A sensitive, constant resistance pirani gauge with a fast response time

Abstract

A sensitive Pirani-type gauge with good zero stability and a fast response time is described. A 10 micron diameter tungsten wire is maintained at a constant resistance by a feed-back circuit. The instrument will detect pressure changes of 6 × 10 −6 torr at pressures up to 10 −2 torr and 4 × 10 −5 torr at 10 −1 torr, zero drift is less than 10 −5 torr over periods up to 6 hours and the time constant for response to pressure changes varies from 0.14 sec at 10 −6 torr to 0.02 sec at 10 −1 torr.