Comparison of quantized Hall resistances RH(2) andRH(4) of a GaAs/AlGaAs heterostructure device

Quantized Hall resistances R_H(4) and R_H(2) of a GaAs/AlGaAs heterostructure were compared with reference resistors whose values are close to h/4e² or h/2e². The values of the reference resistors were compared with a 100 ohm standard resistor via a cryogenic current comparator (CCC) resistance bridge. Results showed that (4×R_H(4)-2×R_H(2))/2×R_H (2)=(0.037±0.019)×10^-6     

中国一级标准海水不确定度分析研究

中国一级标准海水作为有证标准物质,不确定度是其一项重要的质量参考指标。参考了国际标准海水(IAPSO SSW)不确定度的分析方法,引入GB/T 15000.3《标准样品工作导则(3)-标准样品定值的一般原则和统计方法》等标准中相关的统计方法,对定值不确定度、均匀性不确定度、长期稳定性不确定度3个分量进行了逐一分析。以P1批次一级标准海水的数据为例,计算得出以上分量的电导率比不确定度分别为5.00×10^-6、 5.05×10^-6、 4.50×10^-6,合成标准不确定度为8.42×10^-6,扩展不确定度为1.7×10^-5。依据不确定度传播规律,计算得出盐度扩展不确定度为6.6×10^-4(或0.001)。     

Upscaling DC resistance using a Josephson junction array

A ratio standard for DC resistance measurements in the range above about 10 kΩ using a three-terminal Josephson junction series array is described. Resistance ratios of two-terminal resistors from 1:1 to at least 1:10 are examined with a single device utilizing the voltage steps of the Josephson array as voltage sources of a potentiometer bridge configuration. Some features of the circuit are discussed. The system promises systematic ratio errors below 10^-8 and uncertainties which depend only on the quality of the resistors. Preliminary measurements with a prototype instrument show a relative reproducibility of 1×10^-7, limited by the noise of a commercial digital multimeter used as a detector     

基于任意波形发生器的高压短路试验测量系统校准方法和装置的研究

提出了一种将标准短路试验波形注入多通道任意波形发生器,来产生模拟实际的校准波形,进而对测量系统进行校准的方法。校准装置使用现场可编程门阵列(FPGA)、直接数字频率合成器(DDS)等器件。对装置的检定结果表明:在10 Hz^200 kHz频率范围内,输出频率、输出电压最大误差分别为2.1×10^-6、3×10^-3。重复输出10次,输出幅值的最大相对标准偏差为5.7×10^-4,1年内幅值变化的最大相对标准偏差为1.9×10^-4。通过将该装置用于实际高压短路试验测试系统的校准,验证了试验波形的噪声、零漂及带宽均会对测量系统的准确度产生显著影响。     

一种脉宽调制的高稳定连续可调直流电压源

介绍了一种以深埋齐纳电压基准元件LTZ1000A主电路为基础,结合脉宽调制技术实现的在0～10 V范围内连续可调的高稳定直流电压源。选用精密电阻并采用适当的保温与隔离措施,实现了电压基准主电路输出高稳定7 V电压,其短期稳定性达到1.7×10^-8。利用具有相同温度系数和阻值的精密电阻组成比例升压电阻网络,使输出10 V电压的短期稳定性为2.4×10^-8。同时利用脉宽调制并经DC-DC转换电路及滤波电路得到0～10 V的电压输出,短期稳定性可在10^-7量级左右。     

A 100000-A high precision on-site measurement calibration devicefor heavy direct current

A 100000-A, high precision device of the magnetic modulation current comparator type, which can be used in industrial heavy direct current systems for online calibration and measurement, is presented. Testing of the comparator indicates that its current ratio accuracy is 5×10^-5, and that measurements of voltage with a standard resistor achieve an accuracy of 5×10^-4. These are slightly degraded to 3×10^-4 for on-site calibration and 1×10^-3 for on-site measurement. The device, which has a toroidal configuration, can be opened for each installation on a busbar, with a variation in accuracy of less than 2×10^-5. Its magnetic shielding renders it insensitive to magnetic fields up to 1×10^-2 Tea. Its accuracy is better by a factor of two than that of similar industrial measuring devices. The principle of operation and the characteristics of the comparator, the double shielded design, and an analysis of its errors are discussed     

