EAST托卡马克装置外冷屏的热负荷分析

外真空杜瓦冷屏 (简称外冷屏 )是 EAST超导托卡马克核聚变装置的重要部件之一 ,它在处于室温下的外真空杜瓦与运行在 4 .5 K温度下的超导线圈之间形成了一道隔热的屏障 ,以保证装置能够稳定高效的运行。文中运用有限元分析软件 ANSYS对外冷屏封头、中筒、底座的传热情况做了计算与分析 ,以得到在氦气入口处压强为 5 .2 bar,温度为 80 K的情况下 ,外冷屏低温面板的详细设计方案     

超导可控电抗器低温系统冷却管道设计

35k V超导可控电抗器工作在70K温区和交流工况下时,由于交流损耗和杜瓦漏热等因素影响,超导双饼端部及杜瓦内壁会产生温升,引起局部失超。文中对超导可控电抗器使用低温过冷液氮冷却进行了分析,调节冷却液流量,改变冷却管道分布和冷却液入口温度,进行了冷却效果的对比分析。仿真结果表明,增大冷却液流量、均匀分布冷却管道和降低冷却液入口温度能够降低杜瓦内温升。     

CAEP FEL-THz 2K氦低温系统建设及其试运行

中国工程物理研究院高平均功率太赫兹大型科研装置(CAEP FEL-THz)采用1.3GHz超导加速器,低温系统为超导加速器提供2K低温环境。低温系统于2016年上半年顺利完成试运行,具备160L/h@4.5K的液氦生产能力和优于66W@2K的冷量能力,保障了超导加速器正常稳定运行所必需的低温环境。据此,简要总结了2K氦低温系统的建设进展,并介绍了低温系统的试运行情况。     

超导低温垂测2K系统设计

为了检验加速器驱动次临界系统直线加速器中的超导腔性能,需要在超导腔装入低温恒温器之前进行低温超导测试(2K、4K)。为满足25MeV超导直线加速器调试运行,需要建造一套超导低温测试系统与实验平台,用来对超导腔的性能进行垂直测试,检验腔体是否达到设计目标,使其满足工程使用需求。     

BEPCⅡ低温控制系统研制

北京正负电子对撞机重大改造工程(BEPCⅡ)首次应用低温超导技术建造低温系统. 低温控制系统通过控制前端低温系统的压力、液位、流量和功率等过程变量, 分别产生饱和液氦、两相氦和过冷的单相液氦, 使用这三种不同形式的氦流来冷却超导设备. 低温控制系统采用EPICS+PLC双层架构体系, 实现对前端低温超导设备的全自动控制. EPICS主要完成低温系统的过程控制、逻辑控制和PID闭环控制; PLC负责前端关键设备的联锁控制, 用于保护低温超导设备的安全.     

BEPCⅡ低温控制系统研制

北京正负电子对撞机重大改造工程(BEPCⅡ)首次应用低温超导技术建造低温系统.低温控制系统通过控制前端低温系统的压力、液位、流量和功率等过程变量,分别产生饱和液氦、两相氦和过冷的单相液氦,使用这三种不同形式的氦流来冷却超导设备.低温控制系统采用EPICS+PLC双层架构体系,实现对前端低温超导设备的全自动控制.EPICS主要完成低温系统的过程控制、逻辑控制和PID闭环控制;PLC负责前端关键设备的联锁控制,用于保护低温超导设备的安全.     

ADS注入器Ⅱ10MeV加速器液氦分配系统设计

ADS注入器Ⅱ超导加速段的运行需要在4.2K(液氦)超低温环境下进行,针对注入器Ⅱ10MeV加速器低温恒温器的运行要求设计了一套液氦分配系统,该系统在满足加速器的低温恒温器工作的同时还具备给超导腔水平测试、垂直测试、磁铁测试等试验终端供液以及调节流量的功能。系统已应用于5 MeV加速器液氦的分配与调节以及超导腔垂直测试系统中,运行良好。重点介绍了液氦分配系统的工艺流程、阀箱的结构设计及调试运行情况。     

35kV/90MVA高温超导限流器低温系统

35kV/90MVA高温超导限流器的低温系统是一个开放式的液氮制冷系统,包括一个环形不锈钢杜瓦、真空绝热管、压力及温度传感器、低温阀门以及监控系统.高温超导磁体放置在杜瓦中;监控系统检测杜瓦内液氮的液面,并控制往杜瓦内进行补液.杜瓦内蒸发的氮气通过真空绝热管道直接排放到大气中.分别对不同工况下的液氮蒸发量进行了测量.进...     

