Structure optimization and performance evaluation of CS CICC jacket based on N50H austenitic steel for future fusion reactor

Abstract

Fusion magnets are mainly wound by Cable In Conduit Conductor (CICC), therefore the cables can resist electromagnetic force under the protection of stainless steel jacket with higher yield strength. The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) has been designing a compact fusion device. As a structural component of CICC, the conductor jacket in Central Solenoid (CS) magnet withstands great electromagnetic force. Consequently, a higher strength stainless steel named modified Nitronic 50 (N50H) with Yield Strength (YS) > 1500 MPa @ 4.2 K is adopted to fabricate CS jacket. In this paper, the compressing process of CS conductors with the circle in square structure is simulated by finite element method. The results reveal stress concentration on the jacket after compression, and with the increase of the jacket’ corner radius, the compressing stress decreases, while the electromagnetic stress increases. Through the analysis, the suitable corner radius of the jacket is selected. Subsequently, the corresponding jacket is manufactured, and the tensile test is carried out at 300 K, 77 K and 4.2 K. The results show the existence of stress concentration and prove that the jacket achieves YS > 1500 MPa @ 4.2 K performance and meets the design requirements.