被动型氢原子钟氢原子束流量控制系统

发布时间：2018-04-19 15:35

本文选题：氢原子钟 + 氢原子束流量　；参考：《东南大学》2016年硕士论文

【摘要】：氢原子钟的长期频率稳定度主要受限于系统效应,包括氢原子束流量的变化、腔牵引效应、壁移和二级多普勒效应等;短期稳定度则通常取决于系统的基本热噪声。为进一步提高氢原子钟的频率稳定度,必须考虑各个方面的影响并加以改善。本文通过分析氢原子束流量对氢钟频率稳定度的影响,提出应将流量的变化水平限制在5%以内,并为此设计了流量控制系统。本文首先分析了氢原子钟内真空系统的气体流动特性,提出可将氢原子束流量的测量转换为对系统真空度的测量。对比各种真空测量方法后,系统采用热传导真空计的原理测量真空度,并做出了论证。最后,论文在真空度检测的基础上设计了闭环控制系统,通过调节钯银合金管的加热功率,实现对氢原子束流量的控制。系统首先设计了氢原子束流量测量电路,选用C8051fl21 MCU作为核心控制器,并设计了环境温度检测模块、流量给定模块、PWM控制的加热模块、数据通信模块和电源模块等相关电路。继而设计了流量控制软件,实现数据的采集和处理,以及单片机与上位机的通信等功能。实验平台搭建完成后,系统对比普通的PID控制算法,选择了Dahlin算法作为控制算法,并确定了Dahlin数字控制器的控制参数和控制流程。最后设计和执行了一系列氢原子束流量控制实验以评估系统的控制性能。实验数据表明,系统能够实现氢原子束流量调节功能,控制精度优于99.56%,相对稳定度优于2%,重复性好,可达到设计目标。
[Abstract]:The long-term frequency stability of hydrogen clock is mainly limited by the system effect, including the variation of hydrogen beam flux, cavity traction effect, wall shift and second-order Doppler effect, etc. The short-term stability is usually determined by the basic thermal noise of the system.In order to further improve the frequency stability of hydrogen atomic clock, all aspects must be considered and improved.Based on the analysis of the effect of hydrogen atomic beam flow rate on the frequency stability of hydrogen clock, it is proposed that the flow rate should be limited to less than 5%, and a flow control system is designed for this purpose.In this paper, the gas flow characteristics of a vacuum system in a hydrogen atom clock are analyzed, and it is proposed that the measurement of hydrogen atom beam flow can be converted into a measurement of the vacuum degree of the system.After comparing various vacuum measurement methods, the system uses the principle of heat conduction vacuum gauge to measure the vacuum degree, and makes a demonstration.Finally, a closed-loop control system is designed on the basis of vacuum measurement. By adjusting the heating power of the Pd-Ag alloy tube, the flow rate of hydrogen atom beam can be controlled.Firstly, the circuit of hydrogen atom beam flow measurement is designed, and C8051fl21 MCU is selected as the core controller. The environmental temperature detection module, the flow given module, the PWM controlled heating module, the data communication module and the power supply module are designed.Then the flow control software is designed to realize the data acquisition and processing, as well as the communication between MCU and host computer.After the construction of the experimental platform, the system compares the common PID control algorithm, selects the Dahlin algorithm as the control algorithm, and determines the control parameters and control flow of the Dahlin digital controller.Finally, a series of hydrogen beam flow control experiments are designed and implemented to evaluate the control performance of the system.The experimental data show that the system can realize the function of hydrogen atom beam flow regulation, the control precision is better than 99.56, the relative stability is better than 2, the repeatability is good, and the design goal can be achieved.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TP273;TM935.115

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