CRAFT TF中场线圈导体及内部接头电阻-温度特性研究

我国于2019年启动了国家大科学装置聚变堆主机关键系统综合研究设施(CRAFT)的建设，环向场(Toroidal Field, TF)线圈是聚变堆主机关键系统综合研究设施的重要组成部分.TF线圈绝缘制造采用真空压力浸渍工艺实现，因TF线圈体量巨大，为使线圈绝缘固化时温度均匀，减少绝缘树脂固化热应力，拟采用导体电流加热的方式进行加热.TF中场线圈有三个内部接头，因此需要同时知道导体和内部接头电阻与温度之间的关系，以防内部接头局部过热，导致绝缘固化失败.本文将中场内部接头样件加热到线圈绝缘工艺温度，用直流四线法测量导体和内部接头在不同温度下的电阻，得到在303～443 K温度区间内导体和内部接头电阻-温度关系式.发现相同温度下，导体电阻大于内部接头电阻，同时分析了内部接头铜套以及铬层对电阻的影响.并根据测得的电阻-温度关系式，可以得到在不同温度下超导缆及内部接头产生焦耳热的能力，从而为超导线圈绝缘固化温度控制提供重要的参考依据.

Research of the Resistance Characteristics under Insulation Curing Temperature of Conductor and Internal Joint for CRAFT TF Medium Fied Coil

In 2019, China initiated The Comprehensive Research Facility for Fusion Technology (CRAFT), of which Toroidal Field (TF) coils are an important part. The insulation of TF coil is manufactured by vacuum pressure impregnation process. Due to the huge volume of TF coil, to make the temperature of coil insulation solidification uniform and reduce the thermal stress of insulating resin solidification, conductor current heating is proposed. TF medium field coil has three internal joints, so it is necessary to know the relationship meanwhile between conductor and internal joint resistance and temperature. In case the internal joint may overheat locally, causing the insulation to fail to cure. In this paper, the internal joint sample of the central field is heated to the coil insulation temperature, and the resistance of the conductor and the internal joint at different temperatures is measured by DC four-wire method. The relation between the resistance of the conductor and the internal joint and the temperature change is obtained in the temperature range of 303 ~ 443 K. It is found that at the same temperature, the resistance of the internal joint is greater than that of the inner connector, and the influence of copper sleeve and chromium layer on the resistance of the internal joint is analyzed. According to the measured resistance-temperature relationship, the ability of superconducting cable and internal joint to generate Joule heat at different temperatures can be obtained, which provides an important reference for the temperature control of superconducting coil insulation curing.