| 摘要 |
A method and apparatus for monitoring particulates which are borne by a surrounding gaseous medium, such as found in smokestack or the like, through interception of the particulates by a hot filament having a bias potential in the range of about 100 to 1000 volts whereupon each particulate decomposes into a burst of ions which is collected by a nearby electrode at ground potential, by counting those bursts which produce a predetermined total charge and, at the same time, measuring the DC electric current produced by the bursts and other ion exchange between the hot filament and the electrode. The filament operates at a temperature level wherein infrared and visible radiations are emitted, such radiations being monitored by a phototransistor which receives the radiations. The electrical signal from the phototransistor is employed in a feedback loop whereby the power to the filament is either increased or decreased to maintain the detected radiation level and therefore the filament temperature at a prescribed value.
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