An approach to the non-linearity of an ionization vacuum gauge at the upper limit of the measured pressure

Abstract

Beyond the upper limit of the linear region of an ionization gauge, there is a fall-off in the ion current with the increase of the measured pressure. This non-linear behaviour is to be expected by the theory of the non-selfsustaining discharge, from which it follows that the pressure corresponding to the maximum ion current may be expressed as p^=E/C, where E is the field strength between the electrodes and C is a constant. Thus the upper limit of the linear region will be extended as E increases. Four versions of gauge-electrode configurations capable of giving higher field strength as well as maintaining lower sensitivity have been under test, leading to the result that the upper limit of linearity has been extended from 10 −1 torr ab origine up to 1 torr, 2 torr, 6 torr and 10 torr, respectively. There is satisfactory agreement between these experimental data and the calculated values based on the above theory.