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On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun

Hsu, S. C. and Bellan, P. M. (2005) On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun. Physics of Plasmas, 12 (3). Art. No. 032103. ISSN 1070-664X. http://resolver.caltech.edu/CaltechAUTHORS:HSUpop05a

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Abstract

Measurements of the various plasma configurations produced by a planar magnetized coaxial gun provide insight into the magnetic topology evolution resulting from magnetic helicity injection. Important features of the experiments are a very simple coaxial gun design so that all observed geometrical complexity is due to the intrinsic physical dynamics rather than the source shape and use of a fast multiple-frame digital camera which provides direct imaging of topologically complex shapes and dynamics. Three key experimental findings were obtained: (1) formation of an axial collimated jet [Hsu and Bellan, Mon. Not. R. Astron. Soc. 334, 257 (2002)] that is consistent with a magnetohydrodynamic description of astrophysical jets, (2) identification of the kink instability when this jet satisfies the Kruskal-Shafranov limit, and (3) the nonlinear properties of the kink instability providing a conversion of toroidal to poloidal flux as required for spheromak formation by a coaxial magnetized source [Hsu and Bellan, Phys. Rev. Lett. 90, 215002 (2003)]. An interpretation is proposed for how the n = 1 central column instability provides flux amplification during spheromak formation and sustainment, and it is shown that jet collimation can occur within one rotation of the background poloidal field.


Item Type:Article
Additional Information:©2005 American Institute of Physics. Received 26 May 2004; accepted 4 November 2004; published online 4 February 2005. The authors acknowledge S. Pracko, C. Romero-Talamás, F. Cosso, and D. Felt for technical assistance and also Dr. S. Woodruff for discussions about past work on spheromak n=1 central column instabilities. This work was supported by U.S. Department of Energy (DOE) Fusion Energy Sciences Postdoctoral Fellowship and DOE Grant No. DE-FG03-98ER544561. Author preprint: arXiv:physics/0411089
Subject Keywords:plasma jets; kink instability; plasma toroidal confinement; plasma guns; plasma diagnostics; plasma magnetohydrodynamics; plasma nonlinear processes
Record Number:CaltechAUTHORS:HSUpop05a
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:HSUpop05a
Alternative URL:http://dx.doi.org/10.1063/1.1850921
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3500
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Jun 2006
Last Modified:26 Dec 2012 08:54

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