Liquid metal current collectors for homopolar machines

Johnson, John L.; Hummert, G. T.; Keeton, A. R.

doi:10.1109/t-pas.1976.32217

Cited by 12 publications

(1 citation statement)

References 2 publications

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“…This can be achieved by introduction of filters and spare liquid reservoirs into the recirculation loop. The SEGMAG prototype by Westinghouse Research Laboratories (3000 HP, 107 kA and 20 V) was also equipped by a NaK loop for recirculation and purification of the liquid, which allowed up to 9000 h continuous operation with various contamination levels of cover gas [12], [13].…”

Section: Liquid Metal Sliding Contactmentioning

confidence: 99%

A superconducting homopolar motor and generator—new approaches

Fuger¹,

Matsekh²,

Kells³

et al. 2016

Supercond. Sci. Technol.

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Homopolar machines were the first continuously running electromechanical converters ever demonstrated but engineering challenges and the rapid development of AC technology prevented wider commercialisation. Recent developments in superconducting, cryogenic and sliding contact technology together with new areas of application have led to a renewed interest in homopolar machines. Some of the advantages of these machines are ripple free constant torque, pure DC operation, high power-to-weight ratio and that rotating magnets or coils are not required. In this paper we present our unique approach to high power and high torque homopolar electromagnetic turbines using specially designed high field superconducting magnets and liquid metal current collectors. The unique arrangement of the superconducting coils delivers a high static drive field as well as effective shielding for the field critical sliding contacts. The novel use of additional shielding coils reduces weight and stray field of the system. Liquid metal current collectors deliver a low resistance, stable and low maintenance sliding contact by using a thin liquid metal layer that fills a circular channel formed by the moving edge of a rotor and surrounded by a conforming stationary channel of the stator. Both technologies are critical to constructing high performance machines. Homopolar machines are pure DC devices that utilise only DC electric and magnetic fields and have no AC losses in the coils or the supporting structure. Guina Energy Technologies has developed, built and tested different motor and generator concepts over the last few years and has combined its experience to develop a new generation of homopolar electromagnetic turbines. This paper summarises the development process, general design parameters and first test results of our high temperature superconducting test motor.

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Section: Liquid Metal Sliding Contactmentioning

confidence: 99%

A superconducting homopolar motor and generator—new approaches

Fuger¹,

Matsekh²,

Kells³

et al. 2016

Supercond. Sci. Technol.

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A homopolar motor for the demonstration of new high current brushes

Reichner

Doshi

1982

Wear

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Magnetohydrodynamic liquid-metal flows and power losses in a rectangular channel with a moving conducting wall

Brown

Reilly

Sondergaard

1987

Journal of Applied Physics

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Fully developed, viscous liquid-metal flows and power losses in a rectangular channel in a uniform, external magnetic field were studied for moderate Hartmann numbers and different channel aspect ratios. The channel was assumed to have insulating side walls parallel to the field, a perfectly conducting moving top wall, and a stationary bottom wall perpendicular to the field. Exact series solutions and numerical calculations are presented for velocity profiles, induced magnetic field distributions, current densities, voltage profiles, and viscous and joulean power losses. The joulean and viscous dissipation are computed from squared quantities involving infinite series with double summations for finite M. The diverging series derived for the viscous power losses is made convergent by slightly modifying the velocity profile of the conducting fluid at the moving interface. The effect of the applied field is to produce an eddy current that accelerates the bulk fluid to velocities greater than those without the field, but because of the presence of the side walls, the velocities are less than in one-dimensional couette flow. Except at small aspect ratios and Hartmann number, almost the entire power loss resulted from the component of the induced current parallel to the applied field.

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Liquid metal current collectors for homopolar machines

Cited by 12 publications

References 2 publications

A superconducting homopolar motor and generator—new approaches

A superconducting homopolar motor and generator—new approaches

A homopolar motor for the demonstration of new high current brushes

Magnetohydrodynamic liquid-metal flows and power losses in a rectangular channel with a moving conducting wall

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