Improvement on Superconducting Magnet Performance using Fountain Effect of Superfluid Helium

利用超流氦喷泉效应改进超导磁体性能

基本信息

批准号：
12650193
负责人：
OKAMURA Tetsuji
金额：
$ 2.3万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Heat transport characteristics of superfluid helium (He n) in channel segmented by different types of spacer having several holes have been investigated on the basis of both experiment and numerical analysis. The heat transport performance has been examined for the following spacers : (a) FRP spacer without any hole, (b) FRP spacer with several holes of 2 or 4 mm diameter, (c) porous spacer made of fine powder of sintered Al_2O_3, (d) porous spacer made of high density polyethylene (HDPE) which is more flexible than Al_2O_3. The average diameter of the porous is about 1μm. It is expected that helium flow is induced in the channel because of a fountain effect when the porous spacer is applied.The λ-transition heat flux when we use the spacers having holes of diameter 2 mm and 4 mm is almost the same. This value is about 1.5 times larger than that in the case of using spacer without any hole. The λ-transition heat flux depends on the porosity of the spacer. A relatively high cooling performance can be realized when the porosity is only about 5%. These results lead to the understanding that the introduction of some holes in the spacer is a very effective way to suppress local temperature rise in the He II channel.The λ-transition heat flux increases remarkably when the porous spacer is used instead of the FRP spacer with holes of 2 or 4 mm in diameter, because Hen flow is induced in the heated channel by a fountain effect. It is also found that the use of porous spacers between Hell channels is effective to suppress a steep temperature rise in the heated channel not only when the channel is filled with He II entirely but also when normal helium (He I ) is generated in the channel.

基于实验和数值分析，已经研究了由具有多个孔的不同类型的间隔者分割的通道中超流体氦（HE）的热传输特性。已经检查了以下间隔仪的热传输性能：（a）没有任何孔的FRP垫片，（b）直径为2或4 mm的几个孔的frp间隔器，（c）由烧结的Al_2O_3的细粉末制成的多孔间距，（d）由高密度的高密度多乙烯（HDPE）制成的，比Al_ 2 cold_2。多孔的平均直径约为1μm。预计当施加多孔间隔物时，由于喷泉效应会产生氦气流量。当我们使用具有直径为2 mm和4 mm的垫片时，λ变换热通量几乎相同。在使用没有任何孔的垫片的情况下，该值大约是使用垫片的1.5倍。 λ变换热通量取决于垫片的孔隙率。当孔隙率仅约5％时，可以实现相对较高的冷却性能。这些结果使人们了解到，在间隔器中引入一些孔是抑制He II通道中局部温度升高的一种非常有效的方法。当使用多孔间隔者而不是直径为2或4 mm的孔孔时，λ递交热通量会显着增加，因为直径为2或4 mm，因此，由于热通道在热通道中诱导了母鸡的流量，因此受到封闭的效应。还发现，地狱通道之间的多孔间隔剂的使用有效地抑制加热通道中的钢温度升高，不仅是当通道完全填充He II时，而且在通道中产生正常的氦气（HE I）时。