Preliminary Calculation of Electromagnetic Loads on Vacuum Vessel of HL-2M

For a robust design of vacuum vessel of HL-2M, the electromagnetic （EM） loads have to be understood clearly. In this paper, some crucial transient events, such as plasma major disruptions （MDs）, vertical displacement events （VDEs）, fast discharge of toroidal field （TF） coils, have been investigated to evaluate the eddy currents and EM forces on vacuum vessel and in-vessel components. The results show that the eddy currents depend strongly on the current decay time, and the maximum toroidal eddy current flowing in the whole vessel can reach up to 2.4 MA during MDs that is close to the plasma current. Large symmetric radial forces and a net vertical force on vessel shells could be caused by these transient events. Combination of eddy currents in in-vessel components and toroidal field could twist the copper plates and other internal parts, however, if these plates are supported and connected carefully, the twist moments will not have a big effect on the vessel shells and vessel support.

Numerical Simulation Approaches to Evaluating the Electromagnetic Loads on the EAST Vacuum Vessel

Numerical simulation approaches are developed to compute the electromagnetic forces on the EAST vacuum vessel during major disruptions and vertical displacement events, with the halo current also considered. The finite element model built with ANSYS includes the vacuum vessel, the plasma facing components and their support structure, and the toroidal and poloidal field coils. The numerical methods are explained to convince of its validity. The eddy current induced by the magnetic flux variation and the conducting current caused by the halo current are also presented for discussion. The electromagnetic forces resulting from the numerical simulation are proven to be useful for structure design optimization. Similar methods can be applied in the upgrades of the EAST device.

A Lower Rigid Support Structure for the HT-7U Vacuum Vessel

Vacuum vessel of the HT-7U is a fully welded toroidal structure with a noncircular cross-section nested in the bore of the TF coils. According to the requirement of the physics design, sixteen horizontal ports on outboard mid-plane and thirty-two vertical ports on the top and bottom are designed for diagnostics, plasma heating, current driving, vacuum pumping and gas puffing. Bellows on these port necks are used for flexible components to absorb the relative displacement in radial and vertical directions due to external load, thermal expansion or contrac-tion and assembly tolerance, and also used for isolation of mechanical vibration. For the support system of vacuum vessel it should be not only strong enough to withstand forces acting on the vessel interior components and the vessel itself due to the dead weight and electromagnetic inter-actions during plasma disruption, but also sufficiently flexible to be suited to thermal expansion during baking. In order to solve this contradiction a new kind of low rigid support has been designed, which has a perfectly rigid in vertical direction and perfectly soft in radial direction. Some three-dimension finite element COSMOS models were performed to analyze their structural strength, stiffness and fatigue life, with an emphasis on the static stress analysis. The load spectra during vacuum vessel operation were also simulated on these models in the view of fatigue design. It was confirmed that the bellows and support had sufficient strength in the designed range of the load conditions. The results showed that the peak stress on bellows was 87 MPa and on the support system was 97 MPa. Now all kinds of bellows and support system have been designed. In order to accumulate some engineering experiences and probe into some molding die and welding technologies, prototypical bellows and support system have been fabricated. At the same time a mechanical testing apparatus was designed for proof tests on the prototypical bellows and support to verify their functional and structure capability. The experimental data indicated that the re-sults of finite element analysis were coincident with experimental test results. It has been proved that the present vacuum vessel's bellows and support system are reasonable and feasible.

Static and Dynamic Mechanical Analyses for the Vacuum Vessel of EAST Superconducting Tokamak Device

EAST （experimental advanced superconducting tokamak） is an advanced steadystate plasma physics experimental device, which is being constructed as the Chinese National Nuclear Fusion Research Project. During the plasma operation the vacuum vessel as one of the key component will withstand the electromagnetic force due to the plasma disruption, the Halo current and the toroidal field coil quench, the pressure of boride water and the thermal load due to 250℃ baking by pressurized nitrogen gas. In this paper a report of the static and dynamic mechanical analyses of the vacuum vessel is made. Firstly the applied loads on the vacuum vessel were given and the static stress distribution under the gravitational loads, the pressure loads, the electromagnetic loads and thermal loads were investigated. Then a series of primary dynamic, buckling and fatigue life analyses were performed to predict the structure＇s dynamic behavior. A seismic analysis was also conducted.

An Optimized Structure Design of the HT-7U Vacuum Vessel

The vacuum vessel of the HT-7U superconducting tokamak will be a fully-welded structure with a double-wall. The space between the double-wall will be filled with borated water for neutron shielding. Non-circular cross-section is designed for plasma elongating. Horizontal and vertical ports are designed for diagnosing, vacuum pumping, plasma heating and plasma current driving, etc. The vacuum vessel consists of 16 segments. It will be baked out at 250℃ to obtain a clean wall. When the machine is in operation, both the hot wall (the wall temperature is around 100℃) and the cold wall (wall temperature is in normal equilibrium) are considered. The stress caused by thermal deformation and the electromagnetic (EM) loads caused by 1.5 MA plasma disruption in 3.5 T magnetic field have to be taken into account in the design of the HT-7U vacuum vessel Finite element method was employed for structure analysis of the vacuum vessel.

