原子频标参数优化新方法

参数优化是原子频标性能优化中的很重要的环节,针对目前此领域参数实验不完整的现状,通过建立原子频标参数优化的均匀设计模型,以少点数实验、小误差优化结果解决传统参数优化实验过程的烦琐问题及改善最优工作参数点,并针对具体一台原子频标给出详细的诸如灯温、腔温等参数值.     

NI立足测试测量，助力5G

The SI “second” is realized by caesium primary frequency standards (PFSs) using laser cooled atoms in a fountain configuration. Four sub systems and operation procedure of the NTSC-F1 primary frequency standard are introduced in the paper. The frequency stability of NTSC-F1 is 3.0×10-13/τ-1/2 compared to hydrogen maser. Four terms of frequency shift and uncertainty including second order Zeeman frequency shift, cold collision shift, gravity shift and blackbody shift are evaluated. The improvement of NTSC-F1 is introduced.     

AT1原子时算法的研究

原子时算法的选用将对原子时标的准确度和稳定度有着很大的影响.本文从AT1实时原子时算法的基本原理出发,结合中国计量科学研究院守时钟房中原子钟的实际情况,对AT1实时原子时算法进行了系统的研究,给出了其算法流程,特别是,对一些关键量进行了分析和数据验证,给出了期望钟组的计算方法,最后得到了期望的钟组计算结果.该结果表明,钟组时间的频率稳定度大大优于每台单个钟的频率稳定度,满足技术要求.     

Development of diode‐pumped solid‐state laser HALNA for fusion reactor driver

The diode‐pumped slab laser for inertial fusion energy driver has been demonstrated, which produces the 1053‐nm output energy of 10 J at 10 Hz. The glass slab laser amplifier has been pumped by quasi‐CW 290‐kW AlGaAs laser‐diode arrays at 803 nm. The optical system can compensate for thermal effects by use of zigzag optical propagation, image‐relayed telescope, and 45^° Faraday rotator. The output energy of 10.6 J at 1 Hz with the optical‐to‐optical conversion efficiency of 19.9% has been successfully obtained. Also, the 10‐Hz operation has been performed with an output energy of 5.1 J. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(2): 27–35, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20288     

High‐repetition‐frequency short pulses in a VHF discharge‐excited slab‐type carbon dioxide laser using an ultrasonic vibrator

We propose a novel method for producing high‐repetition‐frequency short pulses with a halved confocal configuration consisting of an unstable concave–convex resonator in a very high frequency (VHF) discharge‐excited slab‐type carbon dioxide laser. This method utilizes a fully reflective concave mirror with variable curvature which can be controlled by a piezoelectric device. In general, slab lasers are modulated directly by varying the pulse voltage. However, because plasma fluctuation occurs at the pulse transitions, the repetition frequency is less than 10 kHz and the minimum pulse width is 1 µs. On the other hand, in our method there is no disturbance of the plasma, because the power source is not modulated. There is also little mechanical constraint, because we use a piezoelectric device. As a result, pulse shortening with a high repetition rate is possible. The pulse shape is well reproduced by a three‐level rate equation. The mechanism of the method involves changes in ejection efficiency with periodic variation of the radius of curvature of the mirror. Good agreement between observations and calculations was also obtained for the peak power and the pulse width. In this paper we compare measurements with calculations. The possibility of achieving high repetition rate oscillation and pulse shortening by this method is examined. The results confirm the possibility of achieving a repetition frequency between 1.4 kHz and 170 kHz. The shortest pulse width that can be achieved is 160 nanoseconds. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 1–7, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10127     

小型频标与频率稳定度测量系统

在理解铷原子频标及时测量系统基本原理的前提下,提出了一种改进型的铷原子频标及频率测量系统,对该系统的设计方案进行了深入的剖析和讲解。分析各部件对系统频率稳定度的影响,设计出高精度的恒温控制压控石英振荡器、DDS频率源、调相电路、晶体管及阶跃二极管倍频电路、伺服电路等,优化电路设计和参数选择,实现优势组合与互补的铷原子频标系统。利用铷原子频标输出的标准频率信号作为测量系统的标准频率输入,引入DDS实现差拍法和多模式频差倍增法[1]相结合的方法,实现高精度的可测量各种频率的频率稳定度测量系统。     

真空调频原子力显微镜系统设计

原子力显微镜(AFM)作为微观领域表征物质性质的强有力工具,在科学研究中被广泛应用。现有的商业原子力显微镜的工作模式大都为调幅模式(AM-AFM),受品质因子Q的影响限制了进一步的高分辨率成像研究。为进一步提高分辨率,设计研发了调频原子力显微镜(FM-AFM),分析了影响系统分辨率的重要因素,并且设计了真空系统,以此提高探针悬臂的品质因子Q。本文对真空环境下FM-AFM的系统性能进行了实验和研究,从系统灵敏度以及测量效果等方面讨论了真空环境下FM-AFM相较于大气环境下的优越性。系统功率谱密度达到10 mHz/√Hz,系统灵敏度Δf≤0.02Hz,探针悬臂的品质因子Q达到14212,突破了原子力显微镜中的Q限制。     

