Scientists & Staff

Benedikt Geiger started his career at UW-Madison in February 2019 and has become the Principle Investigator of the HSX stellarator experiment June 2023. His research interests are the experimental investigation of turbulent particle and heat transport with the aim to develop new turbulence-optimized stellarator experiments. He teaches in the field of nuclear engineering and plasma physics.

Alexis (Briesemeister) Wolfmeister re-joined the HSX team as a part-time scientist in October of 2023 after an extended break focused on parenting. She oversees the HSX diagnostics with a particular focus on visible spectroscopy. Alexis previously worked as a researcher for ORNL at the DIII-D tokamak. In 2013 she completed her PhD at HSX on intrinsic flow measurements.

Benjamin holds a PhD in Physics for the University of Wisconsin-Madison and is an expert on turbulence in stellarator devices. A computational physicist by training, he currently holds a staff scientist position in the Department of Engineering Physics at UW-Madison working on building new tools and infrastructure for stellarator optimization, with a focus on turbulent optimization.

Xiang Han joined UW Madison as a scientist in March 2022 and began working on HSX in 2023. He focuses on the development of diagnostics with microwave (reflectometry, ECE, etc.) and spectroscopic technologies, as well as on the experimental research on turbulence and transport at the interface between open and closed field-line regions on both HSX and W7-X stellarators. Xiang Han previously worked as a postdoc at Forschungszentrum Jülich (Germany) and as a scientist at EAST tokamak (ASIPP, China).

Dieter Boeyaert joined the HSX team as a scientist in October 2023. He focusses on designing a resilient divertor for HSX using field-line tracing (FLARE) and advanced plasma edge codes (EMC3-EIRENE), and on studying the plasma edge by comparing simulations with experimental data. Dieter joined the UW-Madison as a postdoc in 2021 working on EMC3-EIRENE modeling of the W7-X stellarator after obtaining a PhD from the KU Leuven (Belgium) in collaboration with the Forschungszentrum Jülich (Germany) about SOLPS-ITER simulations of the EAST tokamak.

Wayne completed his PhD and joined HSX as a postdoctoral researcher in 2024. His research is focused on the development of RF and optical diagnostics.

Ben Knowles received his MS in Astrophysics from the University of Colorado at Boulder in 2001, and was the ISS Calibration Engineer for the Cassini Mission during its tour of Saturn. He has also worked in private industry as a Software and Controls Engineer, focusing on automation and scientific instrumentation. He moved to the HSX team in August of 2021, where he develops and maintains the HSX computer and data acquisition network.

Rex comes to HSX with 20+ years of engineering experience in aerospace, automotive, and nuclear industries.

Chris joined UW Madison in 2021 as an instrumentation engineer and is our expert for the HSX vacuum system, high voltage power supplies and the design of low noise amplifiers.

George joined the HSX lab in 2023 as an mechanical instrumentation technologist. Since then, he has been instrumental in preparing the HSX stellarator experiment for plasma operation.

David Anderson is the former PI of HSX and has been associated with the experiment since its initial design activities in 1990. Today, he is a Co-Principal Investigator of HSX with strong ties to the experimental program and it’s scientific mission.