The KSTAR PF cryogenic circuit is cooled by the supercritical helium in a forced flow. A unique feature of the poloidal field (PF) is that the cryogenic inlets and outlets… Click to show full abstract
The KSTAR PF cryogenic circuit is cooled by the supercritical helium in a forced flow. A unique feature of the poloidal field (PF) is that the cryogenic inlets and outlets of the PF1 ∼ 4 upper and lower (UL) coils were located inside the coil in a zone with large magnetic field variation. As a result, the major heat load produced by ac losses is localized at both the inlets and outlets, so that a drastically reduced or even no temporal cryogen flow is frequently observed at the inlets of the PF1 ∼ 4UL coils. This kind of temporal blockage of the cryogenic loop can seriously affect the thermo-hydraulic analysis of the superconducting magnet system. Understanding the dynamic behavior of the flow affected by ac losses is one of the keys to ensuring operational stability. Therefore, a full KSTAR PF cryogenic loop was developed using the SUPERMAGNET code to investigate dynamic thermo-hydraulic behavior. The numerical simulation results were also compared to the experimental data of the PF1 magnet test, in which the current is applied from 15 to –15 kA.
               
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