使用石英振蕩器製作交流梯度磁力計之可行性研究

The implementation of AC Gradient Magnetometer Using Quartz Resonator

丁章(Zhang Ding)

指導教授 ： 吳啟彬

中原大學/理學院/物理研究所/碩士(2021年)

https://doi.org/10.6840/cycu202100452

摘要

石英諧振器因為有很高的品質因數而被廣範的運用到各種傳感器中。我們希望利用它是壓電材料和有高 Q 值的特性來製作一臺簡易的磁力計，並擁有不錯的靈敏度。

我們搭建了一套可以同時施加直流磁場和交流梯度磁場的系統，將四氧化三鐵粉末黏在石英諧振器的尖端上，用交流梯度磁場使四氧化三鐵粉末受力驅動石英在共振頻率振蕩，直流磁場改變四氧化三鐵粉末的磁矩，進而影響石英的壓電電壓。

測量石英諧振器的電壓作為磁場強度的函數，通過理論算出磁矩和直流磁場的關係。觀察四氧化三鐵粉末的磁矩隨直流磁場強度變化的改變，並與沒有四氧化三鐵粉末的石英諧振器比較。最終量到了 10^−9 Am^2 左右的磁矩，成功製造了一臺簡易的磁力計，雖然與其他交流梯度磁力計有差距，但也找到了改進的方向。

關鍵字

交流梯度磁力计

並列摘要

The high quality factor of quartz resonators leads to the vast application of quartz tuning forks as various sensors. We hope to make use of its piezoelectric properties and high Q value to implement a simple magnetometer with good sensitivity.

We have built a system that can simultaneously apply a DC magnetic field and an AC gradient magnetic field. The ferrite powder is glued to the tip of the quartz resonator, and an AC gradient magnetic field is used to apply force to the ferrite powder to drive the quartz to oscillate at the resonance frequency. The DC magnetic field changes the magnetic moment of the ferrite powder, and then affects the piezoelectric voltage of the quartz.

By measuring how the piezoelectric voltage output changes with the DC magnetic field, and comparing it with the result from a quartz resonator without magnetic particles, we can detect a magnetic moment of about 10^−9 Am^2, and a simple magnetometer was successfully established. Although its present performance is not as good as the other AC gradient magnetometers, it does lead us to certain directions of improvement.

並列關鍵字

AC gradient magnetometer

參考文獻

[1] M. Todorovic and S. Schultza, Miniature high-sensitivity quartz tuning fork alternating gradient magnetometry, Applied Physics Letters. 73, 3595 (1998). I, II

[2] 連益慶, 舒貽忠, 壓電振動能量擷取系統介紹, 工業材料雜志. 263, 130 (2008). 1

[3] Khaled Karrai, Robert D. Groberb, Piezo-electric tuning fork tip—sample distance control for near field optical microscopes, Ultramicroscopy. 61, 197 (1995). 1

[4] 徐軍, 石英音叉諧振式溫度傳感器及關鍵技術的研究, 哈爾濱理工大學. 工學博 士學位論文 (2014).1

[5] Robert D. Grober, Jason Acimovic, Jim Schuck, Dan Hessman, Peter J.