Study on unsymmetrical phenomena of vapor cooled current leads

Unsymmetrical phenomena of gas flow and temperature distributions between a pair of vapor cooled current leads (VCCL) often occur in superconducting systems, which makes the VCCL depart from the optimum operating status, consequently results in an increased heat leak to the cryostat and even a destroyed safety operating condition of the VCCL. To analyze this problem, a numerical model for the VCCL was built, which is based on the conservation equation of energy for the solid and the conservation equations of mass, momentum, and energy for the fluid. With this model, unsymmetrical phenomena between a pair of VCCL were analyzed. Unbalanced gas flow distribution in a single multi-channel VCCL was also studied. Some conclusions were made for the design of VCCL, and a new type of VCCL with combined positive and negative poles and a helical cross section structure was developed. Test results showed that the unsymmetrical phenomena can be well restrained by using the new type of VCCL.