Abstract
An ionization vacuum gauge with carbon nanotube (CNT) cathode was designed for measurement of ultra high vacuum (UHV). The sensor was constructed based on Bayard-Alpert type gauge. The key index of the control unit is determined by theoretical analysis and experimental results. A customized detection circuit was designed considering the characteristics of the output ion current of the sensor, the performance of which, such as linearity, noise, bandwidth and gain, were determined by a series of tests and calibrations. At last, the vacuum measurement range and uncertainty of this gauge were determined. The test results showed that the lower limit of the CNT-cathode ionization vacuum gauge enters 10-8Pa, The measurement uncertainty is about 4.0% in the pressure range of 10-4Pa-10-7Pa. This work can provide a new solution for UHV measurement.
Highlights
ultra high vacuum (UHV) measurement is widely used in high-energy physics, nuclear fusion, material science, optics, quantum physics and other fields
Through the step adjustment of precise digital to analog converter (DAC) in the control circuit, the zero-point output of the four groups of feedback resistors can be controlled below 5 mV under different measurement environments, and the influence on the output results is less than 0.1%
This paper introduced the development and realization of an UHV ionization gauge based on Carbon Nanotube (CNT) cathode, in which CNTs were used to replace the traditional hot cathode
Summary
UHV measurement is widely used in high-energy physics, nuclear fusion, material science, optics, quantum physics and other fields. The traditional hot cathode ionization gauges for UHV measurement are suffered from the soft X-ray effect, electron excitation deactivation (ESD) effect and thermal cathode effect, leading to an insufficient lower measurement limit.[1] Besides, this kind of instruments consume more power, which is not available in certain application environments, such as space application. The application of the new field emission cathode is considered as a key step for solving the above problems. Carbon Nanotube (CNT), among a number of field emission materials, has become an ideal choice to make field emission cathode owing to its large length-to-diameter ratio, good conductivity, excellent mechanical properties and chemical stability. An ionization vacuum gauge with CNT cathode was developed, which exhibited obvious advantages in UHV measurement.[2]
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