Investigation of orthogonal experiment for fabrication of soldering joint for a 4 T HTS coil

Joining process of individual BSCCO conductors is inevitable; because the double pancake coils need to be connected with each other. Since the resistance characteristics of joint can affect the stability of NMR system seriously, we did a research on soldering joint in this work. As resistance characteristics of soldering joint can vary with conditions such as joint length, thickness, temperature and so on, we conducted short sample joint experiments with orthogonal experimental design. The significance of each condition's influence was calculated quantitatively, andan appropriate soldering condition was put forward, under which the lowest joint resistance can be obtained. We also applied this appropriate soldering condition to fabricate joints for a 4 T HTS coil and tested its practical electrical properties.