We have designed a 500 A class high temperature superconductor (HTS) current lead using Bi2223/AgAu tapes for a conduction cooled superconducting magnet. The HTS current lead consists of two terminal blocks, a support tube, and seven Bi2223/AgAu tapes with support tapes. An operating condition is 500 A at 70 K, 0.6 T by conduction cooling, and heat leakage through the current lead is 0.32 W...
The superconducting joint technology used for high-temperature superconductors (HTS) is key for realizing persistent operation of HTS magnets. Recently we have succeeded in developing a superconducting joint between REBCO conductors using a polycrystalline intermediate, which has a critical current (Ic) of >100 A at 77 K [1]; A REBCO micro-polycrystalline intermediate was prepared on the...
This study presents the design and performance results of a pair of vapor-cooled MgB2 current leads for a 1.5 T MRI magnet developed by Kiswire Advanced Technology Ltd. in Korea. To reduce the liquid helium (LHe) consumption of the MRI system, the current leads were designed as a retractable type to be detached from the magnet operated under a persistent-current mode. From the cryogenic...
Within the frame of the R&D activities carried out in Europe for the Toroidal Field (TF) Coils of the nuclear fusion device DEMO, different proposals have been given so far. All of them rely on superconducting (SC) Low Tc wires (Nb3Sn). The present paper deals with a Wind & React solution based on Cable-In-Conduit Conductors (CICCs). The TF coil is a graded layer one, with varying SC, Cu and...
The High Field Magnet Laboratory has designed, manufactured and tested a pair of 20 kA binary vapour cooled/superconducting current leads for the superconducting outsert magnet of its 45 T hybrid magnet system, in close collaboration with the National High Magnetic Field Laboratory (FL, USA). The resistive section of each lead consists of 22 parallel copper plates cooled by a flow of nitrogen...
Superconducting high field magnets use the principle of superconductivity of the material, thus working with very high current density in thin cables. The cables are cooled down to cryogenic temperatures inside of a vacuum insulated cold box. In order to feed the high current into the cold box, it is important to cool down the conductors progressively. The less coolant is needed for current...
Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) was contracted by General Atomics Company to develop a superconducting feeder system containing a pair of 52 kA high temperature superconducting (HTS) current leads for ITER Central Solenoid (CS) magnet test. These HTS current leads are majorly based on the previous ITER lead design experiences. However, the vertical assembly...
In the framework of the French-German project Iseult, we chose to design the 4.5 K vapor cooled current leads of the 11.75 T MRI magnet using a burn-proof approach, i.e. they are able to withstand a 3-hour current slow dump without any active cooling. This constraint led us to select brass instead of pure copper, resulting in higher mass and thus in higher thermal stability. The drawback is a...
The MRI industry is reliant on persistent-mode superconducting electromagnets for high magnetic fields and increased stability. Achieving persistent coils is entirely dependent on the formation of high quality superconducting joints, currently made using Pb-Bi solder. Whilst this is an effective solution, there is legislative pressure to remove the lead even from medical instruments. There is...
The paper describes the result of the ITER feeder main busbar joint sample qualification test as confirmation of the requirement of busbar joint resistance; 2 nΩ at 70 kA at zero background field, as well as those of joint performance in various magnetic fields to investigate stability and current distribution characteristics in feeder-type joint box. The results support the quality of the...
The advent of new kind of superconductors can introduce a new application age. Modern magnet designs and applications push towards persistent mode system realized with multiple superconductive connected coils. The quality of field persistence is fundamental in order to characterize the goodness of the superconductive joint technical implementation. A theoretical methodology able to predict the...
Current leads with use of high temperature superconductors (HTS) permit to reduce sufficiently heat transfer to liquid helium in many superconducting magnets applications. They are one of the widest HTS applications. For example, in Large Hadron Collider more than 3000 units of such current leads are used providing sufficient saving of heat transfer to liquid helium. HTS current leads made of...
The Karlsruhe Institute of Technology (KIT) agreed to construct and test the High Temperature Superconductor Current Leads (HTS-CL) for the tokamak JT-60SA presently under construction in the frame of the Broader Approach agreement between Europe and Japan. In total 6 HTS-CLs for 25.7 kA for the TF coils and 20 HTS-CLs for 20 kA for the PF and CS coils are required and all of them have to be...
HTS superconducting magnets for MRI or NMR should be operated in persistent current mode to achieve high homogeneity and stability. A persistent current switch and a superconducting joint are the key technologies for persistent current operation. Recently, a superconducting joint has been fabricated successfully in Furukawa Electric Co., Ltd. We made a persistent current system including the...
The electrical interconnections between the LHC main magnets are made of soldered joints (splices) of two superconducting Rutherford cables stabilized by a copper busbar. In 2009, a number of splices were found not properly stabilized and could have burnt through in case of quench at high current. The LHC was therefore operated at reduced energy and all Rutherford-cable joints were...
Magnesium diboride (MgB2), which has a critical temperature (Tc) of 39 K, is a candidate for use in liquid-helium free magnetic resonance imaging (MRI). Since the discovery of MgB2, the performance of MgB2 wires and the manufacturing technology for long-length conductors have dramatically improved.Moreover, the superconducting properties of MgB2 wires have improved. Wires subjected to internal...