Absolute voltage amplification using dynamic feedback control

A new principle of voltage amplification that is insensitive to drift and aging effects of the feedback resistors is presented. The effect of mismatch of these resistors is reduced to a second-order effect which results in a total gain error of less than 5×10^-6 without the need for any calibration. Moreover, the long-term stability of the whole amplifier is guaranteed by the design when used as a chopper amplifier     

A new low-field determination of the proton gyromagnetic ratio inwater

The proton gyromagnetic ratio in water has been measured by the low field method using atomic magnetic resonance in ⁴He, a multicurrent solenoid and an induction method for the dimensional measurement of the solenoid. The result for air and vacuum environment is γ'_p (low, air)=2.67515451×10⁸ s^-1 T^-1 (0.18×10^-6), γ'_p (low, vacuum)=2.67515418×10⁸ s^-1 T^-1 (0.18×10^-6), based on the adopted values K_J-90=483597.9 GHz/V, R_K-90=25812.807 Ω, and measured values γ(⁴ He)/γ'_p=658.200556, γ(⁴He) (air)=1760.78819×10⁸ s^-1 T^-1 (0.18×10^-6), K_J-90, R_K-90     

Determination of the tesla-to-ampere ratio for the KRISS/VNIIMγ'P-experiment

Tesla-to-ampere ratio giving the largest error in the γ'_P-low-field-experiment has been determined using a modified noncontacting method. The total uncertainty of 0.164×10 ^-6 has been attained. The constant of a solenoid and the γ'_P-value have been corrected for magnetic susceptibility of air. The result is γ'_P=2.675 154 18×10⁸ s^-1 T^-1 (Tesla BI-90) with the total uncertainty of 0.18×10^-6     

毫米波功率计量标准器芯片的研制

针对毫米波WR-6波段功率标准器核心芯片需求,设计了芯片整体结构,研究了结构中各层的微加工工艺,制备了温度传感用Pt薄膜,在250 ℃退火后,100 nm Pt薄膜的电阻温度系数(TCR)达到2.4×10^-3/K,相对稳定度为2.4×10^-6。安装在毫米波功率标准器上的芯片对110～170 GHz的反射率低于-23 dB。直流功率灵敏度为0.83 mΩ/mW。     

光腔衰荡光谱法测定气体中微痕量水不确定度评估

介绍了基于光腔衰荡光谱法测定气体中的微量水的方法原理,该方法适用于含量为0.2×10^-9～20×10^-6 mol/mol的所有气体中水分的测定。建立了光谱分析法的原始数学模型,对测定方法的不确定度进行了评估,结果表明该方法的扩展不确定度为（8～20）×10^-9 mol/mol（k=2,p=95%）。     

Determination of the time-dependence of ΩNBS usingthe quantized Hall resistance

The quantum Hall effect is being used to monitor the US legal representation of the ohm, or as-maintained ohm, Ω_NBS. Measurements have been made on a regular basis since August 1983. Individual transfers between the quantized Hall resistance R _H and the five 1-Ω resistors which comprise Ω_NBS can be made with a total of one standard deviation (1σ) uncertainty of ±0.014 p.p.m. This uncertainty is the root-sum-square of 32 individual components. The time-dependent expression for R_H in terms of Ω_NBS is: R_H=25812.8[1+(1.842±0.012)×10^-6 =(0.0529±0.0040)(t-0.7785)×10^-6 /year] Ω_NBS, where t is measured in years from January 1, 1987. The value of Ω_NBS is, therefore, decreasing at the rate of (0.0529±0.0040) p.p.m./year     

Very high Q microwave spectroscopy on trapped171Yb+ ions: application as a frequency standard

A microwave frequency standard based on buffer-gas cooled ¹⁷¹ Yb⁺ ions confined in a linear Paul trap has been demonstrated in prototype form. The standard exhibits a fractional frequency instability characterized by an Allan deviation σ_y (τ)=3.7×10^-13τ^-1/2 for τ<3000 s. Microwave Ramsey fringes with a Q factor of 1.5×10¹³ have been observed     

一种基于三端口网络的互感器电压串联加法

1954年Zin E和Forger K成功研究出互感器串并联电压加法线路;1988年国家高电压计量站成功研究出互感器双边串联电压加法线路,2006年使用串联型电压互感器进行双边电压加法,2008年试验电压达到1 000/√3 kV,电压比不确定度不大于4×10-5(P=95％).要进一步减小电压比的不确定度,需要最大限...     

