Bulletin of the American Physical Society
2016 Annual Meeting of the APS Mid-Atlantic Section
Volume 61, Number 16
Saturday–Sunday, October 15–16, 2016; Newark, Delaware
Session D1: Plasma and Space Physics |
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Chair: Debanjan Sengupta, University of Delaware Room: Sharp Laboratory 123 |
Saturday, October 15, 2016 4:00PM - 4:12PM |
D1.00001: The Effect of Parallel Electric Fields on Ion Heating in Magnetic Reconnection Colby Haggerty The structure and corresponding temperature of ion velocity distribution functions are examined as they encounter magnetic reconnection exhausts. For even modest ion beta ($\beta_i \approx 1$) we find that a significant upstream ion population will not reach the midplane. These modified exhaust distribution functions will affect the total heating due to reconnection. We then include the effect of the effective potential associated with field aligned electric fields described in Haggerty et. al 2015 to numerically calculate the ion heating prediction. This prediction is compared with numerous simulations and it is found to be consistent with ion heating in the exhaust. [Preview Abstract] |
Saturday, October 15, 2016 4:12PM - 4:48PM |
D1.00002: Turbulence and Fusion at the Tri-Co: Plasma Research at Bryn Mawr College and Swarthmore College Invited Speaker: D.A. Schaffner Existing and planned experiments at Swarthmore College and Bryn Mawr College focus on the physics of magnetohydrodynmaic (MHD) turbulence and magneto-inertial fusion (MIF). In the Swarthmore Spheromak Experiment (SSX) at Swarthmore College, dynamic magnetized plasma is generated using a plasma gun source and launched into a long cylindrical tube called the plasma wind tunnel. The turbulent nature of this plasma is investigated through statistical analyses of measured magnetic and velocity fluctuations. An upgraded turbulence experiment is in development at Bryn Mawr College focusing on generating long-pulse, highly spatially-resolved turbulent plasma. Results of these turbulent analyses are compared to satellite observations of the solar wind and edge turbulence in the Large Plasma Device (LAPD) at UCLA. The end-state state of this turbulent process is a helically twisted magnetic structure called a Taylor state. The structure is being investigated as both a potential driver and a target for magneto-inertial fusion through the ARPA-E ALPHA program. [Preview Abstract] |
Saturday, October 15, 2016 4:48PM - 5:00PM |
D1.00003: Super-Alfv\'{e}nic Propagation and Damping of Reconnection Onset Signatures. Prayash Sharma Pyakurel The onset of magnetic reconnection in the magnetotail has far reaching consequences for the dynamics of the magnetosphere. However, our understanding of the dynamics of onset as well as when and where it occurs in the magnetosphere is incomplete. One of the fastest propagating signatures of reconnection onset is the quadrupolar Hall magnetic field that has been shown to be a Kinetic Alfv\'{e}n Wave (KAW). These KAWs propagate extremely fast away from the reconnection site, carry substantial amounts of energy in the form of Poynting flux and electron flows, and may be responsible for electron acceleration and the generation of aurora. If this KAW propagation can be well understood, then this will provide valuable insight as to the relative timing of substorm onset versus reconnection onset in the magnetotail. However, to date there has not been a study of how reconnection generated KAWs will damp and disperse as they propagate. Using large scale kinetic particle-in-cell (PIC) simulations of reconnection we investigate the damping of the KAWs as they propagate away from the x-line. We show that the hall quadrupolar structure dissipates according to linear Landau damping determined from a numerical solution of the linear Vlasov equation. Extending results to magnetotail parameters, we find that only the part of the wave with k c/$\omega_{\mathrm{pi}}$ will damp weakly enough to propagate from the mid-tail to the inner magnetosphere. In solar corona, all KAWs damp before they reach 1R$_{\mathrm{sun}}$. [Preview Abstract] |
Saturday, October 15, 2016 5:00PM - 5:12PM |
D1.00004: Energy transfer down to kinetic scales and the role of pressure tensor in heating of kinetic plasma Yan Yang, William Matthaeus, Tulasi Parashar The classical energy cascade theory suggests that energy is transferred from large to small scales at a constant rate. This scenario is of great importance in explaining the heating of corona and solar wind. One can envision that energy residing in large-scale fluctuations is transported to smaller scales where dissipation occurs and finally drives kinetic processes that absorb the energy flux and energize charged particles. When filtering the Vlasov equation, we can introduce several energy transfer functions across scales. We propose to use kinetic plasma simulations and investigate how the characteristics of energy transfer vary going from MHD to kinetic scales. It has been shown that in compressible MHD turbulence, apart from dissipation, the pressure dilatation can trigger an alternative channel of the conversion between fluid flow energy and thermal energy. We will address the analogous roles of the (tensor) pressure dilatation in collisionless plasma. We study, for example, effects of anisotropic and isotropic pressure, and of the diagonal and off-diagonal pressure tensor, and related influences on dissipation and heating. [Preview Abstract] |
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