GB1406533A - Collection and measurement of electrical charges in a charge- carrying fluid - Google Patents

Abstract

1406533 Analysing gases AGENCE NATIONALE DE VALORISATION DE LA RECHERCHE 3 Jan 1973 [4 Jan 1972] 326/73 Heading G1N Apparatus for the measurement of electric charges in an ionised gas comprises Figs. 1 and 2 (i) a collector electrode 4, connected to earth through an electrometer amplifier to measure the charge current; (ii) a polarized deflector electrode 3 (of the same sign as the charges to be measured), and (iii) a compensating electrode 5 not exposed to the sample gas and oppositely polarized to the deflector electrode, in order to compensate for the interelectrode leakage, so that the collector electrode is at earth potential in the absence of a charged sample. In a modification Figs.3 and 4 (not shown), a pair of detector cells may be arranged in a common structure with oppositely polarized deflector electrodes, so that the concentration of positive and negative ions may be measured separately. Provision may be made also to sum these signals, Fig.4. Circuitry. The electrometer amplifier 2 may comprise a "varactor" and may be mounted in a cooled thermally insulated housing 27, Fig.5, for stability and reduction of thermal noise. The amplifier is mounted on the cold surface of a thermo-junction (Peltier) cooling element 26 which has its hot face connected through a copper block 30 to a finned radiator 33 outside the housing.