The Madison plasma dynamo experiment: A facility for studying laboratory plasma astrophysics

Cooper, C. M.; Wallace, John; Brookhart, Matthew; Clark, Michael; Collins, C.; Ding, Weixing; Flanagan, K.; Khalzov, Ivan; Li, Y.; Milhone, Jason; Nornberg, M. D.; Nonn, P. D.; Weisberg, David B.; Whyte, D.G.; Zweibel, Ellen G.; Forest, C. B.

doi:10.1063/1.4861609

Cited by 45 publications

(52 citation statements)

References 19 publications

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“…The role of the magnetic and generalized helicities in Hall MHD turbulence has never been studied analytically in great detail although it is believed to be important e.g. for the study of the plasma dynamo [5] for which a novel experiment has been designed recently [52].…”

Section: Introductionmentioning

confidence: 99%

Chiral exact relations for helicities in Hall magnetohydrodynamic turbulence

Banerjee

Galtier

2016

Phys. Rev. E

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Besides total energy, three-dimensional incompressible Hall magnetohydrodynamics (MHD) possesses two inviscid invariants which are the magnetic helicity and the generalized helicity. New exact relations are derived for homogeneous (non-isotropic) stationary Hall MHD turbulence (and also for its inertialess electron MHD limit) with non-zero helicities and in the asymptotic limit of large Reynolds numbers. The universal laws are written only in terms of mixed second-order structure functions, i.e. the scalar product of two different increments. It provides, therefore, a direct measurement of the dissipation rates for the corresponding invariant flux. This study shows that the generalized helicity cascade is strongly linked to the left polarized fluctuations while the magnetic helicity cascade is linked to the right polarized fluctuations.

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Section: Introductionmentioning

confidence: 99%

Chiral exact relations for helicities in Hall magnetohydrodynamic turbulence

Banerjee

Galtier

2016

Phys. Rev. E

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“…All models were tested against the expressions (5) and (6) where the filtered nonlinear term is not split into additional components. A split allows to separate different types of interactions between scales: only among resolved scales, between resolved and unresolved scales, and only among unresolved scales.…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, experiments on Earth also aim at a better understanding of e.g. flow-driven MHD instabilities [6]. However, the full multi-dimensional dynamics are only rarely accessible in these observations and experiments.…”

Section: Introductionmentioning

confidence: 99%

Comparative statistics of selected subgrid-scale models in large-eddy simulations of decaying, supersonic magnetohydrodynamic turbulence

et al. 2017

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Large eddy simulations (LES) are a powerful tool in understanding processes that are inaccessible by direct simulations due to their complexity, for example, in the highly turbulent regime. However, their accuracy and success depends on a proper subgrid-scale (SGS) model that accounts for the unresolved scales in the simulation. We evaluate the applicability of two traditional SGS models, namely the eddy-viscosity (EV) and the scale-similarity (SS) model, and one recently proposed nonlinear (NL) SGS model in the realm of compressible MHD turbulence. Using 209 simulations of decaying, supersonic (initial sonic Mach number Ms ≈ 3) MHD turbulence with a shock-capturing scheme and varying resolution, SGS model and filter, we analyze the ensemble statistics of kinetic and magnetic energy spectra and structure functions. Furthermore, we compare the temporal evolution of lower and higher order statistical moments of the spatial distributions of kinetic and magnetic energy, vorticity, current density, and dilatation magnitudes. We find no statistical influence on the evolution of the flow by any model if grid-scale quantities are used to calculate SGS contributions. In addition, the SS models, which employ an explicit filter, have no impact in general. On the contrary, both EV and NL models change the statistics if an explicit filter is used. For example, they slightly increase the dissipation on the smallest scales. We demonstrate that the nonlinear model improves higher order statistics already with a small explicit filter, i.e. a three-point stencil. The results of e.g. the structure functions or the skewness and kurtosis of the current density distribution are closer to the ones obtained from simulations at higher resolution. In addition, no additional regularization to stabilize the model is required. We conclude that the nonlinear model with a small explicit filter is suitable for application in more complex scenarios when higher order statistics are important.

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“…The plasma collisionality thus allows for an efficient flow drive from the azimuthal J × B torque. Flow drive in other experiments with similar plasma parameters also rely on finite perpendicular plasma conductivity (Klinger et al 1997;Annaratone et al 2011;Collins et al 2012;Zhou et al 2012;Cooper et al 2014).…”

Section: Machine Description and Capabilitiesmentioning

confidence: 99%

Flow dynamics and magnetic induction in the von-Kármán plasma experiment

et al. 2014

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The von-Kármán plasma experiment is a novel versatile experimental device designed to explore the dynamics of basic magnetic induction processes and the dynamics of flows driven in weakly magnetized plasmas. A high-density plasma column (10 16 -10 19 particles. m −3 ) is created by two radio-frequency plasma sources located at each end of a 1 m long linear device. Flows are driven through J × B azimuthal torques created from independently controlled emissive cathodes. The device has been designed such that magnetic induction processes and turbulent plasma dynamics can be studied from a variety of time-averaged axisymmetric flows in a cylinder. MHD simulations implementing volume-penalization support the experimental development to design the most efficient flow-driving schemes and understand the flow dynamics. Preliminary experimental results show that a rotating motion of up to nearly 1 km/s is controlled by the J × B azimuthal torque.

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The Madison plasma dynamo experiment: A facility for studying laboratory plasma astrophysics

Cited by 45 publications

References 19 publications

Chiral exact relations for helicities in Hall magnetohydrodynamic turbulence

Chiral exact relations for helicities in Hall magnetohydrodynamic turbulence

Comparative statistics of selected subgrid-scale models in large-eddy simulations of decaying, supersonic magnetohydrodynamic turbulence

Flow dynamics and magnetic induction in the von-Kármán plasma experiment

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