Speaker: Dr. Tim Koeth, Univ of Maryland
Title: Faster Than Fast - Plastic to Plasma in Nanoseconds. Investigating the high speed dynamics of novel dielectric tree formation
Abstract: Dielectric components play an integral role in the electronic communication, navigation, and defense systems and devices which underpin daily life in our modern world. For many of these devices, particularly those which are designed to operate in high-radiation environments like space, space charging and resulting dielectric breakdown present a persistent and pressing challenge for long term functionality. Despite constituting a primary cause of failure for these materials, the dynamics of dielectric breakdown in bulk dielectric materials are not well understood. This is due in large part to the immense speeds at which these events occur, making it difficult to visualize. In order to systematically study dielectric breakdown in dielectrics, a novel optical delay line apparatus was developed for use in imaging this high-jitter, extremely fast phenomena. The resulting images present the first-ever opportunity to undertake a detailed analysis of the propagation dynamics of the dielectric breakdown in poly-methyl methacrylate. The result of this work includes the identification of two distinct types of electrical tree formation, including a previously unreported classification. More significantly, the propagation of this novel electrical tree type was observed to exceed 10 mil meters/sec and is believed to be the fastest physical phenomenon to ever be optically imaged in a solid material. The results of this analysis and the ongoing work surrounding the characterization of charge loaded dielectric materials will be presented.
Bio: Dr. Koeth is an Assistant Professor of Materials Science & 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. His 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 PI 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. He serves on the Board of the National Museum of Nuclear Science and History.
Equally passionate are his personal research pursuits; Dr. Koeth is actively engaged in the collection and preservation of early atomic age artifacts, vintage cryptologic machines, and classic (atomic era) Tektronix oscilloscopes. His historical work has appeared on the cover of Physics Today (May 2019) and featured in interviews on NPR’s Morning Edition (August 2019). Recently, one of his artifacts has been made the centerpiece for a new exhibit, The Dark Cube, at the National Museum of Nuclear Science and History, located in Albuquerque, New Mexico. Research group website: https://koethgroup.umd.edu/