Design Of Level Meter For Cryogenic Dewar Of Pulsed High Magnetic Field

Recently, with the development of pulse magnet technology, pulsed high magneticfield has raised scientists’ attention because of its increment in the fundamental research,such as condensed state physics, materials science, and biomedicine. In the process ofdaily experiments in High Magnetic laboratory, cryogenic liquid needs to be used forproviding low temperature atmosphere. The liquid level needs to be shown during theexperiments therefore a convenient and accurate cryogenic liquid level meter is needed.This thesis introduces design theories of two newly designed cryogenic liquid levelmeters, and compares their performance to that of traditional level meter. The thesismainly contains following contents:Firstly, there’s a brief introduction of basic components of Wuhan National HighMagnetic Field Center, including: Power supply system, Controlling system, Measuringsystem and Cryogenic system. And it emphasizes the importance of using a propercryogenic liquid level meter under cryogenic system in Wuhan National High MagneticField Center.Secondly, it introduces working method, structure and application of several existedliquid level meter, including: ultrasonic level meter, radar wave level meter,magnetostrictive level meter, optical fiber level meter, superconductive level meter andcapacitive level meter. It also gives a brief analysis of their applicability of using undercryogenic system in Wuhan National High Magnetic Field Center.Thirdly, it introduces working method and design scheme of improved capacitivecryogenic liquid level meter. The improved capacitive cryogenic liquid level meter usestwo extra flat capacitors to measure the permittivity of the measured liquid and the gasabove it, and then makes an adjustment to the measured result. The improved capacitivecryogenic liquid level meter can increase the accuracy of measuring result, in compare to the traditional capacitive cryogenic liquid level meter.Fourthly, it introduces working method and design scheme of temperature measuringtype cryogenic liquid level meter. The temperature measuring type cryogenic liquid levelmeter measured the temperature of different points in the level sensor, and then judgewhether a certain point is under the liquid level or above it. It has advantages of stabilityand anti-interference.Finally, it gives results of cross test among two newly designed cryogenic liquid levelmeter and traditional capacitive cryogenic liquid level meters. It comes to a conclusionfrom analyzing the data that, the newly designed cryogenic liquid level meters canincrease the accuracy of measuring result significantly, in compare to the traditionalcapacitive cryogenic liquid level meter.