Title :
Proposal of electrical edge joint for a demountable high-temperature superconducting magnet
Author :
Ito, Satoshi ; Hashizume, Hidetoshi ; Bromberg, Leslie ; Takayasu, Makoto ; Minervini, Joseph V.
Author_Institution :
Dept. of Quantum Sci. & Energy Eng., Tohoku Univ., Sendai, Japan
Abstract :
Electrical edge joint of a stacked high-temperature superconducting (HTS) conductor is explored for electrical joints for a demountable HTS toroidal field coil. Demountable coils would be very useful in small tokamak plasma-facing component-test machines, such as Vulcan. The demountable concept consists of forcing together the edges of stacked HTS conductor embedded in a conductive or a structural material. Numerical evaluation showed that inserting an indium film between joint surfaces or plating copper layer on joint surfaces could prevent joint resistance from increasing due to misalignment of the contact surface and would provide a compliant layer between joints. Joint resistance of the edge joint can become smaller than that of electrical lap joint when the number of the stacked HTS tape is large. We carried out a testing program of the edge joint of a stacked YBCO conductor within a copper jacket. The HTS cable has a critical current of 1600 A at 77 K in self field. The experimental results showed that joint resistance in the edge joint was higher than expectation, as was irreproducible. One potential reason for the degradation of HTS material is the damage to the tape edge in preparation of the joint region due to milling. Another potential reason was low accuracy of fabrication of joint surface, the joint surface were not parallel to another one. The joint resistance will be reduced by sophistication of fabrication process for the joint surface.
Keywords :
Tokamak devices; contact resistance; electrical contacts; fusion reactor instrumentation; fusion reactor materials; high-temperature superconductors; materials testing; plasma toroidal confinement; superconducting cables; superconducting coils; superconducting magnets; superconducting tapes; HTS cable; Vulcan; compliant layer; contact surface misalignment; copper jacket; copper layer plating; critical current; current 1600 A; demountable HTS toroidal field coil; demountable superconducting magnet; edge joint resistance; electrical edge joint; high temperature superconducting magnet; indium film; joint surface fabrication; joint surfaces; plasma facing component; small tokamak PFC test machines; stacked HTS conductor; stacked YBCO conductor; tape edge damage; temperature 77 K; Cooling; Insulation; Superconducting cables; Toroidal magnetic fields; Fusion reactors; high-temperature superconductors; power cable connecting; superconducting magnets;
Conference_Titel :
Fusion Engineering (SOFE), 2011 IEEE/NPSS 24th Symposium on
Conference_Location :
Chicago, IL
Print_ISBN :
978-1-4577-0669-1
Electronic_ISBN :
1078-8891
DOI :
10.1109/SOFE.2011.6052302