Discharge Ionization Current Detector

摘要

A technique for reducing an electromagnetic noise entering an electrode or a drift of a signal due to a fluctuation in the ambient temperature is provided to improve the S/N ratio of a signal originating from a component of interest. A dummy electrode 11 having the same structure as an ion-collecting electrode 10 is provided within a lower gas passage 14 at a position where dilution gas with no sample gas mixed therein flows. A differential amplifier 14 is provided to perform differential detection between output A of a current amplifier 21 connected to the ion-collecting electrode 10 and output B of a current amplifier 22 connected to the dummy electrode 11. The differential signal is free from a common mode noise or drift and hence accurately reflects the amount of the component of interest.