Electron beam for LHC

A method of delivering a small energy spread electron beam to the LHC interaction points is proposed. In this method, heavy ions are used as carriers of projectile electrons. Acceleration, storage and collision-stability aspects of such a hybrid beam is discussed and a new beam-cooling method is presented. This discussion is followed by a proposal of the Parasitic Ion–Electron collider at LHC (PIE@LHC). The PIE@LHC provides an opportunity, for the present LHC detectors, to enlarge the scope of their research program by including the program of electron–proton and electron–nucleus collisions with minor machine and detector investments.     

LHC: The world's largest vacuum systems being operated at CERN

With the successful circulation of beams in the Large Hadron Collider (LHC), its vacuum system becomes the world's largest vacuum system under operation. This system is composed of 54 km of ultra high vacuum (UHV) for the two circulating beams and about 50 km of insulation vacuum around the cryogenic magnets and the liquid helium transfer lines (QRL). The LHC complex is completed by 7 km of high vacuum transfer lines for the injection of beams from the SPS and their dumping.Over the 54 km of UHV beam vacuum, 48 km are at cryogenic temperature (1.9 K), the remaining 6 km are at ambient temperature and use extensively non-evaporable getter (NEG) coatings, a technology that was born and industrialised at CERN.The cryogenic insulation vacuum systems, less demanding technically, impress by their size and volume: 50 km and 15,000 m³. Once cooled at 1.9 K, the cryopumping allows pressure in the 10⁻⁴ Pa range to be attained.     

First results of the LHC longitudinal density monitor

The Large Hadron Collider (LHC) at CERN is the world's largest particle accelerator. It is designed to accelerate and collide protons or heavy ions up to the center-of-mass energies of 14 TeV.Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, in particular to check the injection quality and to measure the proportion of charge outside the nominally filled bunches during the physics periods. In order to study this so-called ghost charge at levels very much smaller than the main bunches, a longitudinal profile measurement with a very high dynamic range is needed.A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions.A prototype was installed during the 2010 LHC run and was able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 10⁵ to be achieved.First measurements with the LDM are presented here along with an analysis of its performance and an outlook for future upgrades.     

Optimized annular triode ion pump for experimental areas in the LHC

The large hadron collider will be the world next generation accelerator to be operational in 2007 at CERN. The UHV requirements force the installation of ion pumps in the experimental areas of ATLAS. Due to the unacceptable particle background that standards ion pumps may generate, a reduction in the amount of material constitutive of the pump body is required. Hence, a stainless steel 0.8 mm thick body annular triode ion pump has been designed. A pumping speed of ∼20 l/s at 10⁻⁹ mbar is provided by 15 pumping elements. Finite elements analysis and destructive tests have been performed in its design. Final vacuum tests results are shown.     

Bond-slip behavior of self-compacting concrete and vibrated concrete using pull-out and beam tests

This paper analyzes the bond behavior of an innovative construction material, self-compacting concrete (SCC), in comparison to vibrated concrete (VC), using pull-out and beam tests according to the Rilem procedures. The main analyzed parameters were the concrete compressive strength, the steel bar diameter, the concrete type and the test adequacy to provide a value for bond strength. Also, a comparison between Code provisions and empirical equations was done. According to the results, SCC and VC specimens presented similar behavior. The equations results showed a satisfactory approach compared to the experimental ones, but as expected Code provisions were very conservative. Based on the obtained results, it could be concluded that the same parameters adopted for VC can be extended for SCC.     

Development of stress screens

Development of stress screens is discussed including selection of stimuli appropriate to the defect types sought, selection of screen levels and then finally proof of screen tests.     

Industrial leak testing of dangerous goods packagings

The Dangerous Goods Regulations currently do not include limit leakage rates or sensitivity requirements for industrial leak testing procedures that are equivalent to the bubble test, which is the prescribed test method for design type testing of dangerous goods packagings. During series production of such packagings, various methods are used, which often do not meet the requirements of the bubble test with regard to important criteria. Sensitivity, flow direction, pressure level and automatability are particularly important factors when selecting a suitable industrial leak testing method. The following methods are in principle both suitable and equally effective as the bubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detection and gas detection methods (pressure technique by accumulation and vacuum chamber technique). To ensure a uniform test level during design type testing and production line leak testing and therefore a comparable safety level as required by the Dangerous Goods Regulations, it is necessary to include a more precise specification in these regulations. This requires, on the one hand, information about the sensitivity of the bubble test and, on the other hand, the inclusion of a list of suitable, equally effective industrial test methods with their specific boundary conditions.     

基于PLC和组态王的真空检漏回收装置监控

为实现电冰箱整机、空调器及蒸发器和冷凝器等部件在流水线上焊接工序后进行快速检漏和氦气的循环利用,研发了真空检漏回收装置监控系统.该系统采用上下位机控制模式,上位机采用工控机+组态软件,下位机采用OMRON中型CQMIH,充分发挥各自优势,实现了真空检漏回收装置的监控.实际运行表明,系统最小可检漏率达到1×10-3Pa·m3/s,氦气回收率不低于97％.     

