An underground remotely controlled cryopump vacuum system utilizing 460‐m long helium gas lines

摘要

A 1600 l vacuum chamber buried 300 m underground required a continuous operational vacuum of ≪1×10-6 Torr. Due to physics criteria, high gas load (2×10-2 Torr l/s), space limitations, harsh operating environment and reliability requirements, a cryopump vacuum system was designed to meet all design and operational requirements. The vacuum system consisted of downhole and uphole subsystems linked by 460 m long pressurized copper helium gas lines and control cables. The uphole subsystem consisted of the helium compressors, automatic control, and monitoring system. The downhole system consisted of the vacuum pumps and all related supported hardware necessary for long unattended remote operation. The design, installation, and operational requirements are reviewed and summarized for this initial and unusual application of remotely operated cryopumps.