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Description
A 10-Mvar HTS synchronous condenser is under development, including a 36-slot air-core stator, and a 4-pole HTS rotor assembled by 12 REBCO double pancake (DP) coils. In this work, a scaled superconducting magnet prototype consisting of two DP coils was designed and fabricated before full manufacturing, which has an effective length of 300 mm and was wound by 5-mm wide REBCO tapes. To avoid delamination, these ReBCO coils are vacuum impregnated with paraffin instead of epoxy. And to enhance the mechanical strengthen, reinforcement structures and epoxy are applied between the coil surfaces and frameworks. The magnet prototype was conduction cooled by 5 bar, 20 K helium gas transmitted in copper pipes embedded in the magnet base plate. The experimental results show that the magnet can be effectively cooled to 21 K. Moreover, the magnet temperature remained stable for 1 hour during the continuous operation at the rated current of 250 A. The temperature distributions at different operation currents from 200 A to 270 A were also measured and compared to the simulation results considering heat loads from soldering parts and current leads. It was proved that the cryogenic and manufacturing solutions for the magnet prototype meet the requirements of the HTS rotor.
