Driven magnetic reconnection near the Dreicer limit

Journal Article · Sat May 15 04:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3399787· OSTI ID:21371181

Roytershteyn, V; Daughton, W; Yin, L; Albright, B J; Bowers, K J ^[1]; Dorfman, S; Ren, Y; Ji, H; Yamada, M ^[2]; Karimabadi, H ^[3]

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1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2. Center for Magnetic Self-organization in Laboratory and Astrophysical Plasmas, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
3. University of California, San Diego, La Jolla, California 92093 (United States)

The influence of Coulomb collisions on the dynamics of driven magnetic reconnection in geometry mimicking the Magnetic Reconnection eXperiment (MRX) [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] is investigated using two-dimensional (2D) fully kinetic simulations with a Monte Carlo treatment of the collision operator. For values of collisionality typical of MRX, the reconnection mechanism is shown to be a combination of collisionless effects, represented by off-diagonal terms in the electron stress tensor, and collisional momentum exchange between electrons and ions. The ratio of the reconnection electric field E{sub R} to the critical runaway field E{sub crit} provides a convenient measure of the relative importance of these two mechanisms. The structure of electron-scale reconnection layers in the presence of collisions is investigated in light of the previously reported [S. Dorfman et al., Phys. Plasmas 15, 102107 (2008)] discrepancy in the width of the electron reconnection layers between collisionless simulations and experimental observations. It is demonstrated that the width of the layer increases in the presence of collisions, but does not substantially deviate from its collisionless values, given by the electron crossing orbit width, unless E{sub R}<<E{sub crit}. Comparison with MRX observations demonstrates that the layer width in 2D simulations with Coulomb collisions is substantially smaller than the value observed in the low-density experiments with E{sub R} < or approx. E{sub crit}, indicating that physical mechanisms beyond those included in the simulations control the structure of the electron layers in these experiments.

• OSTI ID: 21371181
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 17; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CALCULATION METHODS
COLLISIONS
DIMENSIONS
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
LAYERS
LEPTONS
MAGNETIC RECONNECTION
MONTE CARLO METHOD
PLASMA SIMULATION
SIMULATION
TWO-DIMENSIONAL CALCULATIONS
WIDTH