Nitrogen Cryogenic System For The Nica Accelerator Complex At Jinr

The Nuclotron-based Ion Collider fAcility (NICA) accelerator complex is scheduled to be put into operation in full configuration in 2023 at JINR. This facility comprising the existing Nuclotron together with two newly created superconducting accelerators-booster and collider-will require additional refrigerating capacity at 4.5 and 77 K. The helium cryogenic system of the NICA complex will be constructed as a result of the modernization of the existing equipment for cryogenic supply of the Nuclotron, but the liquid nitrogen plant will be completely new. It will be based on a 1300 kg/h nitrogen liquefier and two 500 kg/h recondensers of nitrogen vapors. This report describes the schematic diagram of the system of liquid nitrogen that will be used for refrigerating the thermally insulating shields of the cryostats at 77 K and at the first stage of cooling down three accelerator rings with the total length of about 1 km and the "cold" mass of 290 t. We demonstrate the status and recent development of the nitrogen cryogenic system: location, basic parameters, and design of major components and discuss their phased commissioning.