Study on the rate characteristics of the UNK superconducting dipoles

Results of investigating the dependence of transition current of superconducting (SC) models of the UNK dipoles to normal state on the rate of magnet current supply are presented. These investigations are caused by the necessity for providing stability of SC magnet operation both in the running UNK cycle and under accidental conditions during fast extraction of current from accelerator magnetic system. The greater part of investigations of rate characteristics was conducted with the use of short models with successive testing of obtained results with respect to full-scale SC magnets. Analysis of calculation and experimental results showed that application of SC cable with 8-10 mm spacing of fiber twisting and the value of transverse resistance between conductors of not less than 2X10-7 ΩXmm enables to elemenate the dependence of current of SC dipole transition to the normal state on the rate of current supply in 0-600 A/s range, including both running rates in the UNK cycle and possible rate of current change in magnets under accidental conditions