:for2|Plasma's desktop widgets|Plasma (KDE)A plasmoid is a coherent structure of plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning, [Silberg, Paul A., "Ball Lightning and Plasmoids", (1962) "Journal of Geophysical Research", Vol. 67, p.4941] magnetic bubbles in the magnetosphere, [Hones, E. W., Jr., "The magnetotail - Its generation and dissipation", (1976) "Physics of solar planetary environments"; "Proceedings of the International Symposium on Solar-Terrestrial Physics", Boulder, Colo., June 7-18, 1976. Volume 2.] and objects in cometary tails, [Roosen, R. G.; Brandt, J. C., "Possible Detection of Colliding Plasmoids in the Tail of Comet Kohoutek" (1976), "Study of Comets", Proceedings of IAU Colloq. 25, held in Greenbelt, MD, 28 October - 1 November, 1974. Edited by B. D. Donn, M. Mumma, W. Jackson, M. A'Hearn, and R. Harrington. National Aeronautics and Space Administration SP 393, 1976., p.378] in the solar wind, [Lemaire, J.; Roth, M., [ Differences between solar wind plasmoids and ideal magnetohydrodynamic filaments] "Planetary and Space Science", Volume 29, Issue 8, p. 843-849] [Wang, S.; Lee, L. C.; Wei, C. Q.; Akasofu, S.-I., A mechanism for the formation of plasmoids and kink waves in the heliospheric current sheet (1988) "Solar Physics" (ISSN 0038-0938), vol. 117, no. 1, 1988, p. 157-169.] in the solar atmosphere, [Cargill, P. J.; Pneuman, G. W., " [ The energy balance of plasmoids in the solar atmosphere] " (1986), "Astrophysical Journal", Part 1 (ISSN 0004-637X), vol. 307, Aug. 15, 1986, p. 820-825.] and in the heliospheric current sheet. Plasmoids produced in the laboratory include Field-Reversed Configurations, Spheromaks, and the dense plasma focus.

The word "plasmoid" was coined in 1956 by Winston H. Bostick (1916-1991) to mean a "plasma-magnetic entity":Bostick, Winston H., " [ Experimental Study of Ionized Matter Projected across a Magnetic Field] ", (1956) "Physical Review", vol. 104, Issue 2, pp. 292-299]

The plasma is emitted not as an amorphous blob, but in the form of a torus. We shall take the liberty of calling this toroidal structure a plasmoid, a word which means plasma-magnetic entity. The word plasmoid will be employed as a generic term for all plasma-magnetic entities.

Plasmoid characteristics

Bostick wrote:

Plasmoids appear to be plasma cylinders elongated in the direction of the magnetic field. Plasmoids possess a measurable magnetic moment, a measurable translational speed, a transverse electric field, and a measurable size. Plasmoids can interact with each other, seemingly by reflecting off one another. Their orbits can also be made to curve toward one another. Plasmoids can be made to spiral to a stop if projected into a gas at about 10−3 mm Hg pressure. Plasmoids can also be made to smash each other into fragments. There is some scant evidence to support the hypothesis that they undergo fission and possess spin.

Cosmic applications

Bostick went on to apply his theory of plasmoids to astrophysics phenomena. His 1958 paper, [Bostick, Winston H., " [ Possible Hydromagnetic Simulation of Cosmical Phenomena in the Laboratory] " (1958) "Cosmical Gas Dynamics", Proceedings from IAU Symposium no. 8. Edited by Johannes Martinus Burgers and Richard Nelson Thomas. International Astronomical Union. Symposium no. 8, p. 1090] applied plasma similarity transformations to pairs of plasmoids fired from a plasma gun (dense plasma focus device) that interact in such a way as to simulate an early model of galaxy formation. [W. L. Laurence, "Physicist creates universe in a test tube," "New York Times", p. 1, Dec. 12, 1956.] [Bostick, W. H., " [ What laboratory-produced plasma structures can contribute to the understanding of cosmic structures both large and small] " (1986) "IEEE Transactions on Plasma Science" (ISSN 0093-3813), vol. PS-14, Dec. 1986, p. 703-717.]



* Bostick, W. H., " [ Experimental Study of Plasmoids] ", "Electromagnetic Phenomena in Cosmical Physics", Proceedings from IAU Symposium no. 6. Edited by Bo Lehnert. International Astronomical Union. Symposium no. 6, Cambridge University Press, p.87

ee also

* [ ADS Abstract references]

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