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for Magnetic Reconnection Studies
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Figure
12 Flux surface plot on the (x, z)
plane from a Hall MHD simulation indicating schematically
the width 
and length 
of the reconnection layer. |
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The goal of this project is the development of high-performance
computing tools that will elucidate the physics of magnetic
reconnection, and apply these tools to the solution of outstanding
problems in fusion and astrophysical plasma physics.
During the last four decades, two models of steady-state
reconnection—Sweet-Parker and Petschek—have been
the focal points of discussions on nonlinear reconnection
dynamics. Both models are based on resistive magnetohydrodynamics
(MHD). Computer simulations of high-S plasmas have revealed
strengths and weaknesses in both models. A possible resolution
of this quandary may be found by going beyond the resistive
MHD model and including collisionless effects via the generalized
Ohm’s law.
In a nonlinear Hall MHD simulation under quasisteady conditions,
with a reconnection layer of length 
and width 
(Figure 12), no current theory calculates the important length
parameter
from first principles. Wang et al. recently attempted to settle
this question by determining analytically the dependency of
the parameter
on local and global parameters for a model of forced reconnection.
They obtained an explicit analytical expression for ,
which is much smaller than the system size, and identified
its dependencies on local plasma parameters as well as global
parameters determined by boundary conditions. They also tested
the analytical scaling by simulations using the University
of Iowa (UI) Hall MHD code.
INVESTIGATORS
A. Bhattacharjee, N. Bessho, B. Chandran, K. Germaschewski,
Z. W. Ma, C. S. Ng, and P. Zhu, University of Iowa; F. Cattaneo,
T. Linde, R. Rosner, and A. Siegel, University of Chicago;
R. Fitzpatrick and P. Watson, University of Texas, Austin.
PUBLICATION
X. Wang, A. Bhattacharjee, and Z. W. Ma, “Scaling of
collisionless forced reconnection,” Phys. Rev. Lett.
87, 265003 (2001).
URL
http://reconnection.sr.unh.edu/ |
