Commissioning Test Results of Variable-Temperature Helium Refrigerator/Liquefier for NIFS Superconducting Magnet Test Facility

Abstract

The superconducting magnet test facility in the National Institute for Fusion Science has been upgraded for excitation tests at a wide temperature range and a higher magnetic field of 13 T. As part of the upgrade, the helium refrigerator/liquefier operated for 24 years was replaced with a variable temperature helium refrigerator/liquefier. The required liquefaction rate is 250 L/h and the required refrigeration capacity is 600 W at 4.5 K as the previous one. Besides, it has a new feature that can supply helium gas of a wide temperature range. The typical design cooling capacity is 1 kW under the condition of 20 K supply/30 K return and 1.5 kW under the condition of 40 K supply/50 K return. After the replacement, a series of commissioning tests were performed under the various operational conditions.From the results, the satisfactory thermodynamic performance was confirmed. In the future, it is expected that the substantial progress will be made in the development of large scale superconducting magnets with advanced superconductors such as high temperature superconductors and MgB2.The design of the variable temperature helium refrigerator/liquefier and the results of the commissioning tests are reported in detail.

Self-field measurements of an HTS twisted stacked-tape cable conductor

“…Energization tests of the sample were conducted using the 13 T test facility of the National Institute for Fusion Science (NIFS) [11,12]. The sample was installed into a vacuum vessel located in a bore of an external field coil.…”

Overview of Fusion Engineering Research in Japan Focusing on Activities in NIFS and Universities

“…A large bore (700 mm in diameter) and high field (13 T) magnet test facility 15 , a 9-T split coil, 75-kA DC power supply, and temperature-variable (4-50 K) refrigerator 16 have been installed for testing various superconducting conductor and coil samples. These facilities have been used for testing the performance of short HTS conductor samples 17 , the ITER-TF joint samples 18 , and the JT-60SA CS model and module coils 19 .…”

“…High temperature superconducting magnet 13 T, φ700 mm Solenoid Coil 15 , 9T Split Coil, Temperature Variable Refrigerator 16 Short HTS sample tests 17 ITER-TF Joint Sample tests 18 JT-60SA Central Solenoid tests 19 Blanket…”

Investigation of long time constants of magnetic fields generated by the JT-60SA CS1 module

“…[6,7,10,11]. The helium cryogenics system of the test facility was upgraded in the 2014 Japanese Fiscal Year [12]. Fig.…”