Experimental investigation of three-dimensional magnetic reconnection by use of two colliding spheromaks

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860840· OSTI ID:6241072

Ono, Y; Morita, A; Katsurai, M ^[1]; Yamada, M ^[2]

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1. Department of Electrical Engineering, Faculty of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113 (Japan)
2. Princeton University, Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

Experimental investigation of three-dimensional (3-D) effects of magnetic reconnection dynamics has been extended by use of axially colliding spheromaks [M. Yamada [ital et] [ital al]., Phys. Fluids B [bold 3], 2379 (1991)]. The two toroidal shape spheromak plasmas with major radii of 15--20 cm and with parallel toroidal currents of up to 30 kA collide to merge in an external equilibrium field. It is important to note that the present experimental setup allows one to investigate magnetic reconnection comprehensively from both local and global points of view. Reconnection angle [theta] between the merging field lines is varied by changing the polarity of the internal toroidal field and the magnitude of an external toroidal field. It is observed that the speed of counterhelicity merging with [theta][similar to]180[degree] is about three times faster than that of cohelicity merging with [theta][similar to]90[degree]. This suggests the significance of a 3-D effect on the reconnection process. This difference is attributed to the property of the neutral current sheets with and without the magnetic field component parallel to the reconnection (X) line. In the counterhelicity merging, the neutral current sheet is compressed in much shorter time than in the cohelicity merging, resulting in much higher current density and subsequent faster decay of the current sheet. This induces a faster magnetic reconnection. The reconnection speed increases proportionally with the initial approaching speed of the spheromaks, suggesting that a compressible driven reconnection model is consistent with the present reconnection experimental results.

• OSTI ID: 6241072
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 5:10; ISSN PFBPEI; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700370* -- Plasma Fluid & MHD Properties-- (1992-)
CLOSED PLASMA DEVICES
CURRENT DENSITY
FLUID MECHANICS
HELICITY
HYDRODYNAMICS
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
MECHANICS
PARTICLE PROPERTIES
SOLAR ACTIVITY
SOLAR FLARES
SPHEROMAK DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES