基本信息
摘要：1346612 Detecting formation of thin films ANALYTICAL INSTRUMENTS Ltd 30 March 1972 [3 April 1971] 8624/71 Heading G1N The presence of a film or layer on a radioactive source is detected by the resulting drop in ionisation current in an atmosphere surrounding the source. A dew point meter is shown, and includes a radioactive source 2, e.g. tritium or nickel 63, and a collector electrode 1, the radioactive source being cooled until a drop in ionisation current collected at electrode 1 is indicated on an indicator 6. The temperature is then noted on a device 8. In Fig.2 (not shown), the output of the amplifier 5 is used to energise a heater to thereby control the rate of cooling of the source 2.
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