乳状液电磁场破乳法的研究

提出了一种利用电磁感应原理产生涡旋电场进行破乳的新方法。将螺线管、磁芯构成的电感器与电容器串联组成Ｌ－Ｃ谐振电路。在此电路中通过高频电流，使其在破乳器内产生高频磁场，从而感生出高频涡旋电场。在此电场的作用下，乳状液滴极化并加速其运动与碰撞，达到破乳的目的。该法在输入信号电压约３００Ｖ、电流几＋ｍＡ、频率２０ｋＨｚ的条件下，可感应出强度为几十＋ｋＶ／ｃｍ的涡旋电场，５ｍｉｎ内静态破乳率大于９８％。在     

On the limit of superheat of cryogenic liquids

In an effort to test the empirical law governing the scaled superheat-limit,¹ we measured superheated neon and hydrogen with special emphasis on the critical superheat. Experimental results were compared with a Döring-Zeldovich-like nucleation theory and satisfactory agreement was found. Some deviation from the corresponding states of the scaled superheat-limit for classical fluids was apparent, thought to be caused by quantum effects on surface tension, and are appreciable for neon and hydrogen.     

Effect of an electric field on the oxidation of aluminium at room temperature

Effect of an applied electric field on the oxidation rate of vacuum deposited aluminium thin films were studied at room temperature in the laboratory atmosphere. Above the critical field, a negative potential applied to the film enhanced the rate of oxidation, while a positive field retarded the rate. This suggests an oxidation mechanism involving cationic diffusion. The observed change in the rate of oxidation for an applied field agrees with the Mott-Cabrera theory.     

无电流电场沉积CdS纳米薄膜

针对普通电沉积制备纳米薄膜工艺中的电极析气、电解、电镀等有害电极反应对沉积过程和沉积膜造成不良影响的问题,提出了一种待沉积薄膜的基材及其上的沉积膜不与沉积电路组成闭合电流回路的电场沉积装置及电场沉积制备纳米薄膜的新方法.在自制的电场沉积装置上制备了CdS薄膜并用AFM表征了薄膜微观结构.获得了粒径约30nm的CdS微粒致密平整薄膜.研究结果表明,新方法具有薄膜质量好、无需使用贵金属电极、沉积速度快等优点.     

电场固溶处理对1420铝锂合金组织和性能的影响

研究了电场固溶处理对１４２０铝锂合金组织和性能的影响。试验结果表明,电场固溶处理可以提高１４２０铝锂合金时效后的强度,但塑性略有下降;随固溶处理温度的提高,合金的强度提高而塑性降低;固溶处理上同时,随电场强度的提高,合金的强度提高而塑性下降,经电场固溶处理后的试样时效析出的δ＇相更细小弥散;电场的存在有利于抑制亚晶粒的长大。     

碳纳米管冷阴极超高真空鞍场规的电场模拟与实验研究

在静电鞍场规的基础上研制了一种碳纳米管(CNT)冷阴极鞍场规(SFG).这种冷阴极鞍场规具有电极尺寸小,吸放气率低,热效应低,功耗低的特点.本文首先计算了碳纳米管冷阴极鞍场规的电场分布,计算结果表明,二极型碳纳米管电子枪的引出栅极的正电位在低于100 V的情况下对环形阳极鞍场规的轴向电位分布影响很少;并且在现有条件下对规管参数进行了测试,实验测定的规管对空气的灵敏度是1.05 Pa-1,规管功耗由热阴极规的0.9瓦减小到7毫瓦.     

Copper-TFE friction at cryogenic temperatures

Interfaces between metals and polytetrafluoroethylene (TFE) are common in cryogenic systems. In this paper we present results from measurements of the temperature dependence of the dynamic coefficient of friction between commercially pure copper and TFE. The effect of the copper surface finish was also determined. The effects of load and speed were evaluated over a small range, but nearly all data were taken at a surface speed of 5.4 cm s^?1 with a load of 1.63 N cm^?2. These values are typical of those encountered by the moving parts of some cryogenic machinery.     

Testing of strain-gauge pressure transducers up to 3.5 MPa at cryogenic temperatures and in magnetic fields up to 6 T

The characteristics of four commercial strain-gauge pressure transducers suitable for measurements in a temperature range from 4.2 to 293 K were determined in the presence of magnetic fields up to 6 T. The highest pressure measured was 3.5 MPa. Tests showed that if the transducers are used in these conditions and no corrections are made, uncertainties up to 19% of the transducer full scale may be inherent in measurements. When such high error levels are unacceptable, the transducers must be individually calibrated under the working conditions: in this way the uncertainties in pressure measurements can usually be kept below 1 % of the transducer full scale.     

低温推进剂的液位测量

在低温贮罐内贮存液氢、液氧、液氮，液住的精确测量是非常重要的。本文介绍了差压式液位测量方法，经实践应用证明，其结果是比较令人满意的。     

交变电场剥离氧化石墨的研究

化学还原法被认为是实现大规模生产石墨烯的主要途径之一,而剥离氧化石墨为氧化石墨烯是获得高品质石墨烯的关键步骤。采用交变电场剥离氧化石墨,研究了电压U、频率f和电极间距d对剥离结果的影响。结果表明氧化石墨烯的厚度和横向尺寸随着电压的增大而减小,随着频率的增大而增大;在电压能满足剥离效果的前提下,随着电极间距的增大,氧化石墨烯的厚度和横向尺寸呈减小趋势。     

Space charge field effect on light emitting from tetracene field-effect transistor under AC electric field

By applying square wave AC voltage to the Au source electrode of tetracene based field-effect transistor (FET), electroluminescence (EL) was obtained. The results suggest that electrons and holes were injected alternately from the source electrode and recombined each other, and lead to the EL. This type of EL was localized at the interface between the source electrode and tetracene, and enhanced periodically with two relaxation times in accordance with the applied AC voltage cycle. We modeled the carrier behavior in the FET and explained the decay of EL, taking into account the space charge field contribution. Finally, using an AC voltage superposed on DC bias voltage, it was shown that electron injection was prompted only by space charge field.     

