DL-6A型电阻真空计的误差

本文介绍DL-6A型电阻真空计的误差。DL-6A型电阻真空计测量范围是10-1~105 Pa,在10~5×103 Pa,误差为10%,在小于10 Pa和大于5×103 Pa误差为35%。     

A Pirani gauge in a high-intensity proton accelerator

We have developed a Pirani-type vacuum gauge for monitoring the back pressure of a turbo-molecular pump (TMP), which is employed as the main pump for the 3-GeV Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Complex (J-PARC).As vacuum components are subjected to high levels of radiation in these devices, the TMP and the vacuum gauge used for monitoring the TMP’s back pressure should have high reliability and a long life so as to minimize exposure to radiation during maintenance. Moreover, to ascertain the vacuum conditions of the ring and to monitor the back pressure, the gauge should preferably be capable of measuring pressures from 0.1 Pa to 10³ Pa. To satisfy these requirements, the following measures were taken: All the components around the sensor head, including the connector and cables, were replaced with components that were guaranteed to perform satisfactorily even with a radiation dose greater than 30 MGy. Then, the semiconductor devices used in the measuring circuits were checked by using the four-point probe method and found to work satisfactorily at a distance of 150 m from the sensor. To measure higher pressures, the current control circuit was modified in such a way that the set value of the current increased in stages as the pressure increased. Further, it was ensured that the gauge showed high resistance to vibration and to an abrupt air intake as well as high radioactive resistance. The newly designed gauge head comprised a series of twelve Pt wires, each with a diameter of 100 μm. It was confirmed that pressures from 5 × 10⁻² Pa to atmospheric pressure were measurable with an accuracy of less than 30%.This Pt Pirani gauge has shown good performance in monitoring the back pressure of the TMP at the J-PARC RCS, where it has been in use since Oct. 2009.     

低温绝热容器中皮拉尼真空计取代热偶真空计的可行性分析

在低温绝热容器夹层真空度的测量中,皮拉尼真空计和热偶真空计较适用,目前热偶真空计应用较多。从测量范围、测量精度、测量温度、互换性、远程监控、检漏能力和性价比等方面,对皮拉尼真空计和热偶真空计的性能进行了比较,得出皮拉尼真空计更适用于低温绝热容器夹层真空度测量的结论。最后列举了目前国外几种典型的商用皮拉尼真空计和热偶真空计的技术参数。     

A design for an immersable pressure-capacitance gauge

An immersable pressure-capacitance gauge has been designed which has a linearity over a pressure range, is non-magnetic and has twice the sensitivity of a single diaphragm     

Inverted forms of the new helium vapour pressure equations

Equations relating the vapour pressures of He³ and He⁴ to temperature on the ‘Échelle Provisoire de Température de 1976’ have been approved by the Comité International des Poids et Mesures. Using these definitive equations temperatures can only be calculated from measured pressures by iteration. Moreover, the equations are not amenable for use at less than full precision. Alternative equations expressing temperature as a function of pressure over somewhat reduced ranges are now presented in forms which are more easily solved for temperature and are capable of further simplification if reduced accuracy is acceptable.     

压力表自动检定仪的设计

利用单片机、步进电机驱动器、步进电机为主要硬件,构建压力表自动检定装置。根据检定规程要求,由单片机控制造压系统,由键盘设置压力点,实现检定过程自动化。装置自动采集标准压力值,自动计算示值误差、回程变差、轻敲位移。保存检定数据、打印检定结果。     

强磁场下铑铁温度计的磁致电阻效应研究

以铑铁温度计为研究对象,研究了其在0-16 T磁场下、2-300 K温区内的磁致电阻效应.结果表明:铑铁温度计在0-16 T场强下,2-77 K温区内磁效应随场强的增强和温度的降低而明显升高,77-300 K温区内温度计受磁场的影响较小,其中在16 T、2 K处,以及16 T、300 K处的磁效应分别为70.94%和-...     

