The measurement and control system for 920 MHz NMR magnet

After the successful test at the Takasago factory of Kobe Steel Ltd (KSL). 920 MHz magnet was transported and installed in Tsukuba Magnet Laboratory (TML), NIMS in April, 2002. To achieve a quick energization and long term operation with a minimum number of operators, the cryostat was equipped with an automated control and monitoring system. During the cooling process below 4.2 K and the energization procedure up to 21.6 T, the temperature of the magnet and He II bath was controlled automatically. Since the all installation procedure has completed in July 2002, the magnet has been continuously cooled to 1.545 K and the temperature variation has been kept within 0.01 K for over a year.