Fast Ramped Quadrupoles for the Transition Jump Scheme of the SIS100 Synchrotron of the FAIR Project
A gamma transition jump scheme has been developed for the heavy ion synchrotron SIS100 to modify the gamma transition during the acceleration of protons in such a way that the speed at which the relativistic gamma of the beam crosses the transition gamma is increased by two orders of magnitude. The transition crossing will be at gamma = 8.9, which corresponds to a kinetic proton energy of 7.4 GeV and a beam rigidity of about 28 Tm. The scheme employs fast-ramped quadrupoles with a ramping time of 0.5 ms from the maximum integral gradient of 0.4 T to the minimum integral gradient of minus 0.4 T. Each of the 12 fast ramped quadrupoles is embedded inside the cryostats of the so-called quadrupole doublet modules together with two main superconducting quadrupoles and one corrector magnet. The vacuum chamber, coils, and iron yoke are cooled with liquid helium. Nevertheless, the coils are made of standard copper tubes with a residual resistivity ratio of approximately 100 to avoid quench problems due to the fast ramping. The requirements and design of these normal conducting magnets inside the cryogenic environment are described.