A Mass Spectrometer Type of Leak Detector

Abstract

An instrument is described which is capable of measuring one part of helium in 400,000 parts of other gases. The instrument is built around a 180° type mass spectrometer tube which is prefocused for helium ions. Use is made of this high sensitivity tube to locate leaks in vacuum equipment. The leaky container can be connected and evacuated by the pumps in the unit. A fine stream of helium played over the surface of the container will enter the leak and register immediately on the output meter. Very small leaks can be located easily to within a quarter of an inch. The unit is completely self‐contained, requiring only a line connection to a 110‐volt a.c. outlet.