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Apr 8, 2014 – “Kinetic Simulations of Current Sheets for Different Stellar Magnetospheres”


Speaker:Carrie Black (Goddard)
Date:Apr 8, 2014
Time:4:00 PM
Location:LASP Space Science Building, room N248 upstairs. Map

Seminar Abstract:

Current sheets are ubiquitous features in stellar atmospheres and exist across kinetic and MHD regimes. In the solar corona, the kinetic scales are far removed from the MHD scales, however, kinetic scale dynamics are believed to be important in diffusion regions where magnetic reconnection occurs. In pulsar magnetospheres, where relativistic pair plasmas exist, these scales are not widely separated as the Debye length can be on the order of the skin depth. The goal of the projects presented here is to study current sheet formation and magnetic reconnection in these very different environments using the particle-in-cell Plasma Simulation Code, PSC.

In the first part of this presentation, the pulsar magnetosphere is discussed. A dominant feature is an electric field, whose strength can be comparable to that of the magnetic field in the relativistic limit. We implement a new electrified Harris/Hoh solution (DeVore et al. 2014 (AAS) and expect its presence to have profound consequences for the linear stability and nonlinear evolution of charged pulsar current sheets, substantially modifying the tearing and reconnection of the magnetic field.

In the second part of this presentation, the driving of reconnection through shearing of the magnetic field is discussed. In the standard model for coronal mass ejections (CME) and/or solar flares, the free energy for the event resides in the strongly sheared magnetic field of a filament channel. The pre-eruption force balance is widely believed to be disrupted by magnetic reconnection. In MHD simulations, the application of a magnetic-field shear is a trivial matter. However, the implementation of a shear driver in PIC methods is nontrivial. In the work presented here, we discuss methods for applying a velocity shear perpendicular to the plane of reconnection in a system with open boundary conditions.

This material is based upon work supported by the National Science Foundation under Award No. AGS-1331356 and by NASA GSFC’s Science Innovation Fund.