Beam energy losses effecting particle dynamics in superconducting synchrotrons

Consideration is being given to the revealed effect of perturbation of synchrotron guiding magnetic field, due to strong effect of thermal state of superconducting (SC) cable on transport current distribution in it. The effect increases the possibility of particle leaving the region of stable phase oscillations. It rapidly developes in time due to the feedback of disturbance and losses and can result in beam destruction without magnet transition into normal state. The most rigid radiation conditions for SC coil (SCC) arrise during local with respect to aperture impingement of accelerated particles on vacuum chamber walls. In this case the inner SCC layers in angle opening on the order of 20 deg can be found in superheated state till the formation of restricted normal zone (RNZ). Curves of magnetic field distribution in aperture are given for dipole with saddle coil ''frame'' type with iron core type. It was assumed in calculations that transport current is absent in RNZ. Results of measuring local heating of SCC of ''frame'' type magnet with iron core