守时原子钟性能缺陷改善方法研究

Study on the Improving Methods of the Atomic Clock Performance At present, the hydrogen mase and the cesium clock are two kinds of mainly, continuously operating atomic clocks for time keeping in most of time laboratories all over the world. As all well known, the hydrogen mase has excellent shortly stable peculiarity, so it is selected as frequency source of UTC(k) to output high qualily physical signals. While the cesium clock is usually used to keep the long-stability of UTC(k) with its upstanding long-stability. Because of its physical structure and operating characteristic, the hydrogen mase has visible frequency drift which makes its long-stability gradually fall with time. Although the long peculiarity of the cesium clock is very stable, its short-stability is lower one amount than the hydrogen mase at least. This project will use the atomic clock resources and relative time-frequency facilities in the key laboratory of time and frequency primary standards, Chinese Academy of Sciences, and pass through theoretical researches and experimental analysis to put forward two methods. The first method is to improve the long-stability of the hydrogen mase which corresponds with the cesium clock's one, while its short-stability is immovable. The second one is to meliorate the cesium clock's short peculiarity with inherent long-stability.

目前，全球绝大多数时间实验室的守时原子钟主要由氢原子钟和铯原子钟组成。氢原子钟具有良好的短稳特性，一般作为UTC(k)的频率源，提供高品质的物理输出信号；铯原子钟有良好的长期稳定性，主要用于守时实验室UTC(k)长期性能的保持。由于物理结构及其自身工作特性，氢原子钟存在频率漂移效应，从而使氢原子钟的长期稳定度随着时间的推移不断降低；铯原子钟的长期性能非常稳定，而短期稳定度与氢原子钟相比低一个量级。 本课题利用国家授时中心时频基准重点实验室现有的原子钟资源及相关时频设备，基于理论研究与实验分析，获得氢原子钟频率漂移和铯原子钟频率波动的规律；在数学建模的基础上结合实测数据，提出软硬件相结合的原子钟物理输出信号品质改善方法。该方法在不改变氢原子钟短稳特性的同时，使其长稳性能与铯钟相当；在保持铯原子钟长稳性能的同时，短期稳定性提高半个量级。

本项目对目前两类主流守时原子钟的性能缺陷的改善进行了实验研究，并开发了用于频率修正的实验平台和相关软件。基于国家授时中心不可多得的原子钟资源和守时比对系统，利用国际权度局（BIPM）每月一次公布的上月NTSC原子钟的性能参数——相位、速率、频率漂移，分别提出了削弱氢原子钟的频率漂移和减小铯原子钟频率波动的方法，通过数学模型结合NTSC原子钟本地测量比对数据进行实验钟的性能参数预报，将预报参数以频率干预的方式通过实验平台中的专用设备——相位微调仪对原子钟输出的频率信号进行干预，实现降低氢原子钟频率漂移半个量级目的同时提高其长稳性能；首次提出利用软硬件结合的方式减小铯原子钟的频率波动提高其短稳性能，实验结果表明对铯钟频率的干预在采样间隔1000秒以下稳定度可以提高半个量级，并不会破坏铯钟的长期频率特性。在用项目设计方法削弱氢原子钟频率漂移量值的过程中，氢钟的短稳指标会略有变差，原因是氢钟本身的漂移变化是连续的，而本项目采用的软硬件结合的方法计算需要时间,硬件操作更需要时间，所以频率漂移修正过程是阶梯式的。