  The Proton Improvement Plan-II (PIP-II) is a major upgrade to the Fermilab
accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency
(SRF) linear accelerator (Linac) powering the accelerator complex to provide
the world's most intense high-energy neutrino beam. The PIP-II Linac consists
of 23 SRF cryomodules operating at 2 K, 5 K, and 40 K temperature levels
supplied by a single helium cryoplant providing 2.5 kW of cooling capacity at
2.0 K. The PIP-II cryogenic system consists of two major systems: a helium
cryogenic plant and a cryogenic distribution system. The cryogenic plant
includes a refrigerator cold box, a warm compressor system, and helium storage,
recovery, and purification systems. The cryogenic distribution system includes
a distribution box, intermediate transfer line, and a tunnel transfer line
consisting of modular bayonet cans which supply and return cryogens to the
cryomodules. A turnaround can is located at the end of the Linac to turnaround
cryogenic flows. This paper describes the layout, design, and current status of
the PIP-II cryogenic system.
