Hyun-Wook Park

Fabrication of cables for the background-field magnet system of SSTF

The Korea Superconducting Tokamak Advanced Research (KSTAR) device has a fully superconducting magnet system consisting of 16 Toroidal Field (TF) and 14 Poloidal Field (PF) coils. For the test of the KSTAR cable-in-conduit conductor (CICC), an ambient magnetic field of /spl plusmn/8 T with a maximum change rate of 20 T/s is required and a background-field magnet system is being developed for the Samsung Superconductor Test Facility (SSTF). The CICC for PF1-5 is used as the conductor for background-field coils to check the validity of the PF CICC design. Two pieces of cables have been fabricated and the cable has the length of 870 m and the diameter of 20.3 mm. Pitches are 40, 80, 145, and 237 mm at each cabling stage. The void fraction of the CICC is expected to be more than 36%.

The test facility for the KSTAR superconducting magnets at SAIT

SSTF (Samsung Superconductor Test Facility) has been built with the primary goal of testing the KSTAR TF (Toroidal Field) and PF (Poloidal Field) magnets as well as CICC (Cable-in-Conduit Conductor) and superconducting strands in the most relevant manner. The facility is located at SAIT (Samsung Advanced Institute of Technology) near the KSTAR project home site. Two helium liquefiers of 120 liter/hr capacity have been utilized as refrigerators demonstrating simultaneous double mode operation of refrigeration and liquefaction. A forced flow supercritical helium cooling circuit allows the test facility to be operated at temperatures down to 4.5 K. Other major SSTF components are a large vacuum vessel (6 m diameter and 7.3 m height) with liquid nitrogen temperature shield, data acquisition and control system with EPICS (Experimental Physics and Industrial Control System), current leads, and 50 kA modular power supply with fast dump quench protection circuitry. SSTF has been used for the first test-phase of KSTAR CICC sample. The current status of SSTF as the KSTAR magnet test facility for components and qualification test is presented in detail.

The results of performance tests of superconducting wires for KSTAR magnets

The Korean Superconducting Tokamak Advanced Research device consists of 16 TF coils and 14 PF coils. All TF and PF coils are superconducting. Among them, 16 TF coils and 10 PF coils are made from Nb3Sn and the other 4 coils (PF 6 and 7, up/down) are made from NbTi. It is estimated that total 27 tons of Nb3Sn and 11 tons of NbTi are required for the fabrication of KSTAR magnets. The superconducting 8 mm rods are supplied by Mitsubishi Electric Corporation (MELCO) and Intermagnetics General Corporation (IGC) and processed to the final chromium plated 0.78 mm diameter strands by Nexans Korea and KISWIRE. Currently, about 6 tons of Nb3Sn strands have been produced, and the performance tests for them have been carried out. The specimens for the strand performance tests are taken from the both ends of the strand lot. In this paper, we present the latest test results of the current carrying capacity of non-copper volume, hysteresis loss of non-copper volume and residual resistivity ratio using statistical analysis.

Status of the KSTAR PF6 and PF7 coil development

The KSTAR superconducting magnet system consists of 16 TF (Toroidal Field) and 14 PF (Poloidal Field) coils. Both of the TF and PF coil systems use internally-cooled Cable-In-Conduit Conductors (CICC). The PF coil system, which consists of 8 coils in the CS (Central Solenoid) coil system and 6 outer PF coils, provides 17 V-s and sustains the plasma current of 2 MA for 20 seconds inductively. PF 1-5 coils use Nb/sub 3/Sn CICC in an Incoloy 908 conduit and PF 6-7 coils use NbTi CICC in a modified stainless steel 316LN(316LN+). The fabrication of PF7L/U & PF6L/U coils is completed at present. The engineering issues and fabrication process, which are related with the KSTAR PF 6-7 coil development, are presented and discussed in this paper. TF and PF coils are in the fabrication stage for KSTAR completion in the year 2006.