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Development of a Conduction-Cooled Low Temperature Superconducting (LTS) Pulse Coil

传导冷却低温超导 (LTS) 脉冲线圈的开发

基本信息

批准号：
16206028
负责人：
MITO Toshiyuki
金额：
$ 21.47万
依托单位：
National Institute for Fusion Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16206028/
关键词：
Superconducting Conduction cooling Cryogenic Pulse coil Momentary voltage drop SMES Power failure AC loss

项目摘要

A conduction-cooled LTS pulse coil has excellent characteristics, which are adequate for a short-time uninterruptible power supply (UPS). The conduction cooling has higher reliability and easier operation than the conventional cooling schemes such as pool boiling with liquid helium or forced flow of supercritical helium. A low AC loss and a high stability are required for the superconducting (SC) conductor. The SC conductor of a NbTi/Cu compacted strand cable extruded with an aluminum has been developed. The coil shape is a single solenoid of 183 turns x 14 layers wound on the GFRP bobbin. The Dyneema FRP (DFRP) spacers and the Litz wires (braided wires of insulated copper strands) are inserted in each layer. The DFRP spacers have a good thermal conductivity along with Dyneema filaments, which enhance the heat transfer from layer to layer in the windings. On the other hand, the Litz wires increase the heat transfer from turn to turn in the windings and enable conduction cooling of the … More coil by attaching the end of the Litz wires directly to the cold heads of the cryocoolers. The coil was connected with three GM cryocoolers which have cooling capacity of 4.5 W at 4 K and 240 W at 50 K. Whereas the coil cold mass is 1, 100 kg and the heat loads are 2.3 W at 4 K and 186 W at 65 K. It took approximately two weeks to cool-down the coil as exclusively utilizing cryocoolers. The spatial temperature distributions within the coil were negligible during the cool-down, which indicated good thermal properties of the coil. To evaluate the thermal performance of the coil, the coil current was reduced rapidly from the rated current of 1000 A with a time constant of 4 s. Due to the AC loss of 447 J, the temperature of the coil increased from 3.9 K to 4.4 K. However, the temperature increase of the coil was only 0.5 K. It means that the heat generated by the AC loss was well distributed within the coil winding and was also transferred to the cold heads of cryocoolers during a few second. Since the components of the coil have high thermal diffusivities at the cryogenic temperature below 10 K, the enhanced thermal diffusivity of the coil results in the rapid temperature stabilization. We have successfully developed the 1 MJ conduction-cooled LTS pulse coil. The high performance of the conduction-cooled coil has been demonstrated by the cooling and excitation tests and its applicability was also confirmed by the energy extraction tests as the UPS-SMES. Less

传导冷却的LTS脉冲线圈具有优良的特性，其适合于短时间不间断电源（UPS）。传导冷却比传统的液氦池沸腾冷却或超临界氦强制流动冷却具有更高的可靠性和更容易操作的优点。超导（SC）导体要求低的交流损耗和高的稳定性。研制了铝挤压NbTi/Cu紧凑绞合电缆SC导体。线圈形状是缠绕在GFRP线轴上的183匝x14层的单个螺线管。将Dyneema FRP（DFRP）垫片和绞合线（绝缘铜绞线编织线）插入每层。DFRP垫片具有良好的导热性，沿着Dyneema长丝，增强了绕组中层与层之间的热传递。另一方面，绞合线增加了绕组中匝与匝之间的热传递，并且使得能够对绕组进行传导冷却。 ...更多信息通过将绞合线的末端直接连接到低温冷却器的冷头上来形成线圈。该线圈与三台GM制冷机相连，GM制冷机在4K时的制冷量为4.5W，在50 K时的制冷量为240 W。而盘管冷质量为1100 kg，热负荷在4K时为2.3 W，在65 K时为186 W。它花了大约两个星期的时间来冷却线圈，专门利用低温冷却器。在冷却过程中，线圈内的空间温度分布可以忽略不计，这表明线圈具有良好的热性能。为了评估线圈的热性能，线圈电流从1000 A的额定电流以4 s的时间常数快速降低。由于447 J的交流损耗，线圈的温度从3.9 K升高到4.4 K。然而，线圈的温度升高仅为0.5K。这意味着由交流损耗产生的热量在线圈绕组内均匀分布，并且在几秒钟内也被传递到制冷机的冷头。由于线圈的部件在低于10 K的低温下具有高的热扩散率，线圈的增强的热扩散率导致快速的温度稳定。研制成功了1 MJ传导冷却低温超导脉冲线圈。冷却和励磁试验证明了传导冷却线圈的高性能，能量提取试验也证实了其作为UPS超导储能系统的适用性。少