Operation of the Tevatron Six-Kilometer-Long Transfer Line

The Tevatron transfer line consists of twenty-six 250-meter sections interconnected with vacuum jacketed U-tubes forming a loop. Each section carries a supercritical helium line and a subcooled liquid nitrogen shield with an expansion joint in the middle of the run. The Tevatron refrigeration system is based on the concept of a Central Helium Liquefier providing liquid to twentyfour satellite refrigerators operating as amplifiers with a flow gain of 12 and providing 966 watts per unit. Both from the standpoint of system reliability and ease of installation, debug and startup, it was decided to build a complete transfer line loop starting at the Central Liquefier and returning to it. This loop consists of twenty-six independent sections; each is interconnected to the next by a pair of vacuum jacketed U-tubes with a branch tap to the local refrigerator. This system permits the loss of any one section and still maintains all twenty-four refrigerators operating by feeding a portion of the loop in reverse. This report describes the cross section of the transfer line, the expansion and bayonet cans at each end, and the U-tubes which connect the various sections and provide branch taps to the refrigerator and magnet systems, as well asmore » other minor components of the cooling system. Specifications, materials, and schematics are provided.« less