可变电压源在热导检测器中的应用

在可变电压源电路中,通过传感器上的电流恒定,改变桥路中支路电阻比值大小,能够一定程度上提高热导检测器(TCD)的灵敏度。同时还分析了可变电压源在铼钨丝与热敏电阻(NTC)作为传感器上的应用,在铼钨丝(130Ω)作为传感器实验中,其它条件相同时,通过铼钨丝上电流分别在20mA、40mA、60mA的比较,发现桥路输出信号与铼钨丝上通过电流的3.5次方成比例。在热敏电阻(NTC)作为传感器实验中,选择材料常数β值大的热敏电阻作为传感器,有利于提高桥路的信号输出。

Application of variable voltage source in thermal conductivity detectors

The sensitivity of thermal conductivity detector （TCD） could be enhanced by keeping sensor current constant and changing the ratio of branched resistances of the bridge circuit in the variable voltage source circuit. The application of the variable voltage source is presented when W-Re and thermistor （Negative Temperature Coefficient） are used as sensing cells. In the experiments of W-Re（130f~） as the sensor, it was found that outputs of the bridge circuit are 3.5th-power proportion of the currents through W-Re under the same other conditions according to the results when the current is 20mA, 40mA, and 60mA respectively. In the experiments of thermistor （Negative Temperature Coefficient） as the sensor, it is helpful to increase the output signals of the bridge circuit by choosing the thermistor with bigger material coefficient fl as the sensor.