A capacitance-graded cryogenic high voltage bushing for vertical or horizontal mounting

The cryogenic high voltage bushing for the terminations of the 138 kV, 4100 A superconducting cable prototype at the Brookhaven National Laboratory (BNL) is described. The bushing is energized with the line-to-ground voltage between the coaxial centre and outer surrounding conductors, in the axial direction there is a temperature difference from ambient to about 6 K.The capacitively graded bushing can be mounted in any position. It is vacuum tight and withstands pressures of more than 20 bar. The heat leak of the insulation body in axial direction is only 8.5 W.The electrical specifications of the bushing are: 825 kV, 1.2 × 50 μs impulse voltage; 240 kV rms ac 2h test voltage: and > 160 kVs partial discharge inception voltage.This bushing concept may easily be modified to meet most conceivable thermal, mechanical and electrical requirements of cryogenic high voltage engineering.     

球形石墨空腔电离室内部电场的研究

国际上辐射剂量计量基标准电离室多采用球形或圆柱型空腔电离室,其腔室自身几何对称。不同形状的收集极置于腔室中,会影响腔室内部的几何对称性,进而对其内部电场的均匀性和电荷的收集产生一定的影响,作为绝对测量需要对电离角响应方向性进行修正。该文采用Ansoft Maxwell 2D程序建立一个石墨空腔电离室灵敏体积内的静电场模型,分别计算含有3种不同形状收集杆腔室内的电势分布;并对同系列大体积电离室收集杆是否产生放电现象进行了分析,对同类型电离室相关指标的优化设计提供一定的参考。     

Measurement of critical temperature as a function of field

The critical temperature has been measured for various magnet conductors as a function of the perpendicular applied magnetic field. The isothermal environment was provided by a variable temperature cryostat which fits into the bore of a 10 telsa solenoid. The temperature gradient across the sample volume was measured to be less than 25 millikelvins. The superconducting to normal state transition was measured resistively, using sample current densities from 0.01 to 2 A cm^?2. The maximum applied magnetic field was 10 T and varied less than 0.5% in the sample volume. The critical transport current range of the samples measured from tens to thousands of amperes in the presence of a 10 T perpendicular magnetic field at 4.2 K.     

工频电场测量仪的校准装置

针对目前国内还没有在环境监测中广泛使用的对工频电场探头进行计量的检定规程或者校准规范,设计了一套工频电场探头校准装置,根据理论推导,确定所产生标准电场强度。通过高压源控制器来控制升压实现高压输出。校准所采用的电板满足所有工频电场测量仪校准需求,产生的电场强度范围从10 V/m到100 kV/m。最后,对溯源后的HI-3604分别进行电场强度测试与分析,实验数据表明:该校准装置可以用于工频电场探头校准,并给出了校准不确定度。     

Equipment for long-term creep testing at cryogenic temperatures

Equipment and procedures for long-term cryogenic creep testing are presented in detail. Particular attention was given to the maintaining of constant cryogenic test temperature and with respect to the stability and sensitivity of strain measurements. Typical long-term cryogenic creep testing results on oxygen free high conductivity (OFHC) copper are presented.     

Creep of copper at cryogenic temperatures

The long-term creep behaviour of OFHC copper was investigated at 4.2 K and 77 K. At 77 K, steady-state creep was observed and the creep rates were tens of orders of magnitude higher than would be expected from extrapolations of ambient temperature creep data. The stress exponent obtained at 77 K is 2.2. The apparent activation energy at 77–90 K range is about 0.02 eV. At 4.2 K, transient creep was observed. TEM study of all crept specimens showed cell structures in support of the occurrence of substantial creep at cryogenic temperatures.     

Spacecraft borne long life cryogenic refrigeration status and trends

The status of cryogenic refrigerator development intended for, or possibly applicable to, long life spacecraft borne application is reviewed. Based on these efforts, the general development trends are identified. Using currently projected technology needs, the various trends are compared and evaluated. The linear drive, non-contacting bearing Stirling cycle refrigerator concept appears to be the best current approach that will meet the technology projection requirements for spacecraft borne cryogenic refrigerators. However, a multiple redundant set of lightweight, moderate life, moderate reliability Stirling cycle cryogenic refrigerators using high-speed linear drive and sliding contact bearings may possibly suffice.     

稳恒电场对小晶面晶体生长的影响

本文选用NH4Cl和H2O过饱和二元溶体为研究对象,研究其在稳恒电场作用下溶体中游离晶的重熔规律及晶体生长规律.利用显微镜感光器件(CCD)及智能通讯测温仪表,对实验过程进行实时照片拍摄和实时温度记录.结果表明:电场的Joule Heat效应为决定性因素,使得NH4Cl溶体温度场显著变化,导致糊状区的游离晶重熔明显;N...     

微型大气电场监测装置的设计与实现

针对户外场磨式地面电场仪存在的输入阻抗高、感应电流信号弱、易受外界电磁波干扰、功耗大且无市电供电等问题,设计一种光伏发电加蓄电池储能供电的低功耗大气电场监测装置.为减小系统功耗,提高测量精度,设计微型低速双定子差分式电场传感器,传感器感应到的两路微弱电流信号经过T型反馈网络实现I/U变换.通过减法器和4 Hz低通滤波器...