechanisms in heliophysics and laboratory plasma dynamics, which had not been previously accessible. This article provides an overview of some new observational, experimental, and computational assets, and discusses current and near-term activities towards exploitation of synergies involving those assets. This overview does not claim to be comprehensive, but instead covers mainly activities closely associated with the authors' interests and reearch. Heliospheric observations reviewed include the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the National Aeronautics and Space Administration (NASA) Solar Terrestrial Relations Observatory (STEREO) mission, the first instrument to provide remote sensing imagery observations with spatial continuity extending from the Sun to the Earth, and the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Japanese Hinode spacecraft that is measuring spectroscopically OPEN ACCESSEnergies 2010, 3 1015 physical parameters of the solar atmosphere towards obtaining plasma temperatures, densities, and mass motions. The Solar Dynamics Observatory (SDO) and the upcoming Solar Orbiter with the Heliospheric Imager (SoloHI) on-board will also be discussed. Laboratory plasma experiments surveyed include the line-tied magnetic reconnection experiments at University of Wisconsin (relevant to coronal heating magnetic flux tube observations and simulations), and a dynamo facility under construction there; the Space Plasma Simulation Chamber at the Naval Research Laboratory that currently produces plasmas scalable to ionospheric and magnetospheric conditions and in the future also will be suited to study the physics of the solar corona; the Versatile Toroidal Facility at the Massachusetts Institute of Technology that provides direct experimental observation of reconnection dynamics; and the Swarthmore Spheromak Experiment, which provides well-diagnosed data on three-dimensional (3D) null-point magnetic reconnection that is also applicable to solar active regions embedded in pre-existing coronal fields. New computer capabilities highlighted include: HYPERION, a fully compressible 3D magnetohydrodynamics (MHD) code with radiation transport and thermal conduction; ORBIT-RF, a 4D Monte-Carlo code for the study of wave interactions with fast ions embedded in background MHD plasmas; the 3D implicit multi-fluid MHD spectral element code, HiFi; and, the 3D Hall MHD code VooDoo. Research synergies for these new tools are primarily in the areas of magnetic reconnection, plasma charged particle acceleration, plasma wave propagation and turbulence in a diverging magnetic field, plasma atomic processes, and magnetic dynamo behavior.

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Observation of a Helical Self-Organized State in a Compact Toroidal Plasma

Cited by 26 publications

References 17 publications

Minimum energy states of the cylindrical plasma pinch in single-fluid and Hall magnetohydrodynamics

Minimum energy states of the cylindrical plasma pinch in single-fluid and Hall magnetohydrodynamics

Observation of a Relaxed Plasma State in a Quasi-Infinite Cylinder

Exploiting Laboratory and Heliophysics Plasma Synergies

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