R&D on joints between superconducting wires or tapes is one of the most important issues for the development of large-scale superconducting applications such as magnet, rotation machine and so on. Although the electro-magnetic properties between superconducting joints have been evaluated in several ways, the interfacial structure of the joint should also be investigated in order to sufficient...
Low resistivity joint technique for high-Tc superconducting (HTSC) tapes is one of the most indispensable techniques for practical applications. At the present time the solder joint technique is widely used for joining HTS tapes for the non-superconducting joint. However, in the case of a joint using a solder, the resistance across the joint cannot be very low because of relatively high...
The NUCLOTRON type cable has been chosen for developing a fast cycled superconducting dipole for the booster ring of the HIAF project at IMP. The splices of the cable are key components for the magnet. A design which has a resistance about 10-9 Ohm and is easy to be fabricated is developed. The structure of the joint is optimized with Opera software. And reliable fabrication process is...
GdBa2Cu3O7-δ (GdBCO) has high critical current density (Jc) of the order of 106 A/cm2 at 77 K in self-field and higher critical temperature (Tc) than that of YBa2Cu3O7-δ. Therefore, GdBCO coated conductor (CC) has been expected as a promising wire material. For the wire application, superconducting joint of CC has been required to lengthen them. In our previous work, superconducting joint of...
In this work we performed a series of measurements investigating both electrical and thermal contact resistance of YBCO stacks and cables for various surface preparation conditions. We explored the transverse resistance for sets of REBCO tape stacks, measured in a “through-the-stack” configuration. We also explored the ICR of YBCO cables under selected conditions. We analyzed these direct...
In REBCO tape having multi-layered structure, resistance of Cu/Ag and Ag/REBCO interfaces (interface resistance) is one of the major factors of joint resistance of tape-to-tape joints. Since the interface resistance depends on the manufacturer and/or lot number of REBCO tapes, it is necessary to evaluate the interface resistance beforehand at temperatures and magnetic fields of the operating...
The Nb3sn was prepared successfully by two methods of mechanical alloying followed by their respective heat treatment process. The microscope morphology, crystal structure, and superconducting properties were investigated. From the results, mechanical alloying was an effective method to produce the precursor, which changed the reaction formation energy of Nb3sn and can produce Nb3sn more...
The superconducting joint is one of key technologies to evolve high temperature superconducting (HTS) conductors and their applications. Various joint techniques have been proposed in these years [1]. To evaluate developed joint efficiently, we developed a resistance evaluation system for superconducting joints [2]. The system consists of a superconductor sample with a joint, a copper coil to...
Simply- and quickly-fabricated low-resistive joints between various high-temperature superconducting (HTS) tapes are needed for some cases in high-temperature superconducting (HTS) magnets such as nuclear magnetic resonance (NMR) magnets, nuclear fusion magnets, and so on. We have developed pressure welding with indium foil inserted between the joint surfaces at room temperature or with a...
Though low resistance joint is important technology for persistent current operation of HTS magnet system, superconducting joints of REBCO wires require direct epitaxial growth between REBCO surfaces that can only occur in high temperature procedure. On the other hand, at 4.2 K operation, even conventional solder spliced joints of coated conductors should have quite low joint resistance if low...
We are studding the superconducting joint between multi-filamentary Bi2223 tapes with incongruent melting (JIM) method, to develop a high-field 1.3 GHz-NMR in Japan. We obtained critical currents of 12 A at 77 K and 177A at 4 K for the reinforced HT-NX type wire in early stage of the study [1], and a high critical current above 50 A at 77 K was obtained in non-reinforced H type wire [2]. For...
In ITER magnet system, there are feeders for toroidal field (TF) coils, poloidal field (PF) coils, central solenoid (CS) modules, correction coils (CC), magnet structure cooling and monitoring instrumentation. Main busbar is used for TF, PF and CS feeders and corrector busbar for CC feeders. Main Busbar (MB) operated up to 68 kA with peak field of 3.6 T is used for TF, PF and CS feeders....
In recent years, magnesium diboride (MgB2) wire has become a promising candidate for the development of superconducting magnetic resonance imaging (MRI) magnets because of its critical temperature (39 K), which allows magnets to be operated without using liquid helium. Extensive research using unreacted MgB2 wire has enabled MgB2 MRI magnets to be operated in persistent current mode (PCM). We...
The next generation NMR spectrometer operated at 1.3 GHz (30.5 T) is currently being developed [1]. The superconducting magnet in this NMR consists of low temperature superconducting (LTS) coils using Nb-Ti and Nb3Sn, and high temperature superconducting (HTS) coils using Bi2223 and RE123, which are connected in series. Superconducting joints between Nb-Ti and Bi2223 are preferable to realize...
