The SNS superconducting linac system

The SNS has adopted superconducting RF technology for the high-energy end of its linac. The design uses cavities of β=0.61 and 0.81 to span the energy region from 186 MeV up to a maximum of 1.3 GeV. Thirty-three of the lower β cavities are contained in 11 cryomodules, and there could be as many as 21 additional cryomodules, each containing four of the higher β cavities, to reach the maximum energy. The design uses a peak surface gradient of 35 MV/m. Each cavity will be driven by a 550 kW klystron. Cryomodules will be connected to the refrigerator by a pair of "tee" shape transfer lines. The refrigerator will produce 120 g/sec of refrigeration at 2.1 K, 15 g/sec of liquefaction at 4.5 K, and 8,300 W of 50 K shield refrigeration