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Preliminary Exam
Magnetic Null Points Drifted by Magnetic Pressure and Tension Forces
Date: Thursday, September 17th
Time: 2:00 pm - 4:00 pm
Place: B343 Sterling
Speaker: Mary Yu, Physics PhD Graduate Student
Abstract: In configurations observed in natural systems, 3D magnetic null points often appear during magnetic reconnection. In the Terrestrial Reconnection Experiment (TREX) implemented in the Big Red Ball (BRB), magnetic reconnection is studied under controlled conditions in the collisionless regime. The applied configuration includes a cylindrically symmetric reconnection layer imploding onto the central axis of the experiment. The reconnection process ends as the reconnection layer reaches the center axis characterized by the formation of a double null-point configuration. This presentation will discuss how the two null points form, the rapid separation along the experimental z-axis, and the energy conversion due to field line shortening. A 16-tip Langmuir probe is used for collecting data of electron density, electron temperature, plasma potential, etc. High fidelity B-dot probes are used for collecting magnetic field data that resolve the dynamics at length scales much smaller than the ion skin-depth. The data has been processed to show the propagation of current layer of magnetic reconnection and magnetic nulls. The data shows ions are accelerated to the speed of magnetic null moving speed. Interesting features are found in data such as the electron heating at reconnection exhaust, two-fluid Hall effects yielding both quadrupolar and octopolar structures in the out-of-plane magnetic field.
Host: Jan Egedal
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