Event
MSE Seminar: Dr. Tim Koeth, UMD
Wednesday, April 17, 2024
3:30 p.m.
Room 2110 Chemical and Nuclear Engineering Building
Sherri Tatum
301 405 5240
statum12@umd.edu
Materials at the Extremes: the Nature of Dielectric Breakdown in PMMA
Abstract: Dielectric components of electronic devices play an integral role in the communication, navigation, and defense systems 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 (i.e., satellites), space charging and resulting dielectric breakdown present a persistent and pressing challenge for long term functionality. However, 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 incredibly difficult to diagnose. In order to systematically study breakdown in dielectrics, a novel optical delay line apparatus was developed for use in imaging this high-jitter, extremely fast phenomenon. The resulting images obtained present the first-ever opportunity to undertake a detailed analysis of the propagation dynamics of dielectric breakdown in poly-methyl methacrylate. The result of this work included the identification of two distinct types of electrical tree formation, including a previously unreported classification. Significantly, the propagation of this novel electrical tree type was observed to exceed ten million meters per second and is believed to be the fastest physical phenomenon to ever be optically imaged in a solid material.
Following these novel observations, our group has been working to better understand and describe the mechanisms underpinning the observed discharge in these samples. This has included materials characterization of the poly-methyl methacrylate samples in an effort to identify charge trapping sites. Our group has also worked to understand sample charge retention times, measure the impact of temperature on the resulting discharge observed, and investigate this phenomenon in other dielectric materials. The results of this analysis, and the ongoing work surrounding the characterization of charge loaded dielectric materials will be presented.
Bio: Dr. Tim Koeth is an Assistant Professor at the University of Maryland's Department of Materials Science and Engineering.
