Structural Analysis and Fatigue Test of Helium Inlet for EAST PF Coil

Abstract

The operating temperature of the EAST PF coils is 4.5 K which are cooled by supercritical helium through a helium inlet located at the jacket. The leakage was occurred in one PF helium inlet after the steady operation of EAST for 12 years. The finite element model of PF helium inlet is established and the structural analysis is performed. The static assessment shows that thermal load and G11 enforced displacement are the main causes of weld failure. PFhelium inlet is only subjected to the cyclic electromagnetic force under normal circumstances, which is designed to withstand 2e5 cycles at 4.5K. The FEM results show that the helium inlet on PF coil can bear the electromagnetic force during the service life. The fatigue test was performed on a full-size sample with a double strain range of at 4.5 K, and the fatigue specimen was fractured at 24570 cycles at the clamp welding region. The lifetime of the helium inlet can withstand more than 2e5 cycles, which is met the test required cycles. Therefore, the good structural performance of the PF helium inlet which can meet the EAST design requirements, and it can be fabricated for prototype coil applications.