Events

Events at Physics

<< Fall 2022 Spring 2023 Summer 2023 >>
Subscribe your calendar or receive email announcements of events

Events on Monday, April 17th, 2023

Plasma Physics (Physics/ECE/NE 922) Seminar
Schnack Memorial Seminar: Simulating Transient Excitation of Neoclassical Tearing Modes
Time: 12:00 pm - 6:00 pm
Place: 2241 Chamberlin Hall
Speaker: Eric Howell, Tech-X Corporation
Abstract: Disruption avoidance and mitigation strategies are needed for ITER and future fusion pilot plants. Neoclassical tearing modes (NTMs) are a leading physics cause of disruptions in present-day experiments, and predictive NTM models are vital for the success of burning plasma tokamaks. NTM growth is driven by a helical bootstrap current deformation that results from pressure flattening across an island. NTMs are metastable states that require a seed island to grow. The seed islands are generated by ELMs, sawteeth, and other transients. Nonlinear simulations study the transient excitation of NTMs. Simulations use reconstructions of DIII-D ITER baseline scenario discharges. The dominant neoclassical effects, including the bootstrap current drive, are modeled using heuristic fluid closures for neoclassical stresses. Magnetic perturbations are transiently applied to excite a growing NTM. These perturbations act as surrogates for ELMs. A Goldilocks effect is observed with regard to the applied perturbation amplitude. If the amplitude is too small, no NTMs grow. If the amplitude is too large, a 2/1 NTM grows robustly immediately following the pulse. If the amplitude is just right, then the 2/1 NTM grows in two phases: an initial slowly growing phase followed by a fast robustly growing phase. An energy transfer analysis shows that the early slow growth phase is partially driven by nonlinear interactions with higher-n core modes. The later robust growth phase is described by the modified Rutherford equation.

The work is funded by the US Department of Energy
Add this event to your calendar
Department Meeting
Closed Department Meeting
Time: 12:15 pm - 1:30 pm
Place: VIRTUAL - link will be sent later.
Speaker: Mark Eriksson, UW-Madison
Closed meeting to discuss personnel matters—pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law Closed to all but tenured faculty
Host: Mark Eriksson
Add this event to your calendar