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p3d: Magnetic Reconnection via an Electromagnetic PIC Code

p3d: Magnetic Reconnection via an Electromagnetic PIC Code. Marc Swisdak IREAP, University of Maryland NERSC User Group Meeting Argonne National Laboratory May 29, 2003. One of Many Codes. J. Drake, M. Shay Magnetic Reconnection Hall MHD B. Dorland Collisionless magnetized turbulence

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p3d: Magnetic Reconnection via an Electromagnetic PIC Code

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  1. p3d: Magnetic Reconnection via an Electromagnetic PIC Code Marc Swisdak IREAP, University of Maryland NERSC User Group Meeting Argonne National Laboratory May 29, 2003

  2. One of Many Codes • J. Drake, M. Shay Magnetic Reconnection • Hall MHD • B. Dorland Collisionless magnetized turbulence • Gyrokinetic • B. Kleva Tokamak edge turbulence • Braginskii fluid

  3. Magnetic Reconnection: A process whereby magnetic energy, |B|2, is converted into thermal and kinetic energy, kBT and ρ|v|2.

  4. Vin Vout B Cartoon Reconnection

  5. Magnetic Reconnection is Ubiquitous

  6. Q: Why PIC? A: It’s closer to the real physics. • The major alternative, MHD, is a fluid approximation. It only agrees with real-life reconnection after some unnatural tweaking. • Small spatial and short temporal scales, turbulence and wave-particle interactions in particular, are completely missed.

  7. Equations Maxwell Newton-Lorentz

  8. Algorithms • Gridded electromagnetic fields advanced by trapezoidal leapfrog, the (possibly relativistic) particles with a Boris algorithm. • Discretization errors accumulate to form a secular violation of Poisson’s equation: • This can be solved via FFTs, but they make BCs more difficult and have some parallelization issues. The multigrid treats the different scales on different grids, each with an appropriate timestep.

  9. Scaling •  50% slower at 1024 than at 16 processors • Efficiency: About 20% of maximum at 1 processor,  8% for 1024 processors

  10. 3-D Magnetic Reconnection • Recent work: Drake et al. “Formation of Electron Holes and Particle Energization in Magnetic Reconnection”, Science, 299, 873, 2003. • Followup run: 15 hours on 64 nodes (1024 processors) Jz

  11. Turbulence at the X-line • Electron holes and associated wave-particle interactions can have a significant effect on the progression of reconnection. Ez

  12. Future Challenges • Comparisons with data • Particle heating • Observations of turbulence • Larger domains • Connect with fluid codes • What can be said about the global aspects of reconnection? • Managing output • Movies • Initialization/restart files

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