BEPCⅡ SSM磁体控制阀箱内氦冷却管线热应力分析

北京正负电子对撞机重大改造工程(BEPCⅡ)超导螺线管磁体(SSM)的控制阀箱是该磁体低温冷却系统的主要设备之一,用来分配、调节和控制超导磁体及其电流引线的冷却介质流量.低温下磁体超导导线及其冷却管会产生冷缩变形,变形量要在控制阀箱内给与补偿.同时阀箱内来流和回流氦冷却管线布置紧凑,需要判断是否要采取措施来补偿冷缩变形.本文运用有限元分析软件ANSYS对BEPCⅡ SSM控制阀箱内冷却管线的热应力进行模拟及分析,从而为该阀箱内冷却管线的设计及布局提供理论依据.     

EAST超导托卡马克热负荷波动对低温系统液氦槽的影响

EAST超导托卡马克的纵场和极向场磁体均采用NbTi超导材料,由3.8 K超临界氦冷却.在托卡马克实验运行时,极向场的放电脉冲和等离子体破裂产生的交流损耗带来的热负荷增加,经过超临界氦流带到低温系统控制阀箱内的液氦槽和过冷槽,造成槽内的液氦蒸发量增加.蒸发的氦回到制冷机中,从而影响制冷机的稳定运行.通过对实际超临界管道和液氦槽、过冷槽中换热过程建立换热模型,进行热工分析,分析液氦槽和过冷槽中的压力等参数的变化,指导低温系统的设计.     

ITER CC导体接头测试装置设计与研制

根据国际热核实验反应堆(ITER)校正场线圈(CC)导体接头低温电阻的测试要求,设计并研制了一套用于超导导体接头的低温测试装置。该装置主要包括10 kA超导变压器、低温测试杜瓦、磁体失超保护系统和数据采集系统等。超导变压器的初级线圈及次级线圈采用LHe浸泡的方式进行冷却。超导变压器初级线圈电流引线采用常规铜电流引线,为增加铜的传热面积,采用编织铜引线代替铜棒引线。初级线圈外接磁体电源,利用电磁感应原理,在次级回路感应出超导导体接头测试所需的电流。已经成功进行了一次CC导体接头的低温实验,接头电阻的测试结果分别为8.4纳欧姆和9.3纳欧姆。     

300kW超导单极电机低温技术及试验研究

简述了３００ｋＷ超导单极电机试验的低温系统，介绍了超导单极电机的磁体低温系统及液氦、液氮冷却，输液及运行情况，分析比较了多次试验研究的结果。     

浙江蒙德克流体控制有限公司

<正>浙江蒙德克流体控制有限公司是专业生产各种流体控制阀的实体,拥有一支从事了几十年控制阀研究开发、制造及工程设计应用的专业队伍,公司现已成功取得了国家六项产品专利。企业主要生产:MDK系列自力式调节阀、气(电)动直行程调节(切断)阀、气(电)动角行程调节(切断)阀及特种阀门(含双向严密封紧急切断程控阀、深冷场合使用的低温和超低温真空绝热调节阀、膨胀机配套用精密减压阀、薄膜(活塞)执行机构和紧急低温切断阀。     

管内电缆导体稳定性研究方法新探

管内电缆导体（ＣＩＣＣ）,是目前大型低温超导磁体的首选导体。随着超导技术的发展,ＣＩＣＣ在大型超导核聚变实验装置及超导储能磁体中的应用具有不可比拟的优越性。为降低导体成本而提出了在ＣＩＣＣ中采用的超导股线配以纯铜股线的设计方案,开展含纯铜股线ＣＩＣＣ稳定性机理及实验的研究,并开发ＣＩＣＣ优化设计软件,对ＣＩＣＣ在高科技术中的应用意义重大。     

高温超导磁储能(SMES)磁体直接冷却热输运过程研究

随着高温超导材料与低温技术的发展，采用制冷机直接冷却已经成为高温超导应用的发展方向，而界面热阻则直接影响着超导器件的冷却效率和运行可靠性，因此减小和控制低温界面热阻是实现超导系统直接冷却的技术关键。对直接冷却高温超导磁体从室温冷却到49K低温的热输运过程进行了理论分析和实验研究，磁体冷却实验结果和理论分析符合较好，通过直接冷却实验所达到的最低温度特性和过程分析，证实从微结构低温工程学的角度研究界面热阻、探索超导直接冷却最佳热耦合机制是高温超导应用基本而重要的科学问题之一。     

螺杆式压缩机内置活塞式进气控制阀分析

对内置活塞式进气控制阀在螺杆式压缩机上的应用原理及其作用进行阐述,进气控制阀的压损、吸气侧的筒直径及其弹簧力大小是影响阀打开力大小的3个主要因素。阀打开力与阀的压损、阀体吸气侧筒的直径平方几乎呈正比关系,弹簧力是阻碍阀打开的因素,弹簧力减小的数值就是阀打开力增大的数值。在进气控制阀的设计上,对螺杆式压缩机的性能和进气控制阀可靠性必须综合考虑,进气控制阀设计参数选择要合适,在确保阀打开可靠的前提下,阀的压损一般控制在25-30 kPa范围内。     