外场环境下频率测量系统的设计

提出在外场使用环境下的频率测量系统的设计方法,用于外场复杂测试环境,设计满足机动化、一体化测量要求。系统采用连续采样的频差倍增法,采用双平衡混频器实现混频模块、滤波电路,提高测量分辨能力,根据GPIB接口特点,采用D7210C和75160BN,75161BN芯片实现计算机与仪器与测量仪器间的双向、异步、准确可靠的数据通信任务,编写软件,采用自动化测量方式,完成外场环境下原子频标的频率测量。通过对实验室和外场的比对试验数据得出系统满足测试要求,设计的系统1s比对不确定度指标达到4×10E-13。     

激光引信中发射单元的设计

设计了用于机载激光引信的激光脉冲测距发射单元,该发射单元由激光器和驱动电路构成。激光器选择纳秒级脉冲大功率固体激光器,采用半导体激光二极管作为泵浦源,提出了一种获取同步信号的方法,并对其整体结构进行了考虑。为满足引信特殊需要,为半导体泵浦固体激光器设计了专用驱动电路,解决了固体激光器在不同温度下重复频率不稳定性问题,避免了使用体积庞大的致冷器。激光发射单元工作可靠,在很大温度范围内重复频率稳定并可灵活可调。5V电源时,输出峰值功率达2018W、脉宽3.3ns、重复频率达10kHz。     

溯源用低阻抗冲击电压标准波源

本文介绍了可产生IEC60060-1中规定的雷电全波的低阻抗冲击电压标准波源的原理及其不确定度评定。冲击电压标准波源为小型的Max发生器,其电压峰值U_p、波前时间T₁、波尾时间T₂都可以根据脉冲形成回路的元器件参数计算得到。该标准波源的输出电压波形峰值为10V-1000V,输出波形参数不确定度(置信概率95%,包含因子k=2)为：峰值U_Up：5×10_-4,波前时间U_T1:4×10_-3,半峰值时间U_T2: 4×10_-3,。采用PTB校准过的14Bit数字记录仪测量低阻抗标准的输出波形,并将测量结果与理论计算值进行比较。连续重复20次,最大相对标准偏差为2.7×10_-4。在六个月内各电压点峰值长时稳定性在0.2‰内。负载分别为7.95kΩ和1MΩ,理论计算波形参数的区别与测量结果吻合。表明该低阻抗冲击电压标准波源既可校核数字记录仪也可校准电阻分压器。     

高精度频标比对及分析系统设计

为了解决频率时域参数短期特性和长期特性的高精度测量问题,基于频差倍增技术、无间隙连续采样技术和数字比相技术研制了高精度频标比对装置,建立了一套高精度频标比对及分析系统。依据检定规程,利用Visual Basic开发环境,编写了原子频标和高稳晶振的自动检定软件,在计算机控制下,可以实现稳定度、准确度、日波动、老化率、漂移率、开机特性、复现性等的自动检定、结果数据自动处理、证书打印等功能。     

基于FPGA进位链的铯光泵磁力仪频率测量方法

铯光泵磁力仪输出拉莫尔频率,需要通过频率测量换算得到磁场值,频率测量的精度直接关系到磁测结果的准确性。提出了一种基于FPGA进位链的铯光泵磁力仪频率测量方法。首先采用加法器将 FPGA中的专用进位连线资源级联成进位链,然后基于时间内插的原理实现对拉莫尔频率的测量。与其他频率测量方法相比,该方法只需要FPGA编程即可实现,不需要额外的硬件消耗。对原理样机的测试结果表明,系统可行性好,测量精度高,以低成本、高灵活性的方式实现了铯光泵磁力仪的频率测量。     

基于频差倍增法的多通道铯原子频标检定系统

在测控、导航、雷达等领域,为了保证时间和频率的统一,需要对时统的铷钟及高稳晶振等设备进行高精度频率测量.根据频差倍增法测试原理,以铯原子频率标准FTS4040A为核心,设计开发了一套多通道的铯原子频标自动检定系统.首先介绍了系统软、硬件的设计情况,分析了频率测量系统常用的频差倍增技术,然后对基于频差倍增法的测试原理以及系统的关键技术进行了较为详细的阐述.结果表明,系统实现了同时检定14台被检设备各项指标的能力,并提高了测量精度.     

