Experimental Investigations of Magneto-Hydrodynamic Waves

Lundquist, S.

doi:10.1103/physrev.76.1805

Cited by 110 publications

(31 citation statements)

References 6 publications

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“…The existence of the wave was experimentally verified by Lundquist [2]. The importance of the AWs was soon realized and since then a lot of studies have been done for space, astrophysical and laboratory plasmas (see [3,4]).…”

Section: Introductionmentioning

confidence: 99%

Particle simulation of plasma heating by a large-amplitude shear Alfvén wave through its transverse modulation in collisionless plasmas

et al. 2005

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Section: Introductionmentioning

confidence: 99%

Particle simulation of plasma heating by a large-amplitude shear Alfvén wave through its transverse modulation in collisionless plasmas

et al. 2005

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“…However, Alfvén waves might be generated when either the Hartmann number is sufficiently high or strong current pulses are injected into the flow. Their propagation along the magnetic field is governed by the Lundquist number S = Ha Pr 1/2 m (Lundquist 1949), where Pr m is the magnetic Prandtl number. For liquid metals, the quasi-static approximation holds when Ha O(10 3 ) (Pothérat & Kornet 2015).…”

Section: Computational Set-upmentioning

confidence: 99%

Combining an obstacle and electrically driven vortices to enhance heat transfer in a quasi-two-dimensional MHD duct flow

2016

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The design of vortex promoters in a heated-wall duct is often limited by the considerations of practicality, especially in complex systems such as fusion blankets. The present study investigates the use of current injection to invoke a street of vortices in quasi-two-dimensional high transverse magnetic field magnetohydrodynamic duct flows to enhance instability behind a cylinder. The intent is to generate intensive flow vorticity parallel to a magnetic field downstream of a field-aligned cylinder. Electric current enters the flow through an electrode embedded in one of the Hartmann walls, radiates outward, imparting a rotational forcing around the electrode due to the Lorentz force. The quasi-two-dimensional nature of these flows then promotes a vortical rotation across the interior of the duct with axis aligned to the magnetic field. The hot and cold walls are parallel to the magnetic field. Electric current amplitude and pulse width, excitation frequency and electrode position are systematically varied to explore their influences on the convective heat transport phenomenon. This investigation builds on a recommendation from previous work of Bühler (J. Fluid Mech., vol. 326, 1996, pp. 125-150) dedicated to understanding of the flow stability in a similar configuration. This study provides supportive evidence for the use of current injection as an alternative to the conventional mechanically actuated turbuliser, with heat transfer almost doubled for negligible additional pumping power requirements.

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“…After Alfvén [34], MHD waves (Alfvén and magnetoacoustic) have been detected, using the laboratory experiments Alfvén wave (e.g. [35][36][37], in the earth-ionosphere and magnetic field [38,39], a variety normal modes of the solar corona [40][41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Magnetoacoustic and Alfvénic black holes

2018

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We introduce analogue black holes (BHs) based on ideal magnetohydrodynamic equations. Similar to acoustic BHs, which trap phonons and emit Hawking radiation (HR) at the sonic horizon where the flow speed changes from super-to sub-sonic, in the horizon of magnetoacoustic and Alfvénic BHs, the magnetoacoustic and Alfvén waves will be trapped and emit HR made of quantized vibrations similar to phonons which we call magnephonons and Alphonons. We proposed that magnetoacoustic and Alfvénic BHs may be created in the laboratory using a tube with variable cross section embedded in a uniform magnetic field, and a supermagnetoacoustic or a super-Alfvénic flow. We show that the Hawking temperature for both BHs is a function of the background magnetic field, number density of fluid, and radius of the tube. For a typical setup, the temperature is estimated to be about 0.0266 K.

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Experimental Investigations of Magneto-Hydrodynamic Waves

Cited by 110 publications

References 6 publications

Particle simulation of plasma heating by a large-amplitude shear Alfvén wave through its transverse modulation in collisionless plasmas

Particle simulation of plasma heating by a large-amplitude shear Alfvén wave through its transverse modulation in collisionless plasmas

Combining an obstacle and electrically driven vortices to enhance heat transfer in a quasi-two-dimensional MHD duct flow

Magnetoacoustic and Alfvénic black holes

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