Response of Helical Structures to High Speed Pulses or When Can a Helix Be Called an Inductor
LAWRENCE LIVERMORE NATIONAL LAB CA
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Vacuum and dielectric cored loosely wound helices are widely used in pulse power systems. In one extreme, when the applied pulse length is shorter then the transit time in the helix, helices are used as transit time isolators, to lead signals from high voltage terminals to ground 1. In the other extreme, for pulse durations that are much longer than the transit time, helices act as conventional inductors and are used for high frequency isolation or as shields for trigger, signal or gas leads to pulse power components. In either case, the use of helices in the presence of fast pulses requires an understanding of their behavior in regimes where time delays associated with wave propagation in the helix are not negligible when compared to the length or risetime of the applied pulse and hence their description as lumped elements is no longer correct. This paper describes the results of analytical approximations, circuit simulations, 3-D time dependent electromagnetic modeling as well as laboratory measurements on helices surrounded by conducting structures. On the basis of these investigations their suitability as voltage measuring devices will be discussed.
- Electrical and Electronic Equipment
- Theoretical Mathematics