激光汇聚原子系统中基于USB接口的数据采集

在激光汇聚铬原子沉积研究中,需要用激光冷却铬原子,以压缩铬原子束的发散角.因此,必须将激光频率锁定在铬原子的7S3→7P40跃迁谱线上.为了实现对激光稳频状态的监测,设计了一套基于USB2.0接口的数据采集系统.系统选用EZ-USB FX2系列的CY7C68013作为USB控制芯片.利用LabVIEW开发了可视化界面.CY7C68013接受PC发出的指令,控制A/D转换电路采集稳频信号,并将其传输给PC.由PC完成数据的显示和存储.系统还设置了失锁报警功能,实现了对稳频的监测.     

原子干涉重力仪集成光源系统综述

高精度重力测量是进行惯性导航、大地测量、空间科学、海洋探测、基础物理研究的重要观测手段,高精度的重力仪一直是科学研究追求的目标。原子干涉重力仪能够提供uGal量级的绝对重力加速度值,是获取高精度重力信息的重要仪器之一,其集成光源系统的设计及实现对其实用化和商业化具有重要意义。首先介绍原子干涉重力仪激光系统的输出需求,然后对国内外典型集成光源系统的相关研究发展进行综述,分别介绍了基于自由空间和光纤传输的两种光源系统的实现方案和发展现状,重点阐述了其稳频、跳频、稳功率等关键技术。最后,对原子干涉重力仪集成光源系统的进行了总结与展望。     

短期和中长期电压稳定仿真及评价

阐述了短期及中长期电压稳定分析方法和建模要求,并针对我国电网仿真分析的现状,指出了电压稳定仿真和建模方面存在的主要问题;结合实际电网的短期及中长期电压稳定仿真计算,分析了短期电压崩溃和中长期电压崩溃过程的事故特征,并对电压失稳机理、暂态电压稳定和中长期电压稳定的评价方法做了进一步的探讨。     

交流励磁抽水蓄能机组变下垂系数调频控制策略

针对固定下垂系数控制存在抑制频率波动的阻尼不足的问题,提出一种基于惯性环节的交流励磁抽水蓄能机组变下垂系数调频控制策略。首先,基于交流励磁抽水蓄能机组运行特点,分别建立了可逆水泵水轮机和交流励磁电机的数学模型以及交流励磁抽水蓄能机组控制模型;然后,考虑频率变化率和频率偏差值对系统频率动态调节影响,引入下垂系数-系统频率变化率(R-df/dt)函数,并通过检测电网频率变化和机组转速,获得幅值随频率变化率动态变化的下垂系数,基于此,提出一种基于惯性环节的变下垂系数调频控制策略,并给出了参数整定方法。基于MATLAB/Simulink平台,搭建含交流励磁抽水蓄能机组的电力系统3机仿真模型,并进行系统频率特性的仿真分析。仿真结果表明,所提控制策略可有效提升机组在发电、电动工况下的频率响应能力,提高了电力系统的频率稳定性。     

Development of a laser radar using LDS dye and sum frequency generation for NO2 measurement

A laser radar for measuring vertical concentration profiles of atmospheric NO₂ was developed. The laser transmitter uses an LDS765 dye laser pumped by a Nd:YAG laser. The dye laser output is converted to wavelengths 446.8 and 448.1 nm, which are used for NO₂ measurement, by sum frequency generation (SFG) using a pair of KD^*P crystals. The dependence of the LDS765 dye laser output on wavelength and dye concentration was investigated, and the performance of the laser transmitter was evaluated. Compared to the Coumarin 445 dye laser conventionally used for NO₂ measurement, this laser transmitter represents a significant improvement in output stability, as well as in maximum output energy and overall conversion efficiency. Using the newly developed laser radar, NO₂ concentrations of 20 to 40 ppb were measured for vertical range 500 to 1000 m, which were in rough agreement with values monitored on the ground. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 144(2): 26–33, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10231     

Development of an extremely precise buffer amplifier for AC shunt standards at audio frequencies

The National Metrology Institute of Japan (AIST, NMIJ) launched a project for the development of AC shunt standards. AC shunts allow the most precise measurement of current. A high‐precision AC shunt is an important component of nonsinusoidal power standards. The AC shunt calibration system helps improve the uncertainty assessments of the national primary power standards. The calibration system design with uncertainties of up to 10 ppm requires a precise buffer amplifier which has uncertainties of up to 1 ppm in the frequency range from 10 Hz to 10 kHz, with other uncertainty components taken care of. The two buffer amplifiers dealt with in this paper were verified to have errors within 2 ppm and uncertainties within 1 ppm in in‐phase and quadrature error in the frequency range from 10 Hz to 10 kHz. This also implies a possibility of reducing both in‐phase and quadrature error at 10 kHz within 1 ppm, by taking advantage of both features. This paper describes the circuit design and evaluation results of two different buffer amplifiers. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 24–31, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21218     

基于FPGA的小数分频频率合成器设计

文中介绍了一种小数分频频率合成器的设计方案。该方案中的分频部分基于FPGA进行设计与实现,仿真结果表明正确。FPGA在设计方案中的应用使得电路简单且便于二次开发。