Physical Review Letters -- April 21, 1997 -- Volume 78, Issue 16, pp. 3117-3120


Identification of Y-Shaped and O-Shaped Diffusion Regions During Magnetic Reconnection in a Laboratory Plasma
Masaaki Yamada, Hantao Ji, Scott Hsu, Troy Carter, Russell Kulsrud, Yasushi Ono, and Francis Perkins
Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543

(Received 11 November 1996; revised 17 January 1997)

Two strikingly different shapes of diffusion regions are identified during magnetic reconnection in a magnetohydrodynamic laboratory plasma. The shapes depend on the third vector component of the reconnecting magnetic fields. Without the third component (antiparallel or null-helicity reconnection), a thin double-Y-shaped diffusion region is identified. In this case, the neutral sheet current profile is accurately measured to be as narrow as the order of the ion gyro-radius. In the presence of an appreciable third component (cohelicity reconnection), an O-shaped diffusion region appears and grows into a spheromak configuration.

PACS: 52.30.Jb, 94.30.Lr, 96.60.Rd

Full paper: pdf file (238 Kb).

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