Seminars

Abstract: Partially ionized gases enable technological advances in a wide range of disciplines. However, the fundamental physics remains complex due to the nonlinear interactions of various physical and chemical processes, including electromagnetic fields, instabilities, oscillations and turbulence, collisions and reactions, and plasma-immersed materials. The multiscale nature of the low temperature plasmas ranging from small-scale turbulent features to large-scale self-organizing structures poses significant challenges in modeling such nonlinear dynamics. It is therefore critical to develop various numerical capabilities accounting for the hierarchy of governing equations and the associated assumptions. 

In this talk, I will present the development of theoretical and computational models of low-temperature magnetized plasmas in Hall effect thrusters. One class of computational models is physics-based models, such as fluid, particle-based kinetic, and grid-based direct kinetic (DK) methods. I will discuss the fluid and kinetic instabilities that lead to anomalous electron transport and self-organization as well as the development of a new type of plasma fluid model, which we call the full fluid moment (FFM) model. Another type of modeling is physics-informed data-driven techniques that utilize experimental data to infer the unobserved variables. I will focus on discussing the development of state estimation techniques for plasma dynamics.   

Biography: Ken Hara is an Assistant Professor of Aeronautics and Astronautics at Stanford University. He received a Ph.D. in Aerospace Engineering and a Graduate Certificate in Plasma Science and Engineering from the University of Michigan, and B.S. and M.S. in Aeronautics and Astronautics from the University of Tokyo. He was a Visiting Research Physicist at Princeton Plasma Physics Laboratory as a Japan Society for the Promotion of Science Postdoctoral Fellow. Prior to joining Stanford University, he was a tenure-track Assistant Professor in Aerospace Engineering at Texas A&M University. His research interests include electric propulsion, low temperature plasmas, plasma physics (plasma-wall interactions, plasma-wave interactions), data-driven modeling, rarefied gas flows, and computational fluid and plasma dynamics. He is a recipient of the Air Force Young Investigator Program Award, the Department of Energy Early Career Award, and the Office of Naval Research Young Investigator Program Award.