Events at Physics |
Events During the Week of March 24th through March 31st, 2024
Sunday, March 24th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
Monday, March 25th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
- Department Meeting
- Closed Department Meeting
- Time: 12:15 pm - 1:15 pm
- Place: B343 Sterling Hall
- Speaker: Mark Eriksson , UW - Madison
- Closed meeting to discuss personnel matters—pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law
- Host: Mark Eriksson
- Thesis Defense
- A CHAPMAN-ENSKOG-LIKE (CEL) CONTINUUM KINETIC CLOSURE APPROACH IN NIMROD
- Time: 1:00 pm
- Place: B343 Sterling
- Speaker: Joseph Jepson, Physics Graduate Student
- Abstract: Herein, a numerical method for solving a Chapman-Enskog-like (CEL) continuum kinetic model for plasmas is formulated, analyzed, and applied in the plasma fluid code NIMROD. The CEL approach is a $\delta f$ drift kinetic approach that allows rigorous closure of the plasma fluid equations in all collisionality regimes. Importantly, in this approach, the zeroth-order in $\delta$ ($\delta\equiv\rho_i/L$, with $\rho_i$ the ion gyroradius and $L$ a macroscopic length scale) distribution function is a time-evolving Maxwellian. This difference leads to an $O(\delta)$ kinetic equation that analytically enforces that the first-order kinetic distortion $f_1$ have no number density ($n$), flow ($\mathbf{u}$), and temperature ($T$) moments. The fluid variables in this method are allowed to deviate far from an initial equilibrium. The fluid equations are closed by incorporating appropriate velocity space moments of the first-order kinetic distortion.
An axisymmetric poloidal flow damping calculation is performed to benchmark the implementation. It is first shown that the kinetic aspects of the implementation give results for the steady-state poloidal flow that agree both with other codes, analytics, and a fixed-background (i.e. $f_0$ a stationary Maxwellian) $\delta f$ implementation in NIMROD. It is then shown that the flow dynamics in the full CEL approach agree well both with analytics, and with results from the fixed-background $\delta f$ implementation.
A von Neumann linear stability analysis of the full fluid-kinetic system is also performed to help elucidate methods to make the time advance of the full system numerically stable. It is shown that numerical stability is impossible to achieve without explicitly enforcing key tenets of the CEL closure approach, in particular, that the $n$, $\mathbf{u}$, and $T$ moments of the kinetic distortion remain small in time. In addition, it is shown that centering the heat flux at the beginning of the time step and the ion temperature at the end of the time step in the kinetic equation allows for a numerically-stable time advance of the coupled fluid-kinetic system. Furthermore, these linear stability results are seen to remain applicable when running NIMROD fully nonlinearly.
The methodology of applying the CEL approach to non-axisymmetric problems is also discussed. Future work will include applying this closure approach to the problem of forced magnetic reconnection in toroidal geometry, as well as to accurate simulation of neoclassical tearing modes (NTMs) in tokamaks. - Host: Chris Hegna
- Graduate Program Event
- How to Prelim
- Time: 2:00 pm - 2:30 pm
- Place: 5310 CH
- Abstract: If you plan to complete your prelims in the next 6 months, join this session to learn about the process.
- Host: Sharon Kahn
Tuesday, March 26th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
- Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
- The present and future of flavor in high-energy cosmic neutrinos
- Time: 2:00 pm - 3:00 pm
- Place: Join Zoom Meeting Meeting ID: 912 3071 4547
- Speaker: Mauricio Bustamante , NBIA, Denmark
- Abstract: The flavor composition of high-energy cosmic neutrinos, i.e., the proportion of neutrinos of different flavor in their flux---electron, muon, and tau---is a versatile observable to test astrophysics and particle physics. For astrophysics, it allows us to identify the neutrino production process and so narrow down the identity of their sources. For fundamental physics, it allows us to probe physics beyond the Standard Model at hitherto untested energies. Yet, so far, the experimental difficulties involved in measuring flavor composition in IceCube have hampered its physics reach. Fortunately, this may be for not much longer, thanks to upcoming, larger neutrino telescopes. I will show state-of-the-art forecasts for the measurement of the flavor composition of TeV-PeV cosmic neutrinos in the next two decades using the combined detection by multiple neutrino telescopes. Together, they could enable measurements of the energy dependence of the flavor composition---revealing changes in the neutrino production process---and of its directional dependence---revealing flavor asymmetries in the high-energy neutrino sky. I will conclude by proposing novel techniques to extend flavor-composition measurements to ultra-high energies, beyond 100 PeV, using large-scale neutrino radio-detection in IceCube-Gen2 and GRAND.
Topic: N3AS online seminar series - Spring 2024 #6
Time: Mar 26, 2023 2:00 PM
NOTE: All participants and hosts are now required to sign into a Zoom account prior to joining meetings hosted by UC Berkeley.
- Host: A. Baha Balantekin
Wednesday, March 27th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
- ALMA Community Day Event
- ALMA Proposal Preparation Workshop
- Time: 9:00 am - 4:00 pm
- Place: B343, Sterling Hall
- Speaker: Stephen McKay, UW-Madison
- Abstract: The National Radio Astronomy Observatory (NRAO) and ALMA Ambassadors invite you to an ALMA Proposal Workshop at the University of Wisconsin-Madison. This event is designed for all astronomers, and in particular for those who do not regularly utilize radio / millimeter data in their research. The one-day (virtual and in-person) workshop will provide an overview of ALMA including new capabilities for Cycle 11, a brief discussion of millimeter interferometry, and an overview of the proposal preparation and submission processes. In addition, there will be a hands-on session to prepare proposals for the upcoming ALMA Cycle 11 deadline (April 25th).
Registration for the workshop is free for all participants, and lunch will be provided for in-person participants. Please sign up by March 20th in order to provide an accurate count for lunches and so the workshop content can be tailored to suit your needs.
Registration and more info: - Host: Stephen McKay
- Department Meeting
- Closed Department Meeting
- Time: 12:15 pm - 1:15 pm
- Place: B343 Sterling Hall
- Speaker: Mark Eriksson , UW - Madison
- Closed meeting to discuss personnel matters—pursuant to Section 19.85(1)(c) of the Wisconsin Open Meetings Law
- Host: Mark Eriksson
- Graduate Program Event
- How to finish your PhD
- Time: 1:00 pm - 1:30 pm
- Place: 5310 CH
- Abstract: If you plan to complete your PhD in the next 6-9 months, join this session to learn about the process.
- Host: Sharon Kahn
Thursday, March 28th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
- Spring Break Potluck Lunch
- Time: 11:30 am - 1:00 pm
- Place: 5280 Chamberlin
- Abstract: Bring something yummy to share and join us for a potluck lunch! Last year, we managed to land on Pi Day – not so lucky this year, so it’ll be a post-Pi Day lunch (just trying to give us an excuse to share pie!).
What to bring: Bring a dish to share – and let’s celebrate the diversity of cultures and backgrounds in our department – we encourage you to bring something yummy from your culture. Pies welcome, even thought it’ll be after Pi Day!
Who: Any and all Physics folks (grads, faculty, staff, postdocs, undergrads)
The department will provide plates and eating utensils. We also have a variety of serving spoons/tongs, if needed.
The department will also provide soda and sparkling water.
- Host: Sharon Kahn
Friday, March 29th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
Saturday, March 30th, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*
Sunday, March 31st, 2024
- Academic Calendar
- Spring recess
- Abstract: *Note: actual end time may vary.*