Direct pneumatic pressure in a clamping technique during strain gauge bonding

A technique is described for the clamping of metallic foil strain gauges during epoxy adhesion bonding to non -porous surfaces. Following application of the uncured adhesive, the gauge is conformed to the surface using self-adhesive tape and the workpiece placed in a pressurised environment for the duration of cure. The pnematically derived clamping pressure is transmitted directly to the glue line, and is equal to the pressure within the containment vessel. Since the clamping pressure is both uniform over the strain gauge area, and readily reproducible between installations, it is possible to produce consistent gauge performance. The technique may offer time and cost advantages over classical clamping methods where gauges are installed on small, intricate, or batch components in stress analysis and transducer applications.     

Thick film resistors in low-temperature resistance thermometry in high magnetic fields

Thick film resistors exhibit a strong dependence on temperature in the cryogenic range below 20 K. In this range the temperature coefficient of resistance is estimated to be comparable to that of commonly used resistance thermometers.The resistance change by the action of the magnetic field is observed to be only small and independent of magnetic field direction. By using these resistors in cryogenic resistance thermometry in intense magnetic field the temperature error due to the magnetoresistance is shown to be only small in comparison with frequently used sensors.According to these results thick film resistors are reported to offer an interesting alternative in cryogenic resistance thermometry within intense magnetic fields.     

Absolute measurements of ultrasonic pressure by using high magnetic fields

A hydrophone is introduced that exploits the emf signal generated in a conductor when sonicated in the presence of a uniform static magnetic field. The method uses a small metal coil or metal membrane as a hydrophone receiver. Acoustic signals at 748 kHz are introduced in 1.5 T and 4.7 T fields and recorded both through direct electrical contact with the hydrophone and via RF pick-up coils, allowing wireless placement of the hydrophone. Linear response Is confirmed over four orders of magnitude in the pressure amplitude. Waveforms determined from the detected voltage are shown to be in excellent agreement with those obtained using a calibrated polyvinylidene difluoride film, and absolute values correlate within 20%. The methods are conceptually suitable for use in the presence of the high and uniform field of commercial MR scanners. The hydrophone may appear particularly useful as a quality assurance device in therapeutic and diagnostic acoustic techniques that use MRI.     

指针式压力表自动计量校准系统

目前,指针式压力表常采用影像法进行计量校准,但在计量过程中存在压力表指针难分割、背景难分离和识别准确率低等问题,为解决上述问题,结合不同规格压力表表盘的外观尺寸,对压力表自动计量校准系统进行研究。首先,根据工业相机视野范围内压力表表盘外形尺寸,自动判断相机与压力表之间最佳工作距离;其次,利用图像边缘梯度值评价图像清晰度,自动完成相机对焦;最后,采用极坐标转换方法实现刻度线定位、指针提取、实时读数等功能。测试结果表明,该系统适用于外壳直径为40,60,100,150,200,250 mm的指针式压力表计量校准。     

On the possible use of a commercial Penning gauge as a magnetic field sensor

Penning sensors were originally conceived to extend the measurement range of cold-cathode gauges in the direction of low pressures by introducing an additional constant magnetic field. This paper examines the possibility of using a commercially available sensor to measure magnetic field by keeping pressure constant. For the preliminary tests reported, a commercial Penning gauge was exposed to magnetic fields in the range of a few tens of mT to 1.1 T. Three different regimes were identified. In the first, up to 150 mT, the measured current increases linearly with the applied magnetic field. Following a very irregular transition region of the order of 50 mT, for fields between 200 mT and 1.1 T, the measured current decays relatively smoothly. The results suggest that the principle may be applicable for the measurement of steady-state fields in harsh environments, with high temperature and neutron fluence.     

On the stability of carbon glass thermometers cycled at low temperatures under high magnetic fields

We report on the reliability of three carbon glass thermometers used in the temperature range 4.2 K – 50 K under high magnetic field conditions.In two of the three sensors we observed a serious lack of reproducibility (1.5 K at 25 K). These results indicate that in experiments requiring precise temperature measurements in the range 20 – 30 K, it is necessary to perform regular calibrations of carbon glass thermometers versus secondary standards such as platinum or germanium resistors.     

