Event
MSE Seminar: Dr. Tim Koeth, UMD
Wednesday, September 23, 2026
3:30 p.m.
Room 2108 Chemical and Nuclear Engineering Building
Sherri Tatum
301-405-5240
statum12@umd.edu
Materials at the Extremes in the Classroom and the Lab
Abstract: In the classroom, we will briefly highlight the opportunities ENMA 427 provides MSE students to observe and measure how materials behave under extreme conditions through a series of unconventional, hands-on experiments. These include high-pressure exposure, hydrogen embrittlement, neutron imaging and irradiation, electromagnetic forming, and more. The presentation will focus on lightweight supersonic impact testing using a Mach 2 ping-pong ball cannon, demonstrating how an ordinary projectile can produce extraordinary material responses when accelerated to extreme velocities.
In the lab: Dielectric materials play an integral role in electronic communication, navigation, and defense systems that underpin modern life. Many of these applications require materials at the extremes, materials capable of maintaining functionality under intense radiation, high electric fields, and other demanding environments. Under these conditions, space charge accumulation and the resulting dielectric breakdown present persistent challenges to long-term reliability. Despite dielectric breakdown being a primary failure mechanism in these materials, the underlying dynamics of breakdown in bulk dielectrics remain poorly understood. A major obstacle is the extraordinary speed at which breakdown develops, making direct visualization exceptionally difficult.
To systematically investigate these dynamics, we developed a novel optical delay-line imaging system capable of imaging high-jitter, ultrafast dielectric breakdown events, along with two pulsed electroacoustic (PEA I and PEA II) systems capable of nondestructively mapping implanted charge-density profiles. Together, these complementary diagnostic techniques provide a direct view of the relationship between stored charge and the propagation dynamics of charge-induced dielectric breakdown and Lichtenberg figure formation in poly(methyl methacrylate) (PMMA). These observations reveal two distinct modes of electrical tree formation, including a previously unreported class of propagation. Most strikingly, this newly identified mode was observed to propagate at velocities exceeding ten million meters per second.
Over more than six years of investigation, this work has resolved several longstanding questions surrounding previously unexplained observations in charge-loaded dielectric breakdown and has provided new insight into the physical mechanisms governing electrical tree formation and propagation. Collectively, these measurements provide an unprecedented view of electrical breakdown dynamics in a bulk solid dielectric and, to our knowledge, capture the fastest propagation phenomenon yet directly optically imaged within a solid material.
Bio: Dr. Tim Koeth is an Assistant Professor, and a Clark Faculty Fellow, in the department of Materials Science and Engineering at the University of Maryland. He earned his PhD from Rutgers University in 2009 as a student in Fermilab’s Joint PhD Accelerator Physics Program under the direction of Helen Edwards. From 2013 to 2019, Dr. Koeth was the Director of the University of Maryland Nuclear Reactor & Radiation Facilities. Prof. Koeth’s current research investigates radiation damage studies on neutron detectors for CERN’s Large Hadron Collider, the Cryogenic Ultrahigh vacuum Radioactive Ion Experiment (CURIE) ion trap which studies electron capture nuclear decay rates, and what this presentation focuses on: high-energy electronic loading and associated damage of dielectrics in spacecraft. He is the Principal Investigator on several research contracts with DARPA, and Lockheed Martin. He holds affiliate appointments at Los Alamos National Laboratory and the National Institute for Standards and Technology. Prof. Koeth serves on the Board of the National Museum of Nuclear Science and History in Albuquerque, and has recently been invited to become an Emeritus Trustee.