ADS注入器Ⅱ低温恒温器控制系统

设计了用于ADS注入器Ⅱ超导腔的低温恒温器控制系统。采用了基于EPICS 的分布式控制系统架构,以PLC 和串口服务器等为核心控制硬件,用PID 算法实现了恒温器内氦压和液氦量的自动控制,压力控制精度约为100 Pa,液氦高度误差约10 mm。利用EPICS 和LabVIEW 在局域网发布过程数据,实现了操作员界面对低温恒温器分布式系统的统一管理,控制系统设计性能满足使用需求,已经在ADS注入器Ⅱ超导高频腔水平测试中发挥了重要作用。Cryogenic module provides important low temperature environment for half wave resonance superconducting cavity in C-ADS injector Ⅱ, to ensure the effective operation of cryogenic module, a remote control system which is based on the physical and experimental industrial control systems (EPICS) is introduced in this paper. PLC and serial port server are used as field controllers. Host computer runs EPICS and LabVIEW which are capable of getting and releasing data in local area net. Operators manage all the equipments through a CSS interface which is linked to local area net. The control system which is simple structure and reliable work, has played an important role in the level test of HWR superconducting cavity.     

基于模型预测控制的低温控温策略设计及实验验证

低温温度计的标定中，控温策略是低温温度计标定效率和精度的重要影响因素。本研究搭建了以液氦为冷源的低温温度计全自动标定系统，通过温控仪和Python/QT编写了上位机控制程序，对标定过程中所遇到的控温性能问题进行研究。提出一种基于模型预测控制和PID结合的控温策略，通过计算机仿真进行参数优化与实验测试的方法，对PID控温和模型预测控制控温进行实验验证。结果表明，采用模型预测控制后，温度超调量仅为PID模式下的45.42%,稳态调节时间缩短为PID下的23.61%。该控制方法能够显著提高低温系统的控温性能。     

Field measurement for superconducting magnets of ADS injector Ⅰ

A superconducting magnet prototype for Accelerator Driven Sub-critical System Injection-Ⅰ had been designed and fabricated, and tested in a new made vertical Dewar in November 2012. Batch magnet production was processed after some major revision from the magnet prototype, they include: removing off the perm-alloy shield, extending the iron yoke, using thin superconducting wire, etc. The first one of the batch magnets was tested in the vertical Dewar at the Harbin Institute of Technologyin in September 2013. A field measurement was carried out at the same time by the measurement platform that was seated on the top of the vertical Dewar,the measurement results met the design requirements. This paper will present the field measurement system design, measurement results and discussion on the residual field from the persistent current effect.     

Physical design of superconducting magnet for ADS injection Ⅰ

A superconducting solenoid prototype magnet for Accelerator Driven Subcritical System (ADS) Injection Ⅰ has been designed and fabricated, which has also been tested in a liquid Helium state inside a vertical Dewar in the Haerbin institute of Technology in November 2012. The design current was 210 A, when the test current reached 400 A no quench occurred so the solenoid magnet was forced to quench by the embedded heaters. The integral field strength, leakage field at the nearby upstream and downstream superconducting spoke cavities all meet the design requirements. At the same time, it also checked the reliability of the vertical test Dewar and the quenched detection system. The superconducting prototype magnet has accumulated valuable experiences for the coming batch magnets production and cryogenic test.     

G-M制冷机辐射屏温度随动控制

该文提出低温与超导系统温度控制新方法 -基于泛逻辑代数的温度随动控制。这是一种以低温实验为基础 ,依据概念和专家知识的泛逻辑控制 ,控制特性用一组泛逻辑代数方程描述 ,从而可以有效解决 G- M制冷机辐射屏温度的随动控制问题。该系统可应用于低温界面热阻实验和超导材料热物性测试等。温度随动控温范围为 4 0 K- 15 0 K,精度优于3K。这对低温与超导技术等有重要意义     

An externally cooled beetle type scanning tunneling microscope for imaging in cryogenic liquids

We describe a variable temperature cryogenic scanning tunneling microscope designed for imaging and research in cryogenic liquids. It has an external Dewar type large scale cooling system with a temperature control range of roughly 85-110 K using pressure controlled liquid nitrogen cooling. The liquid nitrogen is kept in a closed chamber surrounding the STM and maintained at a pressure to suit the chosen temperature. Several gases have triple points in this temperature range and can therefore be liquified, such as argon, methane, silane and germane. The STM is based on a beetle type design built into a small cube vacuum chamber to fit into the cooling dewar. The system has been used for atomic resolution of highly oriented graphite submerged in a methane liquid at a temperature of 100 K.     

