JPS5756749A - Detector of very small quantity of ion - Google Patents

Abstract

PURPOSE:To improve S/N and to obtain a detector having a strong stain resistance, by applying an alternating current between an electrode for ionization and electrode for ion collection and removing a dark current interferring the detection at the detector of a very small quantity of ion in gas. CONSTITUTION:An alternating voltage is applied to gas containing Na between an electrode (filament) 1 ionizing Na by heating by a power source for heating 5 and an electrode for ion collection2 using a collection power source 6 as an alternating current, at a leakage detection of a very small quantity of Na in the gas for a high electric speed breeder. Hereby, both of a dark current Ro flowing through an insulation bushing 4 of the electrodes 1, 2 and a signal current So, are turned to the alternating current and there is no dependent property of positive or negative polarity because of flowing the current Ro through an insulator. Further, dimensions of a positive and negaive signals are the same and the current Ro can be made small remarkably by denying by the signal treatment of succeeding circuit. Even when the variation of insulation resistance of the insulator 4 is produced by a temperature, dirt or mositure adhesion, it has a little influence on these phenomena because of producing the same positive and negaive signal. A detection signal S of until about 10<-12>g/cc Na<+> ion is detected with a good accuracy.