The Effects of Turbulence on Magnetic Reconnection at the Magnetopause

 dc.contributor.advisor Drake, James F en_US dc.contributor.advisor Swisdak, M M en_US dc.contributor.author Price, Lora en_US dc.date.accessioned 2017-09-14T05:34:26Z dc.date.available 2017-09-14T05:34:26Z dc.date.issued 2017 en_US dc.identifier https://doi.org/10.13016/M24Q7QQ78 dc.identifier.uri http://hdl.handle.net/1903/19876 dc.description.abstract Magnetic reconnection facilitates the conversion of magnetic energy to thermal energy and plasma flows. Reconnection occurs at the magnetopause, the magnetic boundary between the plasmas of the terrestrial magnetosphere and the heliosphere. Turbulence is known to develop at this boundary, but its influence on reconnection, particularly on small scales, is unknown. In light of this, an important goal of NASA's Magnetospheric Multiscale (MMS) Mission is to understand the role turbulence plays in the development of reconnection. We present two- and three-dimensional particle-in-cell simulations of the 16 October 2015 MMS magnetopause reconnection event. While the two-dimensional simulation is laminar, turbulence develops at both the x-line and along the magnetic separatrices in the three-dimensional simulation. This turbulence is electromagnetic, is characterized by a wavevector $k$ given by $k\rho_e\sim(m_e/m_i)^{0.25}$ with $\rho_e$ the electron Larmor radius, and appears to have the ion pressure gradient as its source of free energy. Taken together, these results suggest the instability is a variant of the lower-hybrid drift instability. The turbulence produces electric field fluctuations in the out-of-plane direction with an amplitude of around $\pm 10$ mV/m, which is much greater than the reconnection electric field of around $0.1$ mV/m. Such large values of the out-of-plane electric field have been identified in the MMS data. The turbulence in the simulation controls the scale lengths of the density profile and current layers, driving them closer to $\sqrt{\rho_e\rho_i}$ than the $\rho_e$ or $d_e$ scalings seen in 2D reconnection simulations, where $d_e$ is the electron inertial length. The turbulence produces both anomalous resistivity and anomalous viscosity. Each contribute significantly to breaking the frozen-in condition in the electron diffusion region. The crescent-shaped features in velocity space seen both in MMS observations and in two-dimensional simulations survive. We compare and contrast these results to a three-dimensional simulation of the 8 December 2015 MMS magnetopause reconnection event in which the reconnecting and out-of-plane guide fields are comparable. LHDI is still present in this event, although its appearance is modified by the presence of the guide field. The crescents also survive although, in agreement with MMS, their intensity decreases. Nevertheless, the developing turbulence remains strong. en_US dc.language.iso en en_US dc.title The Effects of Turbulence on Magnetic Reconnection at the Magnetopause en_US dc.type Dissertation en_US dc.contributor.publisher Digital Repository at the University of Maryland en_US dc.contributor.publisher University of Maryland (College Park, Md.) en_US dc.contributor.department Physics en_US dc.subject.pqcontrolled Plasma physics en_US dc.subject.pqcontrolled Physics en_US dc.subject.pquncontrolled Magnetic Reconnection en_US dc.subject.pquncontrolled Magnetosphere en_US dc.subject.pquncontrolled MMS en_US
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