HR: 0800h
AN: SM31D-0663    [Abstracts]
TI: The Role of Electron Heat Flux in Magnetic Reconnection
AU: * Main, D S
EM: dmain@lanl.gov
AF: Los Alamos National Lab, MS F699, Los Alamos, NM 87545, United States
AU: Yin, L
EM: lyin@lanl.gov
AF: Los Alamos National Lab, MS F699, Los Alamos, NM 87545, United States
AU: Winske, D
EM: winske@lanl.gov
AF: Los Alamos National Lab, MS F699, Los Alamos, NM 87545, United States
AU: Bowers, K
EM: kbowers@lanl.gov
AF: Los Alamos National Lab, MS F699, Los Alamos, NM 87545, United States
AB: Particle-in-Cell (PIC) and hybrid simulations (kinetic ions, fluid massless electrons) have been used to investigate magnetic reconnection in 2-D with no guide field. Both simulations are initialized with a Harris sheet equilibrium and the magnetic field is perturbed in order to excite a linear tearing instability. The electron momentum equation is used to calculate the electric field in the hybrid simulation, and the divergence of the full pressure tensor is included in order to break the frozen-in condition at the X-point. In order to evolve the full pressure tensor, we multiply the Vlasov equation by v_iv_j in order to obtain an evolution equation for P_ij. However, this scheme requires knowledge of the divergence of the heat flux (Q), which leads to the well known closure problem in plasma fluid theory. The Hybrid code currently solves the full evolution equation of the electron pressure tensor with the divergence of the heat flux term set to zero. In this paper, we compare the results from the hybrid code with results from the PIC code. Generally the results of the two codes agree, consistent with earlier work. However, we find differences in the evolution of the electron heating and also in the location of the heating. For example, in the hybrid code, the electrons mainly heat in the center of the diffusion region, whereas in the PIC code, the electrons heat at the edge of the diffusion region. To show the effects of the electron heat flux, we calculate it directly from a PIC code and compare with the other source terms in \frac{∂ P}{∂ t}. We show that the heat flux term is as important in determining the electric field as all the other source terms, and therefore cannot be neglected in the calculation of the pressure tensor. Distribution functions are then presented which demonstrate kinetically the source of the heat flux. A scheme is then presented for including heat flux in the hybrid code which does not rely on taking the third moment of the Vlasov equation. Preliminary hybrid results are presented which includes heat flux in the calculation of the momentum equation.
DE: 2744 Magnetotail
DE: 2753 Numerical modeling
DE: 7833 Mathematical and numerical techniques (0500, 3200)
DE: 7839 Nonlinear phenomena (4400, 6944)
DE: 7853 Spacecraft/atmosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting