Calculation and measurements on the characteristics of ion production in a high vacuum cylindrical magnetron were performed. The coincidence between measured and calculated results is fairy good. The magnetron type ionization gauge offers a good stability owing to the space-charge saturation effect. The experimental results indicate a different characteristic from that obtained by Conn and Daglish. In our results, the secondary electrons which are produced accompanying with the gas ionization exhibit a marked effect. It may be considered that this effect is related to the Philips gauge type discharge
