Some properties of a simple omegatron-type mass spectrometer

An experimental investigation is described, designed to show the effect of changing tube parameters on the resolution, sensitivity and resonant frequency for the N + 2 peak recorded by an omegatron-type mass spectrometer. Various departures from simple operation are reported, some of which are attributed to space charge, but it is shown that, under suitable operating conditions, the omegatron may readily be used for analysing simple mixtures of the lighter gases. For the apparatus described, the partial pressure detection limit at low total pressures is about 10 -11 mm of mercury.