Hg+ trapped ion standard with the superconducting cavitymaser oscillator

The frequency stability of an atomic standard based on ¹⁹⁹ Hg⁺ ions confined in a hybrid RF/DC linear trap is described. The 40.5-GHz clock transition has been measured to be 17 mHz wide, representing a quality factor greater than 2×10¹². A 160-mHz line is used to steer the output of a 5-MHz crystal oscillator to obtain a stability of 2×10^-15 for 24000-s averaging times. In a separate measurement, a 37-mHz line is used to steer the output of the superconducting cavity maser oscillator to reach 1×10^-15 stability at 10000 s     

结构化增韧层增韧RTM复合材料预成型体的渗透特性

选用尼龙无纺布(Polyamide Nonwoven Fabric,PNF)作为结构化增韧层,研究了增韧层的引入对纤维预成型体在树脂传递模塑成型(RTM)工艺过程中渗透特性的影响。结果表明:在径向非饱和流动模式下,层间增韧预成型体沿纤维方向的渗透率为5.2×10-12 m2,略低于非增韧预成型体的7.1×10-12 m2,而沿垂直于纤维方向的渗透率为2.3×10-12 m2,略高于非增韧预成型体的1.6×10-12 m2。此外,层间增韧预成型体的单向饱和流动渗透率为2.6×10-12 m2,较非增韧预成型体的1.9×10-11 m2下降了约1个数量级,z向饱和流动渗透率较非增韧预成型体的1.3×10-13 m2下降至2.5×10-14 m2,同样下降了约1个数量级。对复合材料层间微观形貌的分析结果表明:造成预成型体渗透率下降的主要原因首先是PNF引入至层间之后将阻碍层间树脂的快速流动,同时增韧层将使层内纤维含量明显升高,由55.3vol%上升到63.7vol%。     

锁相环路对氢原子钟性能影响的实验分析

实验以上海天文台SOHM-4型氢原子钟脉泽信号和新研制的模拟-数字混合型锁相环路为基础,主要分析锁相环路参数对氢原子钟输出信号的短期频率稳定度和单边带相位噪声的影响。针对氢脉泽信号高Q值的特殊性,通过理论分析和实验验证寻求与其相匹配的最佳环路参数。实验结果表明,锁相环路的参数设置直接影响到氢原子钟输出信号的性能;在脉泽信号不变的情况下,改进后的锁相环路和主电子学系统可使氢原子钟的频率稳定度提高至1.7×10^-13/1s, 3.3×10^-14/10s, 9.1×10^-15/100s, 2.9×10^-15/1 000s, 1.4×10^-15/10000s,即较之原有的技术指标,在各取样时间范围内,频率稳定度的测试结果均提高了半个量级。     

Precision measurement of the atomic mass of 6Li using aPenning ion trap mass spectrometer

We have used a cryogenic (4 K) Penning ion trap mass spectrometer to measure the mass ratios of ⁶Li⁺/¹²C ²⁺, ⁶Li⁺/D₃⁺, and D₂⁺/He⁺. We developed techniques to create ions outside of the cryogenic trap environment and to transport them into the trap where a small number (1-10) were confined. The ions' frequencies of oscillation were measured using a high-Q tuned circuit to detect image currents induced in the trap electrodes. The measurements involving ⁶Li⁺ result in a value for the atomic mass of ⁶Li of 6.015 122 795(16) u, with a fractional uncertainty of ±2.7×10^-9 representing a factor of 30 improvement over the published, tabulated value. A measurement of the D₂⁺/He⁺ mass ratio has an uncertainty of ±1.1×10^-9 and is within 0.6×10^-9 of the tabulated value, thus demonstrating that our techniques are reliable     

1000V多盘感应分压器标准建立

中国计量科学研究院研制了一台1000V多盘感应分压器标准装置,用作工频1000V电压比例标准。该装置使用了一种基于互感器注入的误差补偿技术,可准确提供从1×10^-8到1的宽范围比例出。感应分压器的误差校验使用了包含三同轴屏蔽技术的改进型参考电势增量法,并设计了多比例参考互感器以便对感应分压器进行整体校验。所研制的感应分压器准确度优于1×10^-7,校准结果不确定度小于2×10^-8。