The installation of a cryogenic circuit for a large-scale superconducting device such as a tokamak is quite complex. In the KSTAR tokamak, five cryogenic circuits are utilized to cool each type of the component (e.g., toroidal field magnets, poloidal field magnets, structures current leads, thermal shield, bus lines) independently. The circuit for the poloidal field magnets branches into hundreds of cooling channels. And five cryogenic valves control the flow rates according to the length of the cooling path. Ten cooling paths are arranged in parallel for cooling of the PF1 upper and lower magnets. The pressure drop is adjusted by a cryogenic valve with maintenance by a supercritical helium circulator. Although the flow rate should be uniform among the cooling channels but the flow imbalances was observed during flow tests at an individual magnets test. The flow rate should be uniform among the cooling channels but the flow imbalances observed during flow tests at an individual magnets test. The measured imbalance was around 10% between the KSTAR PF1 upper and lower magnets. To investigate the effects of the flow imbalance on the magnet temperature, a model of the PF1 upper and lower magnets system is developed using the SUPERMAGNET code. The maximum temperature trends are investigated depending on the flow imbalance.

中文翻译：

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流量不平衡对 KSTAR PF1UL 磁铁运行性能的影响

托卡马克等大型超导装置的低温电路安装相当复杂。在KSTAR托卡马克中，利用五个低温电路来独立冷却每种类型的组件（例如，环形场磁体、极向场磁体、结构电流引线、热屏蔽、总线线路）。极向磁场磁体的电路分支成数百个冷却通道。五个低温阀门根据冷却路径的长度控制流量。并联布置十个冷却通道，用于冷却 PF1 上、下磁体。压降由低温阀门调节，并由超临界氦循环器维护。尽管冷却通道之间的流速应该是均匀的，但是在单个磁体测试的流量测试期间观察到流量不平衡。冷却通道之间的流量应该是均匀的，但是在单个磁体测试的流量测试期间观察到流量不平衡。测得 KSTAR PF1 上磁体和下磁体之间的不平衡约为 10%。为了研究流量不平衡对磁体温度的影响，使用 SUPERMAGNET 代码开发了 PF1 上部和下部磁体系统的模型。根据流量不平衡来研究最高温度趋势。