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Thermal-Engineering Stucy on Early Detection of Quench and Hyper Stabilization Method of Superconducting Coil

超导线圈失超早期检测及超稳定方法的热工研究

基本信息

批准号：
03452126
负责人：
AIHARA Toshio
金额：
$ 4.22万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452126/
关键词：
Superconductor Thermal Stability Immersion Cooling Forced Cooling Heat Transfer 超伝導体

项目摘要

The aim of this research project is to clarify thermal mechanism of quench in forced-and immersion-cooled superconducting coils, and to establish theory of thermal stability of superconducting coil, and to propose methods for early detection of the quench. The outline of the results obtained in this 3-year research project is given below.1. Numerical analyzes of quench mechanism and thermal stability of forced-and immersion-cooled superconducting coils were carried out. Various influences of governing factors on them were clarified quantitatively and the basic concept of early prediction of quench was established.2. Since the quench phenomenon is extremely rapid transient and indeterminate, and it occurs in a very strong magnetic field, it is almost impossible to predict the time and place of its occurrence. hence we propose two novel detecting methods : one is a film thermal sensor, and another is a visualization technique.Practical applicability of the film thermal sensor was examine … More d in an experiment on rapid transient boiling heat transfer of a pulse-heated strip in liquid helium. The data obtained in the experiment are also necessary for the precise analysis of the thermal stability. The test piece was a 20-mum-thick stainless steel strip, both surface of which were coated with PVF film and a carbon-paste film. This strip structure was to simulate an insulated superconductor in practical use and the carbon-paste film performed the part of an electric resistance thermometer. The heat-transfer data were reduced from the experimental raw values by numerical calculation considering the heat capacity and transient temperature distribution of the coating layrs : the obtained results had satisfactory accuracy to apply the film sensor to the early detection of quench initiation.As for a visualization technique of quench and its rapid propagation was investigated using a pancake-type superconducting coil immesed in liquid helium. It was found that the visualization technique will be a promising tool of the early detectin of quench ; however, we need further research to make applicatin of this charming technique to practical superconducting coils. Less

本研究的目的是阐明强迫冷却和浸没冷却超导线圈失超的热机制，建立超导线圈的热稳定性理论，并提出早期检测失超的方法。现将这项为期三年的研究项目所取得的成果概述如下。对强迫冷却和浸没冷却超导线圈的失超机理和热稳定性进行了数值分析。定量阐明了各种控制因素对它们的影响，建立了猝灭早期预测的基本概念。由于失超现象是非常迅速的瞬变和不确定的，而且它发生在非常强的磁场中，几乎不可能预测它发生的时间和地点。因此，我们提出了两种新的检测方法：一种是薄膜热传感器，另一种是可视化技术。对薄膜热传感器的实际适用性进行了…测试进一步介绍了液氦中脉冲加热板条的快速瞬变沸腾换热实验。实验中获得的数据也是精确分析热稳定性所必需的。试件是一块20微米厚的不锈钢带，其表面都涂有PVF膜和碳糊膜。这种带状结构是为了在实际应用中模拟绝缘超导体，而碳糊薄膜起到了电阻温度计的作用。考虑到涂层的热容和瞬时温度分布，通过数值计算从实验原始值中还原了传热学数据：将薄膜传感器应用于失超起始的早期检测，获得了令人满意的结果。至于失超的可视化技术，利用埋入液氦中的煎饼型超导线圈研究了失超及其快速传播。研究发现，可视化技术将是早期检测超导线圈失超的一种很有前途的工具，但要将这一迷人的技术应用于实际的超导线圈还需要进一步的研究。较少