Graduate Program Events |
Events During the Week of December 3rd through December 10th, 2023
Monday, December 4th, 2023
- No events scheduled
Tuesday, December 5th, 2023
- No events scheduled
Wednesday, December 6th, 2023
- Towards Measurement of Pressure Anisotropy during Collisionless Magnetic Reconnection
- Time: 2:30 pm - 6:00 pm
- Place: B343 Sterling or
- Speaker: Cameron Kuchta, Physics PhD Graduate Student
- Abstract: The Terrestrial Reconnection EXperiment (TREX) at the Wisconsin Plasma Physics Laboratory (WiPPL) studies collisionless magnetic reconnection [1]. We have developed a new Pressure Anisotropy (PA) probe consisting of 24 langmuir probes; 12 outer tips collect plasma isotropically while the remaining 12 inner tips are shielded and receive plasma directionally. This allows us to measure plasma flows and pressure anisotropy during reconnection. With recent upgrades to our experiment, we are now able to enter the collisionless kinetic regime of magnetic reconnection in which we expect electron anisotropy effects to dominate the physics in the ion diffusion region. This regime is relevant to reconnection in the magnetosphere. Embedded jets, seen in laboratory data, are driven into the outflow of reconnection as expected from spacecraft observation, theory, and simulations [2]. We have also observed signatures of pressure anisotropy with the PA probe. Current progress on probe design and analysis will be presented.
[1] Olson et al. PRL (2016) 116, 255001.Experimental Demonstration of the Collisionless Plasmoid Instability below the Ion Kinetic Scale during Magnetic Reconnection [2] Wetherton et al. JGR Space Physics (2021) 125, e2020JA028604. doi.org/10.1029/2020JA028604
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-SC0018266 and DE-SC0020989. It is also based upon work supported by NASA under award No. 80NSSC22K0556. - Host: Jan Egedal
Thursday, December 7th, 2023
- No events scheduled
Friday, December 8th, 2023
- Preliminary Exam
- Detection and Characterization of Core Magnetic Fluctuations on DIII-D using Faraday-Effect Polarimetry
- Time: 1:30 pm - 3:30 pm
- Place: 2301 Sterling
- Speaker: Rachel Myers, Department of Physics Graduate Student
- Abstract: Internal, resistive MHD instabilities called tearing modes (TMs) significantly contribute to disruptions and confinement degradation in tokamaks. Measuring nonlinear TM coupling with high m/n near the magnetic axis can aid in understanding neoclassical TM seeding, growth, and decay. For this tracking, we use the Radial Interferometer-Polarimeter (RIP), which is sensitive to core-resonant magnetic fluctuations on DIII-D and has detected TMs well before they appear on edge magnetic sensing coils [Pandya, DPP invited talk 2021]. Here we employ RIP to analyze the impact on pre-existing TMs of multiple, emerging MHD modes that are never detected by the coils. In one example, RIP detects a higher-frequency mode coupled to both an n=2 mode and a lower-frequency mode that later diminishes. All three modes are resonant near the magnetic axis, and their interaction is only visible using RIP. In this talk we will also discuss tearing mode structure and its potential effects on RIP-measured tearing mode amplitudes.
Zoom link: - Q&A with ISS representative
- Time: 2:15 pm - 3:00 pm
- Place: 2241 Chamberlin
- Abstract: Sara Sheibani from ISS will be joining us. She will have a short presentation about ISS and then we’ll have plenty of time for questions. I encourage you to pose questions in advance, but feel free to just bring them along, too. Questions ahead can be added here: Hope to see you there! p.s. Come to ask questions. . .or come for the bagels and coffee! Either way, come join us!
- Host: Sharon Kahn and Arifa