530 / 2017-05-11 22:42:42

A measurement of intrinsic outgassing rates in vacuum interrupters

Vacuum interrupters, Magnetron vacuum measurement, outgassing, leak rate,lifetime

In our paper The effect of magnetron discharge pressure measurement on the actual pressure in vacuum interrupters (ICEPE TS 2015) it was reported that in 2013 the vacuum pressures in a batch of old (more than 30 years) vacuum interrupters had been were measured with a magnetron apparatus before putting them into storage. These interrupters would have had pressure in the 10-6 mbar range when new, and after more than 30 years ther their pressures were found to be in the 10¬-5 mbar range. This is typical for interrupters of that age. Two years later, in 2015, the pressures were measured again, and it was found that the pressures were now much lower, in the 10-6 or 10-7 mbar ranges. It was proposed that the extended electrical discharges involved in the 2013 measurements had the effect of removing gas from the system to extremely low levels, and that the pressures seen in 2015 arose from outgassing of each interrupter in the batch. In the 2015 measurements the discharges were extended for even longer, to try to reset the pressures even lower. Since then the magnetron apparatus has been improved to measure low pressures better and the measurements we will now report in 2017 will be an attempt to measure the intrinsic outgassing rates reasonably accurately and to prove that intrinsic outgassing occurs in vacuum interrupters.