Study of Electrical Contact Under AC and Nonlinear Conditions
Abstract
This Final Technical Report covers a 4-year performance period (2/15/2018 - 2/14/2022). The research activities changed midway because of the outbreak of the Covid-19 pandemic. Significant, impactful results were obtained throughout. 1. The contact resistance under AC condition was calculated for the first time, between two current channels of unequal dimensions, made with dissimilar materials. Scaling laws for the AC contact resistance were constructed. The immensely important but difficult technical problem of electromagnetic fields at a triple point is given a partial solution. Also discovered is negative AC contact resistance, meaning that the AC total resistance in the two current channels,under certain conditions, is less than the sum of the AC bulk resistance in the individual current channels. 2.The steady state temperature distribution, including nonlinear temperature dependence in the thermal conductivity and in the electrical resistivity, has been applied to looped carbon nanotubes, and successfully compared with experimental data obtained from Air Force Research Laboratory at Wright-Patterson AFB. 3. The classical Ramo-Shockley (RS) theorem, which gives the induced current on conductors due to motion of nearby charges under the assumption quasi-static fields, is extended to include relativistic and radiative effects, for the first time. Exact, simple closed form solutions are constructed in idealized models, which were validated by very different numerical schemes. In addition to the features that were absent in the classical RS, such as electromagnetic transients and reflections of electromagnetic waves, we discovered the generation of an electromagnetic shock when a charge strikes a conductor and is subsequently removed. We found that this shock-induced current is unimportant (compared with the classical RS induced current) at low electron impact energies, such as 100s eV. The shock-induced current becomes important when the electron impact energies.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 21, 2022
- Accession Number
- AD1230671
Entities
People
- Y. Y. Lau
Organizations
- Board of Regents of the University of Michigan