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Events on Thursday, February 15th, 2024

Academic Calendar
Spring recess
Abstract: *Note: actual end time may vary.*
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Plasma Seminar
Stellarators Linking Axisymmetric Mirrors (SLAM)
Time: 1:00 pm - 2:00 pm
Place: B343 Sterling Hall
Speaker: Tony Qian, Princeton Universtiy
Abstract: This talk motivates the study of using optimized stellarators to link large volume axisymmetric mirrors for the purpose of fusion energy. There are significant challenges in scaling optimized stellarators to fusion reactors, in particular the construction of a large volume 3D device which has a breeding blanket integrated with complex geometry. Meanwhile, mirrors have large volume and simple coils, but face plasma physics issues due to open field line end loss, velocity space anisotropy, MHD stability, and turbulence (once confinement allows sufficiently high temperature gradients). We propose a hybrid approach that overcomes challenges of each, enabled by modern stellarator optimization. It consists of axisymmetric mirror cells linked by stellarator segments. Most of the plasma volume is in the mirror cells, where the typical loss cone is replaced by a source cone from the stellarator. The goal is to combine the simple engineering of axisymmetric, linear mirror cells with the good plasma confinement and stability of stellarators. Two questions arise: do such flux surfaces exist? If so, are they MHD stable? We discuss a basic plasma physics experiment that can be built to address these questions using the unique capabilities at UW-Madison.
Host: Jan Egedal
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Theory Seminar (High Energy/Cosmology)
Tabletop to Telescope: Unraveling the Mystery of Dark Matter
Time: 4:00 pm - 5:00 pm
Place: 5280 Chamberlin Hall
Speaker: Tanner Trickle, Fermilab
Abstract: Recent years have seen a dramatic expansion in ideas to search for dark matter beyond the WIMP paradigm. In this talk we'll discuss a diverse range of new approaches, starting with small-scale tabletop experiments. These experiments target dark matter particles far lighter than WIMPs using innovative ideas from condensed matter physics and quantum sensing. New calculations have transformed our understanding of how dark matter can interact with electrons and are essential for current experimental efforts. Additionally, we'll explore how collective excitations, e.g., phonons and magnons, can revolutionize the way we search for dark matter. Complementing these tabletop experiments, pulsar timing arrays are exceptionally sensitive to new physics on galactic scales. While their primary purpose is to detect stochastic gravitational wave backgrounds, we'll show how their extraordinary precision can be leveraged to hunt for both the lightest, and heaviest, dark matter candidates.
Host: Lisa Everett
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