A publication of the Advanced Simulation & Computing Division, NA-121.2, NNSA Defense Programs
June 2009
NA-ASC-500-09—Issue 11
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New Scientific Insights on Magnetic Reconnection from Roadrunner Open Science Runs
As mentioned in the March 2009 issue of the ASC eNews, Los Alamos is conducting open-science runs on the Roadrunner petascale supercomputer. One of the science topics under investigation concerns magnetic reconnection, a basic plasma process in which magnetic field energy is rapidly converted into plasma kinetic energy. Understanding these basic structural features will allow researchers to better predict the dissipation rate and time dependence of reconnection for a variety of applications. Initial simulations of magnetic reconnection using the particle-in-cell code, VPIC, are leading to new scientific insights into the influence of plasma instabilities on the 3D evolution of reconnection layers. Go to http://www.lanl.gov/roadrunner/rropenscienceabstracts.shtml to see the abstract for this project “Three-Dimensional Dynamics of Magnetic Reconnection in Space and Laboratory Plasmas.” Principal Investigator, Bill Daughton, from the Applied Physics Division at Los Alamos is leading this project.
Although the team has not yet been able to run at full scale (17 connected units), there has been some limited success at reduced scale for two types of reconnection problems. First, they are employing boundary conditions relevant to the Magnetic Reconnection eXperiment (MRX) to allow direct validation comparisons regarding the kinetic structure of the layer. One 3D simulation of this type at 1/8 of the full-scale has demonstrated a plasma instability within the electron layer, which may play an important role. The second class of problem employs open boundary conditions to model magnetic reconnection in large open systems for application to space and astrophysical plasmas. The graphic and movie show preliminary results of two types of plasma instabilities within the electron region of the reconnection layer and the complex 3D interaction of flux ropes. The team is working to understand the role these instabilities play in setting the dissipation rate and accelerating electrons to high energy. The movie rotates through a particular time slice to show the complex interaction of flux ropes for a reconnection simulation of the “open boundary” type. They are preparing to perform full-scale runs for both of these problems.
Preliminary results of two types of plasma instabilities within the electron region of the reconnection layer (top) and the complex 3D interaction of flux ropes (bottom).
Click image to see animation of flux ropes. (Requires Quicktime for viewing).
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