plasmoid

{{Short description|Plasma and magnetic field structure}}

{{about|the physics phenomenon|the computer software feature|KDE Plasma 5#Desktop features|the DNA molecule|plasmid}}

File:Plasmoid.jpg]]

A plasmoid is a coherent structure of plasma and magnetic fields. Plasmoids have been proposed to explain natural phenomena such as ball lightning,{{cite journal |last1=Silberg |first1=Paul A.|title=Ball lightning and plasmoids |journal=Journal of Geophysical Research |date=November 1962 |volume=67 |issue=12 |pages=4941–4942 |doi=10.1029/JZ067i012p04941 |bibcode=1962JGR....67.4941S}}{{cite journal |last1=Friday |first1=DM |last2=Broughton |first2=PB |last3=Lee |first3=TA |last4=Schutz |first4=GA |last5=Betz |first5=JN |last6=Lindsay |first6=CM |title=Further insight into the nature of ball-lightning-like atmospheric pressure plasmoids |journal=The Journal of Physical Chemistry A |date=3 October 2013 |volume=117 |issue=39 |pages=9931–40 |pmid=23767686 |doi=10.1021/jp400001y |bibcode=2013JPCA..117.9931F}} 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,{{cite journal |last1=Lemaire |first1=J. |last2=Roth |first2=M. |date=26 March 1981 |title=Differences between solar wind plasmoids and ideal magnetohydrodynamic filaments |url=https://ui.adsabs.harvard.edu/abs/1981P%26SS...29..843L/abstract |journal=Planetary and Space Science |volume=29 |issue=8 |pages=843–849 |doi=10.1016/0032-0633(81)90075-1 |bibcode=1981P&SS...29..843L}}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,{{cite journal |last1=Cargill |first1=P. J. |last2=Pneuman |first2=G. W. |date=August 15, 1986 |url=https://ui.adsabs.harvard.edu/abs/1986ApJ...307..820C/abstract |title=The energy balance of plasmoids in the solar atmosphere |journal=Astrophysical Journal, Part 1 |volume=307 |pages=820–825 |issn=0004-637X}} 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":{{cite journal |last1=Bostick |first1=Winston H |year=1956 |title=Experimental Study of Ionized Matter Projected across a Magnetic Field |url=https://ui.adsabs.harvard.edu/abs/1956PhRv..104..292B/abstract |journal=Physical Review |volume=104 |issue=2 |pages=292–299 |doi=10.1103/physrev.104.292 |bibcode=1956PhRv..104..292B}}

{{Blockquote|text=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.|author=Winston H. Bostick}}