Acoustic thermometry in gases using pulse techniques

This paper presents a guide to acoustic thermometry in gases using pulse techniques. The dependence of the measured acoustic velocity on gas properties, temperature, pressure and flow is described. These relationships are used to assess the characteristics of the thermometer, and the basic arrangement of the thermometer is described. The performance of the thermometer is dependent on the transmission characteristics of the gas; these are described together with the effect they have on pulse timing. The Stirling engine application is used to illustrate the above and other possible applications are briefly discussed.     

Vapour pressure measurements on 1,1,1,2-tetrafluoroethane (R134a) from 180 to 350 K

Measurements of vapour pressures were made for 1,1,1,2-tetrafluoroethane (R134a) from 180 to 350 K by using a static cell. Temperatures were measured with a platinum resistance thermometer to within an accuracy of ±0.03 K. Pressures were measured with calibrated oscillating quartz-crystal pressure transducers with uncertainties estimated to range from 0.02 to 1.8 kPa.     

压力表机构参数优化设计

本文主要介绍弹簧管压力表中曲柄滑块机构参数的优化设计方法，讨论了优化设计的数学模型以及用计算机求解的方法．     

The observation of resistance oscillations in metals at high magnetic fields using a SQUID

Quantum oscillatory effects provide particularly unambiguous information about the properties of quasiparticles in metals, and have consequently been used for the purpose of understanding the low temperature behaviour of a wide variety of metallic elements and compounds, including the recently discovered heavy fermion materials. Unfortunately, the signals which are produced by these oscillations are often so weak as to be undetectable, because of the high effective masses of the quasiparticles, or the presence of imperfections in the samples, or otherwise. In order to improve our ability to measure these effects, the author has developed a system for the detection of resistance oscillations which uses a SQUID as the amplifying element and which fits inside a toploading dilution refrigerator probe. It has proven possible to use this instrument to investigate very elusive phenomena in samples which have been cooled to 0.02 K in magnetic fields of 13.7 tesla. For example, although no resistance oscillations have previously been seen in aluminum, except under conditions of magnetic breakdown, the new system has made it possible to detect resistance oscillations in this material under relatively arbitrary conditions. In the case of the heavy fermion compound CeRu₂Si₂, oscillations of 10^–9 have been detected against a background resistance of about 10^–5 , using excitation currents of around 10^–2 A.     

压力表对液压千斤顶检定示值的影响分析

压力表作为液压千斤顶的关键性指示计量器具，其计量性能的优劣，直接影响到建设工程桩基承载力和工程结构预应力的力值测量结果的准确性。为解决这一问题，本文重点探讨了压力表测量范围、准确度等级、分辩力和配套检定等对液压千斤顶检定结果的影响，澄清了生产厂家和施工单位在液压千斤顶使用中的一些习惯误区，并在试验验证基础上给出了不确定度分析和合理化建议。     

Dynamic pressure measurements during pulsed gas injection in a quadrupole ion trap

A quadrupole ion trap has been modified to perform dynamic pressure measurements during pulsed introduction of gases. A continuous electron beam is directed through the ion trap where the gas is ionized via electron impact. Ion and electron currents are monitored on the ring and end-cap electrodes, respectively. Dynamic pressure measurements in a region not accessible to a standard gauge are performed using a static quadrupole field. Characteristic current-voltage curves of the ion-trap gauge are presented and optimum operating conditions of the electron-ion optical system are identified in steady state conditions. The sensitivity of the ion-trap gauge is calibrated at these optimum conditions. In the pulsed gas mode ion and electron signals are measured simultaneously on a fast oscilloscope. The time constant of the circuit for the dynamic measurements is ∼129 μs and pressure variations of ∼10⁻⁴-1 Pa occur within 60-130 ms. The exponential decay of the ion signals is used to calculate pumping speeds for helium and argon gases. The distinctive advantages of pulsed gas injections over the use of static pressures in quadrupole ion-trap mass spectrometry are emphasized.