高准确度铯-氦光泵磁强计的粒子数密度配比研究
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摘要
为研发高准确度铯-氦光泵磁强计探头的制备工艺,该文通过分析铯、氦两种混合物质的气室内各组分间的潘宁电离和自旋交换碰撞过程,从理论上给出铯-氦磁强计的最佳粒子数配比关系N_(Cs)∶N_(He)≈1.9∶1。为验证该理论,搭建一套铯-氦磁强计系统,分别通过调节温度和激励微波来控制铯原子和氦原子的数密度,当磁共振信号达到最优化状态时,测量铯氦粒子数比值为N_(Cs)∶N_(He)≈1.6∶1。考虑到理论计算时对亚稳态氦原子退极化率的保守估算和实验过程中对气室内部温度的测量误差,该理论值和实验结果吻合度较为一致。研究结果表明:在制作铯-氦光泵磁强计探头气室时,铯原子与亚稳态氦原子的原子数密度比值应该介于1.6~1.9之间。
In order to develop the technique of making sensors for the Cs-He optical magnetometer,the Penning ionization and spin-exchange collision process happening in the cesium-helium mixture vapor chamber are analyzed, and the optimal number density ratio of the mixture is calculated, which gives N_(Cs)∶N_(He)≈1.9∶1. To check this theoretical result, a Cs-He magnetometer system is built, where the number density of Cs and He can be controlled by adjusting the temperature and microwave discharge respectively, when the magnetic resonance signal reaches the best performance, the number density ratio of the mixture is measured, which is N_(Cs)∶N_(He)≈1.6∶1.Considering the upper limit estimate of the depolarization of metastable helium in the theory and the temperature error of the chamber center in the experiment, the theoretical number fits well with the experimental results. The results show that the optimal ratio of Cs/4 He number density of a Cs-He magnetometer should be between 1.6 and 1.9.
In order to develop the technique of making sensors for the Cs-He optical magnetometer,the Penning ionization and spin-exchange collision process happening in the cesium-helium mixture vapor chamber are analyzed, and the optimal number density ratio of the mixture is calculated, which gives N_(Cs)∶N_(He)≈1.9∶1. To check this theoretical result, a Cs-He magnetometer system is built, where the number density of Cs and He can be controlled by adjusting the temperature and microwave discharge respectively, when the magnetic resonance signal reaches the best performance, the number density ratio of the mixture is measured, which is N_(Cs)∶N_(He)≈1.6∶1.Considering the upper limit estimate of the depolarization of metastable helium in the theory and the temperature error of the chamber center in the experiment, the theoretical number fits well with the experimental results. The results show that the optimal ratio of Cs/4 He number density of a Cs-He magnetometer should be between 1.6 and 1.9.
引文
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[9]DMITRIEV S P,DOVATOR N A,KARTOSHKIN V A,et al.Indirect optical orientation of atoms in He-Cs gas discharge plasma:an explanation of anomalous ratio of the magnetic resonance signals[J].Optics and Spectroscopy,2016,120(2):207-211.
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[11]DMITRIEV S P,DOVATOR N A,KARTOSHKIN V A.Spin exchange and chemi-ionization during collisions of polarized metastable helium atoms with ground-state cesium atoms[J].Technical Physical,1999,44(9):1033-1037.
[2]BUDKER D,ROMALIS M V.Optical magnetometry[J].Nature Physics,2007,3(4):227-234.
[3]BLINOV E V,ZHITNIKOV R A,KULESHOV P P.Alkali-helium magnetometer[J].Zh Tekh Fiz,1979,49(3):588-596.
[4]ALEKSANDROV E B.Advances in quantum magnetometry for geomagnetic research[J].Uspekhi Fizicheskikh Nauk,2010,180(5):509-519.
[5]BLINOV E V,ZHITNIKOV R A,IL’IN E A,et al.Metrological analysis of alkali-helium magnetometers[J].Measurement Techniques,1986,29(11):1078-1082.
[6]SHIFRIN V Y,ALEXANDROV E B,CHIKVADZE T I,et al.Magnetic flux density standard for geomagnetometers[J].Metrologia,2000,37(3):219-227.
[7]BLINOV E V,ZHITNIKOV R A,KULESHOV P P.Alkali-helium magnetometer[J].Geophysical Apparatus,1982,79:9-21.
[8]BLINOV E V,ZHITNIKOV R A,KULESHOV P P.Spin orientation of metastable He-4 atoms in collisions with optically oriented cesium atoms[J].Pis’ma Zh Tekh Fiz,1976(2):305-309.
[9]DMITRIEV S P,DOVATOR N A,KARTOSHKIN V A,et al.Indirect optical orientation of atoms in He-Cs gas discharge plasma:an explanation of anomalous ratio of the magnetic resonance signals[J].Optics and Spectroscopy,2016,120(2):207-211.
[10]ALCOCK C B,ITKIN V P,HORRIGAN M K.Vapor pressure equations for the metallic elements-298-2500K[J].Canadian Metallurgical Quarterly,1984,23(3):309-313.
[11]DMITRIEV S P,DOVATOR N A,KARTOSHKIN V A.Spin exchange and chemi-ionization during collisions of polarized metastable helium atoms with ground-state cesium atoms[J].Technical Physical,1999,44(9):1033-1037.