EAST超导托卡马克冷屏的结构设计及受热分析

EAST是一个拥有全超导磁体系统的托卡马克实验装置.为有效减少来自真空室和外真空杜瓦的辐射热以及支撑的传导热等各项热负荷,超导纵场磁体和极向场磁体被约80 K的真空室冷屏(内冷屏)和外真空杜瓦冷屏(外冷屏)所包容,从而保证磁体运行的稳定可靠.运用大型有限元分析程序ANSYS和FLUENT,对冷屏的受热状况进行了数值分析,为其结构设计和低温制冷方案的制定提供可靠的理论依据.     

北京正负电子对撞机重大改造工程超导腔恒温器静态热负荷分析

北京正负电子对撞机重大改造工程(BEPCII)采用了频率为500 MHz的单cell超导纯铌腔作为加速腔.通过有限元分析的方法对超导腔恒温器各部件进行热模拟和分析,并将模拟分析结果与超导腔的水平测试结果进行比较验证,确认数值分析结果为可信的,且得出对备用超导腔恒温器设计、加工和运行具有指导意义的结果.     

基于液氮冷源超导磁体氦气循环预冷系统设计

为了提高超导磁体300-80 K预冷过程中的降温效率和安全性,开发了一种新的预冷方法.设计了一台以液氮为冷源、氦气为循环介质的可控温预冷装置,对其内部结构进行了优化设计,包括低温风机、板式换热器、气动调节阀、翅片换热器等主要组成部分,整个装置与磁体构成一个闭合循环系统.在预冷装置的作用下,该超导磁体从300 K到80 ...     

Refrigerator-recirculator systems for large forced-cooled superconducting magnets

Forced-cooled superconductors are viewed as a promising alternative in the development of high field superconducting magnets for future fusion devices. The high current density cable superconductor is protected against thermal instabilities by forcing (single phase) supercritical helium through the cable.The cryogenic cooling system for a forced-cooled superconducting magnet works as a refrigerator and a reciculator at the same time. The paper discusses the conceptual design of the cooling systems for forced-cooled superconducting magnets with the overall objective of reducing the refrigeration costs. The general conclusion of this article is that economic cooling systems must employ efficient cold pump recirculators in which the large flow demanded by the forced-cooled superconducting magnet is confined to the cold end of the refrigerating column. If the liquid helium pump efficiency is less than 40%, systems employing elevated temperature compressors are more economic.     

部分流超临界氦循环泵特性分析

通过将大型超导托卡马克装置中用于超导磁体冷却的超临界氦循环泵与传统离心泵进行比较,对BNI(Barber-Nichols Inc.)部分流超临界氦循环泵进行了结构特点和性能特点分析,重点讨论了叶轮、叶片和蜗壳的结构差异,以及由于这些结构的不同决定的流量、扬程和效率差异,为部分流超临界氦循环泵的设计及试验研究提供了理论依据.     

Development of a Superconducting Magnet System with Zero Liquid Helium Boil-off

A homogeneous magnetic field superconducting magnet with a cold bore of 250 mm and a central field of 4.3 T has been designed, manufactured, and tested with zero liquid helium boil-off. As a result of magnetic field homogeneity considerations, the magnet is composed of three coaxial coils: one main coil and two compensation coils. All coils are connected in series and can be charged with a single power supply. The magnetic field homogeneity is about ±3.0 % from ?200 mm to 200 mm in axial direction with 86 mm in diameter. The magnet can be operated in persistent mode with a superconducting switch. A two-stage GM cryocooler with a capacity of 1.5 W at 4.2 K was used to cool the superconducting magnet. The cryocooler prevents the liquid helium from boiling off and leads to zero helium loss during static operation. The magnet can be operated in liquid helium circumstance by cooling the gas helium with the cryocooler without additional supply of liquid helium. Under this condition, the magnet is successfully operated up to 4 T without quench. The magnet system can be generating 0.25 L/h liquid helium with the cryocooler by supplying the gas helium without loading the magnet. In this paper, the magnet design, manufacture, mechanical behavior analysis, and the performance test results of the magnet are presented.     