比对法漏率校准装置

比对法漏率校准装置是计量气体漏率的一种装置 ,可绝对法和相对法对真空漏孔进行校准。绝对法的校准范围为 10 - 4～ 10 - 9Pa· m3/s;相对合成标淮不确定度为小于 10 %。相对比对法的校准范围为 10 - 6～10 - 1 0 Pa· m3/s,相对合成标准不确定度为小于 2 5 %。     

ZQJ-291检漏仪在真空检漏设备数据采集系统中的应用

通过对检漏仪的通讯原理的分析,介绍了 ZQJ-291检漏仪在真空检漏设备数据采集系统中的应用.针对提高真空检漏设备的自动化水平的目标,详细阐述了ZQJ-291检漏仪终端软件的开发思路及关键功能的实现,在文章的最后对软件界面进行了展示.     

Outgassing measurement of an LHC collimator and estimation for the NEG performances

The outgassing rate of the collimators in the Large Hadron Collider (LHC) at CERN has an important role for the life-time of the Non-Evaporable Getter (NEG), and an accurate analysis allows the definition of future activities, like NEG vacuum activation. For these reasons, both, total outgassing rate and gas composition of a secondary collimator have been measured in the laboratory. The outgassing rate decreases by about two orders of magnitude by after bake-out and moreover, repeated bake-out further reduced the outgassing rate. The gas transmission through the NEG coated beam pipes and the resulting pressure distributions near the collimator were also measured in a dedicated setup. It is found that the main gas component after just 2 m of NEG coated beam pipe is CH₄ due to the extreme pumping speed of NEG for the other gases. Large amount of outgassing for H₂ and carbon related molecules are released when moving the collimator jaws. It is found that the NEG is very effective even in such case with large gas load.     

超声波技术在检测真空系统泄漏中的应用

基于电厂真空系统泄漏是一种常见故障,因此研究一种简便、快捷、准确的检测方法是必要的.运用超声波技术研究了检测真空系统泄漏的新方法.实践表明,该方法是可行的.所给出的应用超声波技术检测真空系统泄漏的原理和检测方法是有效的.     

航天器单机产品真空室检漏法测量结果的不确定度评定

航天器推进系统的单机产品的漏率测试往往采用氦质谱真空室检漏法,研究该方法测量结果的不确定度评定具有重要的工程应用价值。本文首先对真空室检漏法的原理进行了分析探讨,并从不确定的基础理论出发系统地研究了氦质谱真空室检漏法测量结果的不确定度评定方法,并结合工作的具体案例给出了评价的具体步骤。     

Reduction of heat leak in cryogenic system using Peltier current leads

Peltier current leads (PCLs) for cryogenic systems are investigated in regard to temperature dependence of thermoelectric materials. Due to the Peltier effect on the thermoelectric parts of the current lead, PCLs act as heat pumps. It is expected that PCLs will reduce the amount of heat leak from the room temperature side to the low temperature side of a cryogenic system. Six (three each for p and n type) hot-pressed BiTe samples for PCLs are selected to estimate PCL performance. Our experimental results and analyses indicate that PCLs show a capacity in the order of several hundred Amperes and as much as 20-30% reductions of heat leak.     

管道泄漏检测新方法研究

为提高管道泄漏检测的准确度、降低漏报率,提出一种基于负压波多压力传感器管道泄漏检测的新方法.该方法依据泵站前后端的所有压力传感器接收减压波的先后顺序,综合判断减压波是由管道泄漏引起还是由泵站工况波动调整引起;并且根据不同状况下各个压力传感器测试点检测到压力变化各不相同,从而确定故障性质和故障点.仿真实验表明:该方法不仅能降低系统漏报和误报率,而且能够提高系统泄漏点的定位准确度.     

电火花检漏仪的校准

针对国内电火花检漏仪无国家检定规程或校准规范可依据的现状,探讨该类设备的校准方法以及校准参数的选择。基于电火花检漏仪的工作原理及计量特性,从校准的准备、校准项目、校准方法及对标准器的要求展开论述,提出不同类型电火花检漏仪校准项目及校准方法的异同,形成一套系统地科学地校准方案。实验表明,校准方法可靠,有良好的可操作性和溯源性,为电火花检漏仪的现场工作提供保证。     

真空粉末绝热容器检漏方法之探讨

以我国批量生产真空粉末绝热容器的实际情况为例,并通过数据计算分析,认为对真空粉末绝热容器可以用静态升压法考核夹层总气载,再结合分子筛的吸附作用来满足容器使用寿命的要求。目前,这种方法广泛地运用于真空粉末绝热容器制造业。     

四极质谱计在真空检漏中的应用

介绍了使用四极质谱计进行真空检漏的原理和方法,分别对超高和极高真空系统做了检漏实验研究，并取到了满意的结果。四极质谱计检漏有检漏仪检漏无法比拟的优点，适合在真空工程中推广应用。     

球罐区氧气管道泄漏应对措施及检修处理

安钢制氧厂球罐区氧气管道泄漏,影响了正常供氧并威胁安全生产。文章详细介绍了氧气管道泄漏的应对措施以及检修过程中的停送气方案、施工方案和安全措施,彻底消除了泄漏隐患。     

航天器氦质谱真空容器总漏率检测的灵敏度及可信度探讨

依据航天器氦质谱真空容器总漏率检测原理,讨论了检漏仪和真空容器直接相连、同真空容器主真空泵并联、在前级泵和主真空泵间等连接方式,逐项研究了总漏率测试的最小可检漏率、反应时间,分析各种连接方式的应用特点,认为对大型航天器氦质谱真空容器检漏系统,检漏仪连接在前级泵和主泵之间可得到较好的灵敏度和反应时间.通过测量不确定度的分析与评定,确定一般航天器氦质谱真空容器总漏率检测的相对标准不确定度小于10％.