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Events on Friday, May 12th, 2023

Graduate Program Event
PhD Final Defense
Pressure-driven tearing and energy transport in finite beta Reversed Field Pinch computations
Time: 10:00 am - 12:00 pm
Speaker: Urvashi Gupta, Department of Physics Graduate Student
Abstract: Pressure-driven effects on magnetic relaxation dynamics and energy transport of an inductively-driven Reversed-Field Pinch device are investigated in a 3D cylindrical magnetohydrodynamics model. Pressure-driven dynamics in RFPs are often assumed to be small. However, unfavorable average curvature in RFPs means that pressure does influence tearing and consequently transport along stochastic field lines. In this work, nonlinear NIMROD computations are applied to model the RFP at experimentally relevant plasma-$\beta$ values. Self-consistent evolution of fluctuations from an Ohmic steady state that includes thermal conduction and heating results in tearing dominant relaxed states with sustained reversal. Linear computations are applied to profiles extracted from the relaxed nonlinear state to study the sources of free energy for the fluctuations. The parallel current drive and pressure-curvature drive for the obtained linear eigenfunctions are found to be comparable and only the sum of both the terms surpasses the stabilizing contribution to drive tearing modes. Energy transport via fluctuation-induced conduction and convection is computed for the nonlinear relaxed states and qualitative agreement with recent experimental results is observed. The heat flux densities are further decomposed to assess the significance of different orders of correlations. The implications of artificial particle diffusion on convective transport and the overall relaxed state are also discussed for this self-consistent MHD model.
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Probing The Impact of Cluster Weak Lensing Bias On DES Y1 Cluster Cosmological Results
Time: 12:00 pm - 1:00 pm
Place: Chamberlin 5280
Speaker: Johnny Esteves, University of Michigan
Abstract: Over the last two decades of large photometric surveys, optical cluster cosmology has presented a promising way to improve cosmological measurements and our current understanding of dark matter and dark energy. The Dark Energy Survey (DES) Y1 cluster's analysis has revealed a new systematic effect that affects weak lensing measurements, called weak lensing bias. The weak lensing bias arises from the correlation between the mass proxy (such as richness or λ) and the lensing profile for a given mass. The effect is mainly caused by the presence of projected red galaxies along the line of sight, which can bias the mass estimate. However, how this systematic effect impacted the Y1 cosmology is still unclear.

In this talk, I will present a novel forward modeling methodology that was developed specifically for Y3 and outline the technical computing challenges involved in solving multi-dimensional integrals. These challenges have been overcome by utilizing graphics processing units (GPUs), which provide exceptional computational speed and accuracy. In addition, I will present my work on the commissioning of the Rubin Observatory, which will provide invaluable data for advancing our cosmological understanding of the Universe.
Host: Keith Bechtol
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Graduation Event
Graduate Celebration Event
Time: 3:00 pm - 5:15 pm
Place: 2241 Chamberlin Hall
Speaker: Sharon Kahn and Evan Heintz
Abstract: Come celebrate and congratulate our 2023 graduates from both the undergraduate and Ph.D. Programs! We will celebrate the Ph.D. graduates from 3:00 - 3:30, enjoy treats and ice cream from 3:30 - 4:00, and then celebrate the undergraduates from 4:00 - 5:15.
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Academic Calendar
Graduate School Spring 2023: Master&#39;s degree deadline
Time: 4:00 pm - 5:00 pm
Abstract: Degree candidates must complete all steps: CONTACT: 262-2433,
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