Laboratory experiments on shear Alfvén waves and their relationship to space plasmas

Gekelman, Walter; Vincena, S.; Leneman, D.; Maggs, J. E.

doi:10.1029/96ja03683

Cited by 96 publications

(112 citation statements)

References 26 publications

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“…[13] The dispersion relation for kinetic Alfvén waves has been derived by a number of authors [e.g., Lysak and Lotko, 1996;Gekelman et al, 1997;Lysak, 2008]. However, the dispersion relation is written in terms of frequency and wave number, and so is not appropriate for a time domain simulation that can treat the inhomogeneities of the system.…”

Section: Phase Mixing In the Ionospheric Alfvén Resonatormentioning

confidence: 99%

Development of parallel electric fields at the plasma sheet boundary layer

Lysak

Song

2011

J. Geophys. Res.

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[1] Many measurements of auroral particles, in particular recent measurements from the FAST satellite, indicate that the auroral electron distribution is often broad in energy and field-aligned in pitch angle. Such electrons are seen in conjunction with strong kinetic Alfvén waves with small perpendicular wavelength, and so the aurora produced by these electrons has been termed the "Alfvénic aurora." The Alfvénic aurora is predominant at the polar cap boundary of the aurora as well as in the auroral arc that brightens during substorm onset. The process of forming parallel electric fields in Alfvén waves has been investigated by means of three-dimensional two-fluid simulations. Waves with small perpendicular wavelengths can be produced by phase mixing when perpendicular gradients are present in the plasma. At lower altitudes, Alfvén waves can interact with the ionospheric Alfvén resonator and phase mix to scales of a few kilometers. At higher altitudes, the electron thermal speed becomes comparable or larger than the Alfvén speed, and parallel electric fields due to the Landau resonance can develop. This has been modeled in the fluid code by an approximation to the plasma dispersion function used in kinetic theory. Phase mixing is most effective when there are strong gradients, such as at the plasma sheet boundary layer. Simulations indicate that these processes can produce parallel electric fields on scales of a few kilometers (in the cold plasma case) to a few tens of kilometers (in the warm plasma case), comparable to the scale sizes of auroral arcs.

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Section: Phase Mixing In the Ionospheric Alfvén Resonatormentioning

confidence: 99%

Development of parallel electric fields at the plasma sheet boundary layer

Lysak

Song

2011

J. Geophys. Res.

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“…In order to test it, we re-examined a data set taken in an Alfven-wave-propagation experiment that was initially analyzed using AVS. In this experiment, 15 two out-of-phase shear Alfven waves propagated side by side in a magnetoplasma. Since the waves were excited using structures that had dimension, the collisionless skin depth across the magnetic field, the waves propagated as shear-Alfven-wave cones.…”

Section: Experimental Visualizationmentioning

confidence: 99%

Real-time physics data-visualization system using Performer

Mitchell

Gekelman

1998

Computers in Physics

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A data visualization system geared toward large ͑gigabyte or greater-than-gigabyte͒ time-varying scientific data sets has been written. The system is a distributed multiprocessed application that employs techniques used both in the video-game industry and military flight simulators to achieve real-time frame rates. On the computational side, the system calculates vector fields, streamlines, isosurfaces, and cutplanes in real time. The graphics component employs strategic visual database decomposition and levels of detail to maintain a fast frame rate. This allows one to navigate through the data sets as they evolve temporally.

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“…For the shear-mode Alfvén wave, ion polarization current in the direction perpendicular to B 0 is balanced by magnetic-field-aligned current (i.e., parallel) carried by electrons. When λ ⊥ becomes small, comparable to the electron inertial length λ e ≡c/ω pe for the case when β<m e /m i (β=kinetic pressure normalized to magnetic field pressure), or comparable to the ion acoustic gyroradius ρ s = T e /m i /ω ci in higher-β plasma, the parallel electric Correspondence to: S. M. Finnegan (sfinnega@mix.wvu.edu) field becomes significant and the wave becomes dispersive (Goertz and Boswell, 1979;Hasegawa and Uberoi, 1982). In this small-λ ⊥ limit, parallel electron acceleration can result in significant perturbations δB to the background magnetic field B 0 .…”

Section: Introductionmentioning

confidence: 99%

A two-fluid model describing the finite-collisionality, stationary Alfvén wave in anisotropic plasma

Finnegan

Koepke

Knudsen

2008

Nonlin. Processes Geophys.

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Abstract. The stationary inertial Alfvén (StIA) wave (Knudsen, 1996) was predicted for cold, collisionless plasma. The model was generalized to include nonzero values of electron and ion collisional resistivity and thermal pressure. Here, the two-fluid model is further generalized to include anisotropic thermal pressure. A bounded range of values of parallel electron drift velocity is found that excludes periodic stationary Alfvén wave solutions. This exclusion region depends on the value of the local Alfvén speed V A , plasma beta perpendicular to the magnetic field β ⊥ and electron temperature anisotropy.

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Laboratory experiments on shear Alfvén waves and their relationship to space plasmas

Cited by 96 publications

References 26 publications

Development of parallel electric fields at the plasma sheet boundary layer

Development of parallel electric fields at the plasma sheet boundary layer

Real-time physics data-visualization system using Performer

A two-fluid model describing the finite-collisionality, stationary Alfvén wave in anisotropic plasma

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