Contact discharges as a source of sub-nanosecond high voltage pulses

Judd, M.D. (2001) Contact discharges as a source of sub-nanosecond high voltage pulses. Journal of Physics D: Applied Physics, 34 (18). pp. 2883-2893. ISSN 1361-6463 (http://dx.doi.org/10.1088/0022-3727/34/18/323)

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Abstract

This paper describes a novel method for generating electrical transients. A small charged metal sphere coming into contact with the centre conductor of a coaxial transmission line is used to produce pulses with a risetime below 60 ps and amplitude of 500 V or more. The phenomenon is investigated experimentally to determine whether the gaseous medium in which the discharge takes place affects the pulse shape. Measurements in sulphur hexafluoride, argon and rough vacuum indicate that the breakdown mechanism is not a gas discharge, but the gas does affect the amplitude range, shape and variability of the current pulses. Results are interpreted in the light of previous investigations into arcs between electrodes separated by gaps of less than 100 µm, in which field emission of electrons from the cathode was recognized as the principal source of charge carriers. Potential applications for the contact discharge pulse generator are proposed and aspects of its operation that could be refined to reduce pulse shape variability are identified.