A plasmoid is a coherent structure of plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning, 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,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. solar atmosphere, and in the heliospheric current sheet. Plasmoids produced in the laboratory include the compact toroids (similar to a vortex ring in low temperature fluid dynamics or hydrodynamics) field-reversed configurations, spheromaks, and filamentary variants in dense plasma focuses.
The word plasmoid was coined in 1956 by Winston H. Bostick (1916–1991) to mean a "plasma-magnetic entity":
Characteristics
Bostick researched the basic traits, and many details, of plasmoids.
A plasmoid has an internal pressure stemming from both the gas pressure of the plasma and the magnetic pressure of the field. To maintain an approximately static plasmoid radius, this pressure must be balanced by an external confining pressure. In a field-free vacuum, a plasmoid expands and dissipates rapidly.
Plasmoids have been formed in discharges with local magnetic field strengths on the order of 16,000 tesla.
Astronomic 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, December 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, December 1986, p. 703–717.
Footnotes
References 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.
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