Cryogenic technologies of the Nuclotron (superconducting relativistic nuclear accelerator)

Abstract

The Nuclotron is the first superconductingsynchrotron intended for the acceleration of high- energy nuclei and heavy ions. The accelerator is designed to provide beams of relativistic particles with energies up to 6 GeV per nucleon. The accelerator was put into operation five years ago at the Joint Institute for Nuclear Research in Dubna near Moscow. The cryogenic system of the Nuclotron includes three helium refrigerators. Each of them has a nominal capacity of 1600 W at 4.5 K. These refrigerators cool the accelerator ring, which has a perimeter of 251.5 m and a “cold” mass of about 80 tons. The ring of the Nuclotron comprises 96 dipole magnets 1.5 m long and 64 quadrupolelenses 0.45 m long. The magnetic field of about 2 T is configured with a “cold” iron yoke and a hollow superconductor inside which the two-phase helium flows. There are 28 correctors 0.31 m long with three or four types of windings in each, twelve 6 kA helium-cooled current leads, 234 leads of 100 A current for correcting windings, and also about 600 sensors of cryogenic temperatures. The experience of using novel technical solutions in the design of the Nuclotron cryogenic system is described.