Linear Buckling Analysis of the HT-7U Vacuum Vessel

The vacuum vessel of the HT-7U superconducting Tokamak is designed as an allmetal welded double-wall structure with a number of radial and vertical ports. With characteristicsof ultrahigh vacuum and thin shell, the analysis on stability is very important to the design. Toachieve a successful final design, a threedimension buckling model has been performed using thefinite element program CoSMOS/M2.0. For all the cases having been considered, a 1/16 segmentof the whole toric shell are used to calculate the linear critical buckling load (Pc.,,) under auniform and nonwhform external pressure. As expected, the structure has a good capability ofwithstanding the applied loads.

Electrical Parameters of the Vacuum Vessel in HT-7U Tokamak

A method is presented to express the electrical parameters of the vacuum vessel in this paper. According to the results of numerical computation and the distribution of the eddy currents, the mutual inductance can be given by calculating the flux produced by the toroidal eddy currents. The time constants of the vacuum vessel of HT-7U tokamak are derived from the decay characteristics of the eddy currents.

Numerical Analysis on Neutron Shielding Structure of ITER Vacuum Vessel

The neutron shielding component of ITER （International Thermonuclear Experimental Reactor） vacuum vessel is a kind of structure resembling a wall in appearance. A FE （finite element） model is set up by using ANSYS code in terms of its structural features. Static analysis, thermal expansion analysis and dynamic analysis are performed. The static results show that the stress and displacement distribution are allowable, but the high stress appears in the junction between the upper and lower parts. The modal analysis indicates that the biggest deformation exists in the port area. Through modal superposition, the single-point response has been found with the lower rank frequency of the acceleration seismic response spectrum. But the deformation and the stress values are within the permissible limit. The analysis results would benefit the work in the next step and provide some reference for the implementation of the engineering plan in the future.

低温容器用多层绝热材料的绝热性能研究进展

多层绝热材料被广泛应用于低温容器,其绝热性能是人们重点关注的性能指标。真空良好下,影响其绝热性能的因素包括夹层真空度、材料型号和种类、层数、层密度、等密度或变密度布置以及材料包覆工艺等;真空失效下,夹层气体压力、破空气体种类以及绝热结构参数等会对多层绝热材料的绝热性能产生影响。本文综述了多层绝热材料绝热性能的预测公式。应用Lockheed分析模型对不同边界温度、不同层数下的多层绝热材料的绝热性能进行预测,得到最佳层密度和最小热流密度;在层数一定的条件下,应用Layer-by-layer传热模型对等密度和变密度多层绝热方案的绝热性能进行预测,分析获得了两种实用性较高的多层绝热方案。

未来聚变堆真空室扇区现场高精度装配技术研究

在CRAFT真空室1/8段的装配研究中,设计了用于补偿扇区间装配误差的过渡段,介绍了其制造方案,研制了在线铣削系统以保证项目现场的高精度装配。

CFETR真空室结构稳定性的有限元分析

真空室是中国聚变工程实验堆(CFETR)重要的屏蔽组件和包容屏障,为提高其结构稳定性,用有限元方法对真空室核心部件进行了线性屈曲分析与几何初始缺陷非线性屈曲分析,评估了真空室结构的各项稳定性指标。结果表明,现有的真空室的设计满足屈服强度的设计要求,为后续的设计优化工作提供了重要的理论依据和参考。

某大型真空容器结构稳定性分析与试验评价

真空容器广泛应用于航空航天领域,其结构稳定性是考核设计的重要指标。针对复杂异形真空容器规则设计的不确定性及仿真评估的准确性缺陷,本文构建了某大型真空容器模型,在工艺设备质量、0.1 MPa外压力和重力条件下分析了容器应力、位移和屈曲指标。组建了一套由应变、位移、压力测试组成的真空容器结构稳定性测试系统,采用分段、连续两种抽真空模式,获取了经典测点的应力、位移试验数据,提出了针对大型真空容器结构稳定性试验评价方法。结果发现:能够有效的验证真空容器前期的设计计算和有限元仿真的准确性。该方法为提高仿真准确性提供了优化方向,有助于真空容器研制及验收工作。

负离子源测试平台真空室结构设计及优化

负离子源测试平台是用于开展未来磁约束聚变装置中性束注入系统负离子束源性能研究的测试装置。研究分析了负离子束源性能特征及测试方法,基于测试平台工程及物理设计需求,完成了国内首台以盒形壳体作为结构模式的大功率负离子源中性束注入系统(Negative ion based Neutral Beam Injection system,NNBI)束源测试平台真空室的结构设计及重要部件的集成。运用ANSYS Workbench软件建立有限元模型,数值分析了真空室结构静态力学特性,得到了应力与变形分布规律,并通过应力线性化分类处理与响应面的方法分别进行了各类应力评估和束线真空室变形最大的后端封头的结构优化。结果表明:真空室的结构强度与变形量均满足工程设计需求,优化后的封头变形幅值显著降低,为负离子源测试平台的集成设计优化与研制奠定了基础,具有工程应用价值。

