Publications

Abstract not provided.

This work developed a methodology for transmission line modeling of cable installations to predict the propagation of conducted high altitude electromagnetic pulses in a substation or generating plant. The methodology was applied to a termination cabinet example that was modeled with SPICE transmission line elements with information from electromagnetic field modeling and with validation using experimental data. The experimental results showed reasonable agreement to the modeled propagating pulse and can be applied to other installation structures in the future.

This report summarizes research performed in the context of a REHEDS LDRD project that explores methods for measuring electrical properties of vessel joints. These properties, which include contact points and associated contact resistance, are “hidden” in the sense that they are not apparent from a computer-assisted design (CAD) description or visual inspection. As is demonstrated herein, the impact of this project is the development of electromagnetic near-field scanning capabilities that allow weapon cavity joints to be characterized with high spatial and/or temporal resolution. Such scans provide insight on the hidden electrical properties of the joint, allowing more detailed and accurate models of joints to be developed, and ultimately providing higher fidelity shielding effectiveness (SE) predictions. The capability to perform high-resolution temporal scanning of joints under vibration is also explored, using a multitone probing concept, allowing time-varying properties of joints to be characterized and the associated modulation to SE to be quantified.

Abstract not provided.

The possibility of estimating the effective resistance at contact points along a seam in a cylindrical vessel is investigated. The vessel is formed from two top-hat structures bolted together at a flange. Aluminum shims at the bolt locations ensure a nearly constant 5-mil gap or slot between the flanges. Cavity modes are excited with a short monopole antenna inside the structure, and external near fields 5 mm away from the slot are probed around the vessel circumference. Comparison of CST and FDTD simulations with measurements reveals that the shape of the field-vs-angle curve is strongly dependent on the contact resistance, indicating that meaningful estimates can be extracted.