Electrodynamic-tether time-domain reflectometer for analyzing tether faults and degradation

Abstract

We propose using time-domain-reflectometry (TDR) systems to locate and track faults along electrodynamic tether (EDT) systems. Inclusion of a TDR on long-duration EDT missions would facilitate tracking of the expected performance degradation due to faults caused by hazards such as micrometeors. The TDR technique has long been an effective tool for determining the location of loads and faults along common transmission lines (TLs) such as coaxial cables. Also sometimes known as pulse reflectometry, TDR works by sending an impulse down a TL and recording the reflected energy as a function of time. Measurement of the reflected TDR waveform provides insight into the physical structure of the TL and any loads, i.e., faults, along its length. In addition, the delay between launched and reflected signals determines the location of the load or fault. Hence, the TDR technique requires knowledge of the propagation characteristics of the TL under test. To examine the feasibility of extending the technique to EDTs we use a previously developed model for the tether transmission line. This model has temporal, and hence spatial, limitations, which may be overcome with enhancements to the tether TL model. We present some general parameters governing the development of such a tether TDR system as well as computer simulations of the TDR system’s response. © 2001 American Institute of Physics.