Abstract
He refrigeration systems for the TRISTAN detector magnets were constructed for the Superconducting solenoid magnets that are used in high energy particle physics experiments at the TRISTAN e+e- collider. Three superconducting magnets and the He refrigeration systems (VENUS, TOPAZ and AMY) are situated at different locations around the 1km diameter TRISTAN ring. Therefore, the He refrigeration systems were designed such that they can be operated remotely from a central control station. Test operations of the He refrigeration system and magnetic field measurements were carried out between 1985 and 1986. By the end of July 1991, the total of cumulative operation hours reached 79, 000hrs (VENUS 28, 000hrs, TOPAZ 26, 000hrs and AMY 25, 000hrs). The failures for this long running period were analyzed and examined about the reliability of He refrigeration systems. The result of analysis was MTBF 909hrs and MTTR 6.7hrs. The availability became 0.993 by using those values. This shows that the He refrigeration systems have a high reliability.