空间站高温材料科学实验系统真空室设计与分析

中国空间站高温材料科学实验系统能够在轨进行多种材料的微重力高温加热实验,其关键组件真空室是可实现密封的压力容器,为实验插件提供机械、真空、氮气、废气排放、供电、控制、冷却等接口,支持实验插件完成相关功能。本文依据承压范围、漏率等设计技术指标进行真空室的结构设计和力学分析。真空室采用分段式结构,由方形真空室、密封门、圆形真空室、安装支架等组件依次连接组成,连接结构处使用密封圈。通过真空室的承压分析、模态分析、随机响应分析和力学试验,校核了真空室的强度、刚度及随机振动响应特性,验证了真空室设计的安全性和可靠性,其能够满足发射及在轨工作要求。

基于PSO-LSTM的低温压力容器真空失效程度时序预测

针对低温压力容器在运行过程中可能受到震动等影响导致的真空夹层泄漏、真空夹层压力上升以及内胆压力快速升高等问题,设计了一种结合群智能算法与神经网络的低温压力容器真空失效程度时序预测算法。通过对低温压力容器真空失效的过程进行简化仿真模拟,获取低温压力容器真空失效过程中的各参数变化情况,形成失效数据集。使用该数据集进行长短期记忆网络(LSTM)模型训练以预测低温压力容器真空失效程度,结合粒子群算法(PSO)对LSTM模型的超参数进行寻优。最后使用训练完成的PSO-LSTM模型对低温压力容器真空失效程度进行时序预测,并对该时序预测模型的预测效果进行了分析。

MPC在EAST真空室烘烤中应用研究

烘烤系统作为EAST(Experimental Advanced Superconducting Tokamak)重要的支撑系统之一,存在大时滞和模型不精确等问题,难以实现稳定控制烘烤温度。因此本文提出将MPC(Model Predictive Control)方法应用于烘烤系统,首先通过理论推导和曲线拟合方法构建了烘烤设备和烘烤环节模型。其次基于烘烤系统模型设计预测控制器和控制方案流程,最后在烘烤平台上验证控制方法的有效性。在稳定烘烤期间,真空室烘烤温度波动小于6℃,并且加热器输出功率平稳,功率波动小于1 kW。实验结果表明MPC方法能够稳定控制真空室烘烤温度,并满足真空室烘烤要求。

超大型真空容器大门设计及优化研究

本文以直径10m的超大型真空容器大门为研究对象,介绍了超大型立式容器大门的设计分析情况,采用可靠性设计与仿真优化相结合的方法,对大门在外压和起吊时的强度和变形分布进行了模拟分析,并根据分析结果对大门加强筋布置进行了优化设计。研究表明:在封头曲率变化较大处与加强筋之间设置补强板,可以有效减少大门局部应力超限的问题;封头加强筋减少至6根可以降低材料用量,此时最大应力为97.37MPa,最大变形为4.1mm,仍然可以满足材料使用要求;大门起吊时整体承受重力载荷,最大变形量为0.13mm,最大应力为18.6MPa,满足材料使用要求。

凝汽式汽轮机机组启动前抽真空时间的计算方法及应用

凝汽式汽轮机机组启动前需要将凝汽系统通过抽气设备形成一定的真空度,而众多有关凝汽系统的资料中都没有给出通过抽气设备将凝汽系统从大气压抽取至某一真空压力时所需时间的计算方法。探究射汽抽气器或水环式真空泵这两种抽气设备将凝汽系统抽取至一定真空时的时间计算方法,同时引申至密闭容器通过恒定体积流量的抽气设备抽吸真空所需的时间计算或容量选取。

应变强化技术在深冷压力容器中的应用

与采用常规技术设计和制造深冷压力容器相比,采用应变强化技术设计和制造深冷压力容器能节省30%~45%的材料。深冷压力容器轻量化是提高企业市场竞争力的核心技术。通过统计和分析珠海森铂低温能源装备有限公司生产的深冷压力容器变形率数据,进一步优化深冷压力容器设计,有助于应变强化技术在深冷压力容器生产的工程应用。

高真空多层绝热超低温容器漏热分析

为解决高真空多层绝热超低温容器漏热的设计难点,通过对高真空多层绝热超低温容器支撑结构、容器接管、残余气体传热、辐射传热进行漏热分析,介绍了理论计算和数值模拟计算过程,同时提出了以机械构件和多层绝热结构优化为主的降低漏热的措施,最后将超低温容器蒸发率转化为允许漏热量,并以此作为性能考核指标,建立高真空多层绝热超低温容器漏热设计流程图,分析结果可为工程中的漏热设计提供参考。