Abstract
We have conducted a series of experiments designed to measure the flashover strength of various azimuthally symmetric 45° vacuum-insulator configurations. The principal objective of the experiments was to identify a configuration with a flashover strength greater than that of the standard design, which consists of a 45° polymethyl-methacrylate (PMMA) insulator between flat electrodes. The thickness d and circumference C of the insulators tested were held constant at 4.318 and 95.74 cm, respectively. The peak voltage applied to the insulators ranged from 0.8 to 2.2 MV. The rise time of the voltage pulse was 40–60 ns; the effective pulse width [as defined in Phys. Rev. ST Accel. Beams 7, 070401 (2004)] was on the order of 10 ns. Experiments conducted with flat aluminum electrodes demonstrate that the flashover strength of a crosslinked polystyrene (Rexolite) insulator is (18±7)% higher than that of PMMA. Experiments conducted with a Rexolite insulator and an anode plug, i.e., an extension of the anode into the insulator, demonstrate that a plug can increase the flashover strength by an additional (44±11)%. The results are consistent with the Anderson model of anode-initiated flashover, and confirm previous measurements. It appears that a Rexolite insulator with an anode plug can, in principle, increase the peak electromagnetic power that can be transmitted across a vacuum interface by a factor of [(1.18)(1.44)]2=2.9 over that which can be achieved with the standard design.7 MoreReceived 26 November 2004DOI:https://doi.org/10.1103/PhysRevSTAB.8.050401This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Highlights
Experiments conducted on pulsed-power and particle accelerators typically require that a high-voltage pulse be transmitted across a vacuum-insulator interface
Since 1964, the standard interface for pulsed applications has consisted of a 45 polymethyl-methacrylate (PMMA) insulator between flat electrodes, or several such systems connected in series [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. (A cylindrical configuration of several insulators in series is often referred to as an insulator stack [1,14 –17,32,36 – 44].) Because of various technical considerations, it is usually desired to minimize the distance at the interface over which the voltage is applied; it is of interest to develop an interface with a flashover strength greater than that of the standard design
The results obtained by Milton [5,7] and Roth and coworkers [33] suggest that the flashover of a 45 insulator is not likely to initiate at the cathode triple junction, since if this were the case, the flashover strength would increase as " is increased
Summary
Experiments conducted on pulsed-power and particle accelerators typically require that a high-voltage pulse be transmitted across a vacuum-insulator interface. Since 1964, the standard interface for pulsed applications has consisted of a 45 polymethyl-methacrylate (PMMA) insulator between flat electrodes, or several such systems connected in series [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. Since 1964, the standard interface for pulsed applications has consisted of a 45 polymethyl-methacrylate (PMMA) insulator between flat electrodes, or several such systems connected in series [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36]. (A cylindrical configuration of several insulators in series is often referred to as an insulator stack [1,14 –17,32,36 – 44].) Because of various technical considerations, it is usually desired to minimize the distance at the interface over which the voltage is applied; it is of interest to develop an interface with a flashover strength greater than that of the standard design
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