Study on cooling process of cryogenic system for superconducting magnets of BEPCⅡ

In the upgrade project of the Beijing Electron Positron Collider(BEPCⅡ),three superconducting magnets are employed to realize the goal of two orders of magnitude higher luminosity.A cryogenic system with a total capacity of 0.5 kW at 4.5 K was built at the Institute of High Energy Physics(IHEP)to support the operations of these superconducting devices.For preparing the commissioning of the system,the refrigeration process Was simulated and analyrzed numerically.The numerical model Was based on the latest engineering progress and focused on the normal operation mode.The pressure and temperature profiles of the cryogenic system are achieved with the simulation.The influence of the helium mass flow rates to cool superconducting magnets on the thermodynamic parameters of their normal operation is also studied and discussed in this paper.     

高温超导直接冷却的氮化铝与无氧铜接触界面热阻的实验研究

氮化铝(AlN)具有高热导性、高电绝缘性,是超导二元电流引线热截流结构中常用的材料之一。根据稳态导热法建立低温真空实验装置,实验研究了超导冷却系统热截流结构中,界面温度和接触压力对AlN块材与无氧铜(OFHC-Cu)块材间接触界面热阻的影响。在实验温度(90K-210K)和压力(0.273MPa-0.985MPa)条件下,AlN/OFHC-Cu接触界面热阻随接触压力的提高而降低,而当界面温度上升时界面热阻由于热载子热运动的强化而降低,温度较高时,接触界面热阻随压力变化的速率趋缓。低温下AlN/OFHC-Cu间的接触界面热阻是直接冷却超导系统的设计和超导系统的热稳定性方面必需解决的问题。     

The cryogenic control system of BEPCⅡ

A superconducting cryogenic system has been designed and deployed in the Beijing Electron-Positron Collider Upgrade Project(BEPCⅡ).The system consists of a Siemens PLC(ST-PLC,Programmable Logic Controller)for the compressor control,an Allen Bradley(AB)PLC for the cryogenic equipments,and the Experimental Physics and Industrial Control System(EPICS)that integrates the PLCs.The system fully automates the superconducting cryogenic control with process control,PID(Proportional-Integral-Differential)control loops,real-time data access and data storage,alarm handler and human machine interface.It is capable of automatic recovery as well.This paper describes the BEPCⅡ cryogenic control system,data communication between ST-PLC and EPICS Input/Output Controllers(IOCs),and the integration of the flow control,the low level interlock,the AB-PLC,and EPICS.     

低温二次电子产额测试系统设计与研究

在合肥先进光源（HALF）建设中,由低温超导材料组成的真空部件被大量使用,尤其是超导高频腔。超导腔以高加速梯度、低束流阻抗、高无载品质因数和低运行成本等特点,成为21世纪国际上拟建的大型加速器的首选。而超导腔和低温真空室内表面的二次电子发射可能会引发电子云（EC）现象。超剂量的二次电子倍增功率沉积会引起低温区域热负载增加、超导腔失超等现象,因此降低超导高频腔内二次电子发射成为合肥先进光源设计过程中的巨大挑战。在常温材料二次电子产额（SEY）测试系统的基础上,作者自主研发设计低温样品架结构,使液氦流经样品台并通过热传导冷却样品,计算漏热来反推所需要的制冷量和液氦的消耗速率。在系统集成调试后进行降温性能测试,搭建了低温材料二次电子测试系统。     

BEPCⅡ超导腔垂直测试杜瓦的漏热分析与实验研究

北京正负电子对撞机重大改造工程(简称BEPCⅡ)采用了超导射频技术,超导腔设备在与低温恒温器总装之前,必须进行液氦温度下垂直位置的性能测试.测试杜瓦的绝热性能对超导腔的垂直测试性能产生直接影响,准确测算测试杜瓦的漏热量对垂直测试方案的制定、减少液氦消耗量具有重要的指导意义.对测试杜瓦的主要漏热部分进行了计算,同时以液氮...     

上海光源500MHz超导腔水平测试

上海光源是能量为3.5 GeV的第三代先进中能同步辐射光源,其储存环上安装了三台超导高频腔补偿电子因同步辐射等原因丢失的能量。为保障上海光源的长期稳定高效运行,中国科学院上海应用物理研究所和上海市低温超导高频腔技术重点实验室共同研制了具备低高次模损失参数和可承受更高入射功率的新型500 MHz超导腔,作为上海光源在线运行超导高频腔的备用腔。超导铌腔经低温垂直测试达到所需加速性能后,需要与高功率输入耦合器、高次模吸收器、低温恒温器等集成并完成水平测试,获得超导腔模组的加速性能、低温性能和真空性能。介绍了超导腔备用腔的研制、集成和测试过程,采用文丘里(Venturi)校准法获得模组的静态功耗反应模组的低温性能,并通过高功率测试获得了超导腔备用腔模组的加速性能。测试结果表明:自主研制的500 MHz超导腔备用腔满足上海光源的工作需求,在超导腔的加速腔压为2.0 MV时,无载品质因数为1.2×109 @4.2 K,且低温模组的静态热损耗为36.1 W。