| Vacuum technology plays an important role in the field of frontier technology and electronic vacuum devices.However,there is still a lack of reliable method to measure the internal vacuum degree of electronic vacuum devices.It is extremely difficult to monitor the pressure of sealed electronic vacuum devices in real time.In order to solve these problems effectively,a vacuum pressure sensor based on field emission of carbon nanotube and gas absorption has been developed and investigated in this work.The carbon nanotubes with strong adhesion are prepared on Hastelloy alloy by thermal CVD method,and then the carbon nanotubes are used as field emission cathode material in bipolar structure.The experiments show that in the condition of low-current field emission,the CNT emitter demonstrates the sensing effect that the emission current increases with increasing the vacuum pressure.Based on such sensing property,a miniature sensor to measure the internal vacuum inside a cavity is designed.This sensor has the advantages of wide measurement range(1×10-7?1×10-2Pa),small dimension?4×5×9mm?,low operation voltage?<2kV?,low power consumption?5?W?0.8 W?,no interference to the device,long life,and so on.In order to research its application performance,the sensor has been tested in industrial environment.The tests show that the sensor demonstrates good sensing property in the range of 6×10-6?1×10-3 Pa.Besides,the sensor has been further tested by sealed in X-ray tube.During 40 day test for two X-ray tubes with sensors respectively,the internal vacuum degrees of the two X-ray tubes are in the scale of 2.12×10-4?5.14×10-4 Pa,and the vacuum degrees of the two X-ray tubes become lower gradually.The results are agree with the theoretical expectation.From the investigation,the sensor has demonstrated the function of measuring the vacuum inside sealed devices in real time.In order to make this new sensor an effective method to measure the internal vacuum in the vacuum electronic devices,the application performances of the sensor in sealed vacuum electronic devices will be further investigated,with the optimizations of the preparation of emission materials,the design of sensor,and the working mode. |
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