High-Frequency Fluctuations During Magnetic Reconnection

Monday, 15 December 2014: 11:50 AM
Jonathan Jara-Almonte1, Hantao Ji2, William S Daughton3, Vadim Roytershteyn4, Masaaki Yamada1, Jongsoo Yoo1 and William R Fox II1, (1)Princeton University, Princeton, NJ, United States, (2)Princeton Univ, Princeton, NJ, United States, (3)MS-F699, Plasma Theory and App, Los Alamos, NM, United States, (4)SciberQuest, Inc, Atlanta, GA, United States
During collisionless reconnection, the decoupling of the field from the plasma is known to occur only within the localized ion and electron diffusion regions, however predictions from fully kinetic simulations do not agree with experimental observations on the size of the electron diffusion region, implying differing reconnection mechanisms. Previous experiments, along with 2D and 3D simulations, have conclusively shown that this discrepancy cannot be explained by either classical collisions or Lower-Hybrid Drift Instability (Roytershtyn 2010, 2013). Due to computational limitations, however, previous simulations were constrained to have minimal scale separation between the electron skin depth and the Debye length (deD ~ 10), much smaller than in experiments (deD ~ 300). This lack of scale-separation can drastically modify the electrostatic microphysics within the diffusion layer. Using 3D, fully explicit kinetic simulations with a realistic and unprecedentedly large separation between the Debye length and the electron skin depth, deD = 64, we show that high frequency electrostatic waves (ω >> ωLH) can exist within the electron diffusion region. These waves generate small-scale turbulence within the electron diffusion region which acts to broaden the layer. Anomalous resistivity is also generated by the turbulence and significantly modifies the force balance. In addition to simulation results, initial experimental measurements of high frequency fluctuations (electrostatic and electromagnetic, f ≤ 1 GHz) in the Magnetic Reconnection Experiment (MRX) will be presented.