【摘要】：Overhauser磁力儀探頭中自由基溶液激發(fā)頻率的精度直接決定探頭輸出拉莫爾旋進(jìn)信號的質(zhì)量.為準(zhǔn)確獲得激發(fā)頻率,本文設(shè)計(jì)了一種Overhauser磁力儀探頭激發(fā)頻率測試儀.針對目前測試設(shè)備存在的分辨率較低、操作復(fù)雜等問題,采用高分辨率DDS作為可控射頻信號源;運(yùn)用ADC同步采集技術(shù),結(jié)合歸一化數(shù)據(jù)處理方法有效解決50MHz~100MHz范圍內(nèi)幅頻特性曲線不平坦的問題;采用射頻功放、小信號放大作為輔助測量通道,實(shí)現(xiàn)儀器的標(biāo)準(zhǔn)、輔助測量一體化.通過對探頭諧振腔的等效電路進(jìn)行仿真,得到微調(diào)電容對探頭諧振頻率和品質(zhì)因數(shù)的影響程度,并用商用探頭進(jìn)行測試,進(jìn)一步驗(yàn)證仿真結(jié)果;同時(shí)得到自由基溶液的極化度與射頻激發(fā)功率、激發(fā)時(shí)間的關(guān)系.最終實(shí)驗(yàn)結(jié)果表明,利用本文研制的Overhauser磁力儀探頭激發(fā)頻率測試儀,能夠準(zhǔn)確測量自由基溶液的激發(fā)頻率、頻率帶寬以及品質(zhì)因數(shù),還可用于在磁力儀設(shè)計(jì)過程中對激發(fā)功率和激發(fā)時(shí)間的確定,為進(jìn)一步設(shè)計(jì)Overhauser磁力儀奠定了基礎(chǔ).
[Abstract]:The precision of excitation frequency of free radical solution in the probe of Overhauser magnetometer directly determines the quality of Lamor precession signal output by probe. In order to obtain the excitation frequency accurately, a kind of Overhauser magnetometer probe excitation frequency tester is designed in this paper. In order to solve the problems of low resolution and complex operation of test equipment, high resolution DDS is used as the controlled RF signal source. The problem of amplitude-frequency characteristic curve unevenness in the range of 50MHz~100MHz is solved effectively by using ADC synchronous acquisition technology and normalized data processing method. RF power amplifier and small signal amplification are used as auxiliary measurement channels to realize the standard of instrument and the integration of auxiliary measurement. Through the simulation of the equivalent circuit of the probe resonator, the influence degree of the fine-tuning capacitance on the resonant frequency and quality factor of the probe is obtained, and the commercial probe is tested to further verify the simulation results. At the same time, the relationship between polarization degree of free radical solution and RF excitation power and excitation time is obtained. The final experimental results show that the Overhauser magnetometer probe excitation frequency tester developed in this paper can accurately measure the excitation frequency, frequency bandwidth and quality factor of free radical solution. It can also be used to determine the excitation power and time during the design of the magnetometer, which lays a foundation for the further design of the Overhauser magnetometer.
【作者單位】： 中國地質(zhì)大學(xué)地球物理與空間信息學(xué)院;中國地質(zhì)大學(xué)自動(dòng)化學(xué)院;近地面探測技術(shù)重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金(No.41474158,No.41504137) 國家重大科學(xué)儀器設(shè)備開發(fā)專項(xiàng)(No.2014YQ100817) 近地面探測技術(shù)重點(diǎn)實(shí)驗(yàn)室開放課題(No.TCGZ2015A008) 武漢市科技局應(yīng)用基礎(chǔ)研究計(jì)劃項(xiàng)目(No.2016010101010013)
【分類號】：TM935.1

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