Thesis Defense |
Events on Tuesday, November 11th, 2025
- Instability Saturation and Turbulent Dynamos in Shear Flows
- Time: 9:00 am - 11:00 am
- Place: B343 Sterling Hall
- Speaker: Bindesh Tripathi
- Abstract: Instabilities in nature drive turbulence, which impedes fusion-energy gain in reactors and impacts cosmic observables such as magnetic fields and multi-messenger-astronomy signals. To understand the underlying turbulent processes, this thesis investigates two central questions: How instabilities may saturate, and how turbulence may generate astrophysical magnetic fields at large scales—a process called the dynamo. Previous efforts to address the former have relied exclusively on an energy cascade to microphysical scales and thus missed critical elements of instability-scale mode-couplings. Dynamo efforts have been frustrated because large-scale magnetic-field generation is suppressed via Alfvénization—a robust magnetohydrodynamic process that aligns fluctuations in the fluid velocity u with those in the magnetic field b, i.e., u||b. Addressing these challenges, this thesis develops fundamental principles of instability saturation and applies them to demonstrate a novel mechanism where Alfvénization generates magnetic fields, instead of suppressing the fields. These findings, organized in three parts, apply to shear flows driven unstable by their velocity gradients.
- Host: Paul Terry