Analysis on the contact force behaviors among strands of CICC conductor cross section

Abstract

International Thermonuclear Experimental Reactor (ITER) hopes to achieve controllable thermonuclear fusion by constraining the motion of high temperature plasma by a strong magnetic field which is generated by superconducting magnets wound by the cable-in-conduit conductors (CICCs). The CICC structure is complex, usually with thousands of NbTi/Cu or Nb3Sn/Cu twisted in four or five stages. It operates in a complex environment of extremely low temperature, high current and strong magnetic field. The electromagnetic force generated by the superconducting material will cause deformation, reduce its characteristic parameters and bring hidden trouble to the safety of the device. Traditional studies on the contact force of the cross-section strand of CICC mostly adopt non-actual object photoelastic model in the experiment, and numerically adopt discrete element method (DEM) without particle deformation. However, it is difficult to give the contact force of the cross-section strand closer to the real working condition. In this experiment, the deformation characteristics were calculated between strands of the prototype of CICC by spraying speckle on the cross-section and using digital image correlation (DIC). Theoretically, taking the strand deformation obtained by DIC as the input parameter of granular element method (GEM), the distribution characteristics of the contact force of the CICC conductor under the action of transverse pressure are calculated, and the size and direction of the contact force chain are statistically analyzed.