Spontaneous onset of magnetic reconnection in toroidal plasma caused by breaking of 2D symmetry

Journal Article · Tue Nov 15 04:00:00 EST 2011 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3626837· OSTI ID:22047033

Egedal, Jan; Katz, Noam; Bonde, Jeff; Fox, Will; Le, Ari; Porkolab, Miklos; Vrublevskis, Arturs ^[1]

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1. Department of Physics/Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

Magnetic reconnection is studied in the collisionless limit at the Versatile Toroidal Facility (VTF) at MIT. Two distinct magnetic configurations are applied in the experiments; an open magnetic cusp and a closed cusp. In the open cusp configurations, the field lines intersect the the vacuum vessel walls and here axisymmetric oscillatory reconnection is observed. Meanwhile, in the closed cusp configuration, where the field lines are confined inside the experiment, the coupling between global modes and a current sheet leads to powerful bursts of 3D spontaneous reconnection. These spontaneous events start at one toroidal location, and then propagate around the toroidal direction at the Alfven speed (calculated with the strength of the dominant guide field). The three dimensional measurements include the detailed time evolution of the plasma density, current density, the magnetic flux function, the electrostatic potential, and the reconnection rate. The vastly different plasma behavior in the two configurations can be described using a simple theoretical framework, linking together the interdependencies of the reconnection rate, the in-plane electrostatic potential, and the parallel electron currents. We find that it is the breaking of toroidal symmetry by the global mode that allows for a localized disruption of the x-line current and hereby facilitates the onset of spontaneous reconnection.

• OSTI ID: 22047033
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 18; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
AXIAL SYMMETRY
CHARGED-PARTICLE TRANSPORT
COUPLING
CURRENT DENSITY
ELECTRONS
MAGNETIC CONFINEMENT
MAGNETIC FLUX
MAGNETIC RECONNECTION
MAGNETOHYDRODYNAMICS
PLASMA
PLASMA DENSITY
PLASMA INSTABILITY
THREE-DIMENSIONAL CALCULATIONS
TOKAMAK DEVICES