基于腔扰动法的原子气室复介电常数估计

Estimation of Complex Permittivity of Atomic Vapor-Cell Using Cavity Perturbation Technique

近年来,基于原子的微波测量因其具有将微波量转换为频率量进行测量的优势引起了学术界的广泛关注。由于频率量具有所有物理量中最高的测量精度,故这种新型微波测量手段具有极大的发展潜力。研究表明,目前限制微波测量精度的主要因素来自于微波场传感探头的原子气室本身。为了定量评估气室对场量测量的影响,该文首先准确评估了气室的结构尺寸和介电特性。作为原理性实验验证,采用S和X频段矩形微波腔扰动方法,对圆柱状原子气室的复介电常数做了测量评估。同时还简要讨论了其他可用于气室介电测量的方法。

Recently, atom-based microwave (MW) measurement has inspired great interest because of its potential ability to link the MW quantity with the international system of units (SI) second. The frequency has the highest measurement accuracy among all physical quantities, implying a great potential of atomic MW measurement. At present, the main factor limiting the measurement accuracy arises from atomic vapor-cell itself. In order to evaluate the effects of the vapor-cell on atom-based MW measurements, the structure parameters and permittivity of vapor-cell are firstly estimated in this paper. As a demonstration, the complex permittivity of a cylindrical vapor-cell is measured and evaluated through MW cavity perturbation technique at S and X bands. Finally, various methods used for the measurement of permittivity of vapor-cell are briefly discussed.