Development of FAIR superconducting magnets and cryogenic system *

The first full size dipoles were built and tested [1]. These model tests show that the predictions established on Nuclotron model magnets are correct and thus the curved single layer magnet was the appropriate choice for the main dipole [2]. The generated AC losses were measured and a model built allowing calculating the expected loss of the dipole for any arbitrary cycle just with a few parameters [2]. Its predicted field quality matches the measured ones nicley. These results reassure that it is necessary to build the SIS100 main dipole based one a coil design with a high current cable and a single layer coil, which will provide the magnet with sufficient cooling power so that it will be able to provide even the triangular cycle [2]. This magnet has to be procured and tested. Prototype wires and cable pieces with a CuMn interfilamentary matrix were developed in frame of an INTAS project for the required high current Nuclotron cable [3]. An analysis of the source of the AC losses revealed that significant loss occurs in the nose of the stainless steel endplate, supporting the Rogowsky profile. A field analysis showed that the integral field strength non linearity is dominated by the non linearity of the B-H curve along the load line and thus a rectangular magnet end should be considered [2]. The high currenct cable, required for the main dipole, was used as basis for a 2 turn quadrupole design. This design allows constructing a G11 coil reinforcement structure and profiting from the R&D made for the dipole[2].