Development of cryogenic cooling system for the superconducting dipole magnet of the CBM detector.

The superconducting dipole magnet for the CBM detector is now under development at BINP. The CBM detector will be engaged in the research on compressed baryon matter at FAIR, Germany. The dipole magnet, which consists of two vertical superconducting coils, will produce a magnetic field of about 1.1 T in the center. The warm bore of the magnet is 1.44 m vertically. The total cold mass of the two coils is about 3.6 tons. The dipole magnet will be cooled by helium flows at 4.6 K@3 bar and 50 K@18 bar, supplied from a cryogenic plant. The cryogenic cooling system of the dipole magnet should provide the following operational regimes: controlled cooling down, cooling of the charged magnet at 4.5 K helium, quench recovery, and controlled warming up. The superconducting coils are serially connected to the cryostat with liquid helium at 4.5 K. The thermosyphon cooling regime will be realized for cooling of these coils.