Prototype Design of External Bypass for ITER Poloidal Field Converter

This paper describes the prototype design of an external bypass that provides protection for the ITER poloidal field converter and magnets in fault conditions. The maximum peak pulse current of the bypass will reach to about 350 kA in the worst case. Three kinds of arm structures are compared according to the design requirement and the specific circumstances of branches. The structure, whose current flows in and out on the same side, is selected and combined with the installation and location. The external bypass structure model is analyzed and compared through analytical and numerical methods. Then a 3-D numerical model of an electromagnetic field is established based on Maxwell. Now a full prototype has been manufactured by China, and the dynamic stability test of the prototype has also been accomplished successfully. It shows that the prototype design can fully satisfy the design requirement and the reliability has been improved.