P. A. Cassak

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A catastrophe model for the onset of fast magnetic reconnection is presented that suggests why plasma systems with magnetic free energy remain apparently stable for long times and then suddenly release their energy. For a given set of plasma parameters there are generally two stable reconnection solutions: a slow (Sweet-Parker) solution and a fast(More)
We demonstrate the existence of a new steady-state magnetic reconnection configuration which lies at the boundary of the basins of attraction between the Sweet-Parker and Hall reconnection configurations. The solution is linearly unstable to small perturbations and its identification required a novel iterative numerical technique. The eigenmodes of the(More)
There is currently no explanation of why the corona has the temperature and density it has. We present a model which explains how the dynamics of magnetic reconnection regulates the conditions in the corona. A bifurcation in magnetic reconnection at a critical state enforces an upper bound on the coronal temperature for a given density. We present(More)
Formulas for the expansion of arbitrary invariant group functions in terms of the characters for the Sp(2N), SO(2N + 1), and SO(2N) groups are derived using a combinatorial method. The method is similar to one used by Balantekin to expand group functions over the characters of the U (N) group. All three expansions have been checked for all N by using them(More)
The nonlinear dynamics of magnetic reconnection in turbulence is investigated through direct numerical simulations of decaying, incompressible, two-dimensional magnetohydrodynamics. Recently, it was shown by Servidio et al. ͓Phys. Rev. Lett. 102, 115003 ͑2009͔͒ that in fully developed turbulence complex processes of reconnection occur locally. Here, the(More)
Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found(More)
We present a theory and numerical evidence for the existence of a previously unexplored in-plane electric field in collisionless asymmetric magnetic reconnection. This electric field, dubbed the "Larmor electric field," is associated with finite Larmor radius effects and is distinct from the known Hall electric field. Potentially, it could be an important(More)
The simulation was performed using the P3D code [Zeiler et al. 2002]. The simulation data are presented in a coordinate system that is directly comparable to GSE. The simulation is 2.5 dimensional (∂/∂y) = 0, and the (x,z) domain is 20.48 x 40.96 (grid scale 0.01) in distance units normalized to the magnetosheath ion inertial length. The ion to electron(More)