Plasma Physics (Physics/ECE/NE 922) Seminars |
Events During the Week of February 19th through February 26th, 2023
Monday, February 20th, 2023
- Into the Nonthermal Landscape: Searching for a Statistical Mechanics for Turbulent Particle Acceleration in Collisionless Plasmas
- Time: 12:00 pm
- Place: 2241 Chamberlin Hall
- Speaker: Vladimir Zhdankin, Center for Computational Astrophysics, Flatiron Institute
- Abstract: Turbulence has long been considered as a candidate process for accelerating particles to relativistic energies in collisionless space and astrophysical plasmas. Particle-in-cell (PIC) simulations of relativistic (and trans-relativistic) turbulence have recently opened this topic to rigorous, first-principles numerical scrutiny. I will describe progress on understanding nonthermal particle energization by turbulence, focusing on the relativistic regime. PIC simulations demonstrate efficient turbulent particle acceleration and confirm its diffusive nature, while also yielding new insights into the electron-to-ion heating ratio and radiative signatures. However, the prevalence and properties of power-law particle energy distributions remains a mystery. I suggest that a complete understanding will require us to confront the age-old problem of anomalous entropy production in collisionless plasmas. I will describe recent theoretical efforts to model particle acceleration with generalized maximum entropy principles, which can explain several surprising numerical results and may extend to phenomena beyond turbulence (such as magnetic reconnection). The next several years promise to bring fundamental breakthroughs into these problems.
Tuesday, February 21st, 2023
- No events scheduled
Wednesday, February 22nd, 2023
- No events scheduled
Thursday, February 23rd, 2023
- Breaking Barriers in Magnetic Confinement Fusion Using Direct Construction Methods
- Time: 2:30 pm
- Place: B343 Sterling Hall
- Speaker: Rogério Jorge, Instituto Superior Tecnico, Portugal
- Abstract: The pursuit of magnetic confinement fusion demands the implementation of magnetic fields with exceptional properties to maintain high-temperature plasmas, regulate plasma density, fast particle dynamics, and turbulence. In traditional design methods for stellarator machines, magnetic fields and coils were optimized independently, leading to stringent engineering tolerances and a neglect of the impact of turbulence on confinement. Recent advancements in the optimization of stellarator devices, however, have made significant contributions to the field. These innovations include direct near-axis designs, integrated plasma-coil algorithms, and precise quasisymmetric and quasi-isodynamic fields, as well as direct turbulence optimization. These approaches allow for a more comprehensive and efficient optimization process, taking into account the interdependence of magnetic fields and plasma parameters. This presentation will delve into the details of these innovations in magnetic confinement fusion optimization algorithms and their implications for the advancement of fusion devices in plasma physics.
Friday, February 24th, 2023
- No events scheduled