Superconductivity and cryogenics for linear accelerator programme at IUAC, New Delhi

The Inter-University Accelerator Center, New Delhi is involved in commissioning a superconducting linear accelerator (LINAC) as a booster to its existing 15 UD Pelletron accelerator. The booster consists of three LINAC modules, each containing eight superconducting Nb quarter wave resonators and a superconducting solenoid magnet. The first LINAC module preceded by a superbuncher with one cavity and followed by a rebuncher cryostat with two cavities was installed in 0° beam line of Pelletron and has been under operation for some time at the Center. The module is integrated with a liquid helium (LHe) refrigerator through a cryogen valve box and the distribution line. The performance tests of each component like the RF cavity, the cryomodule and the liquid helium distribution line were carried out independently prior to the beam acceleration test. After having many trial runs on this integrated cryonetwork system, beam acceleration tests were performed during 2007. The energy of silicon beam with charge state of +10 has been enhanced approximately from 130 MeV to 158 MeV using the first module with seven effective cavities and the accelerated beam was delivered at user’s scattering chamber. The present paper highlights the performance of the first module producing an accelerating beam duly bunched in the rebuncher. The performance of first LINAC cryomodule along with problems and the solution associated with the cryogenic system and the cavities encountered during the beam runs are presented in this paper.     

Operational Characteristics of the 200-m Flexible Cryogenic Transfer System

A proper cryogenic environment is essential for the operation of superconducting devices. A test area for the superconducting radio-frequency modules (SRF) has been established in the RF laboratory at National Synchrotron Radiation Research Center in Taiwan; these modules require much liquid helium during conditioning and performance tests; a cooling capacity of 120 W is expected for the acceptance test of the SRF module. The cryogenic environment of the test area is completed on transferring the liquid helium over a remarkable length of 205 m from the two cryogenic plants at Taiwan Light Source, with a valve box located at each end to control and to measure the cryogenic flow. Flexible cryogenic transfer lines of concentric four-tube type are chosen for both the supply of liquid helium and the return of cold helium gas. Functional examination of this long transfer system was first achieved with a 500-L Dewar in the radio-frequency laboratory; an SRF module was then installed in the test area for practical operation. The primary concern about the cryogenic transfer system is the heat loss; a measurement technique based on the principle of thermodynamics is developed and proposed herein. With the available sensors inside the valve boxes and the heaters inside the 500-L Dewar and the test SRF module, this technique has proved promissing from the measured results.     

The cryogenic system for ITER CC superconducting conductor test facility

This paper describes the cryogenic system of the International Thermonuclear Experimental Reactor (ITER) Correction Coils (CC) test facility, which consists of a 500 W/4.5 K helium refrigerator, a 50 kA superconducting transformer cryostat (STC) and a background field magnet cryostat (BFMC). The 500 W/4.5 K helium refrigerator synchronously produces both the liquid helium (LHe) and supercritical helium (SHe). The background field magnet and the primary coil of the superconducting transformer (PCST) are cooled down by immersing into 4.2 K LHe. The secondary Cable-In-Conduit Conductor (CICC) coil of the superconducting transformer (SCST), superconducting joints and the testing sample of ITER CC are cooled down by forced-flow supercritical helium. During the commissioning experiment, all the superconducting coils were successfully translated into superconducting state. The background field magnet was fully cooled by immersing it into 4.2 K LHe and generated a maximal background magnetic field of 6.96 T; the temperature of transformer coils and current leads was reduced to 4.3 K; the inlet temperature of SHe loop was 5.6 K, which can meet the cooling requirements of CIC-Conductor and joint boxes. It is noted that a novel heat cut-off device for High Temperature Superconducting (HTS) binary current leads was introduced to reduce the heat losses of transformer cryostat.     

Economical Running of BEPCII Cryogenic System

BEPCII cryogenic system consists of a cavity cooling loop and a magnet cooling loop. Although the magnet cooling loop has lower heat load than the cavity cooling loop, it needs much more helium mass flow since only sensible heat of the supercritical helium is used to cool the SCQ magnets. As a result, excess liquid helium exists in the return line of the magnet cooling loop and should be evaporated by electrical heater, leading to a waste of cooling power. This paper discusses several solutions for operating the system economically.     

Incorporating Artificial Neural Networks in the dynamic thermal–hydraulic model of a controlled cryogenic circuit

A model based on Artificial Neural Networks (ANNs) is developed for the heated line portion of a cryogenic circuit, where supercritical helium (SHe) flows and that also includes a cold circulator, valves, pipes/cryolines and heat exchangers between the main loop and a saturated liquid helium (LHe) bath. The heated line mimics the heat load coming from the superconducting magnets to their cryogenic cooling circuits during the operation of a tokamak fusion reactor. An ANN is trained, using the output from simulations of the circuit performed with the 4C thermal–hydraulic (TH) code, to reproduce the dynamic behavior of the heated line, including for the first time also scenarios where different types of controls act on the circuit. The ANN is then implemented in the 4C circuit model as a new component, which substitutes the original 4C heated line model. For different operational scenarios and control strategies, a good agreement is shown between the simplified ANN model results and the original 4C results, as well as with experimental data from the HELIOS facility confirming the suitability of this new approach which, extended to an entire magnet systems, can lead to real-time control of the cooling loops and fast assessment of control strategies for heat load smoothing to the cryoplant.