Research On The Slow Extraction Of Proton Synchrotron

Xi'an Proton Application Facility was built by Tsinghua University and Northwest Institution of Nuclear Technology,and was designed for the ground experiments for space irradiation effects.The design objective of XiPAF is to provide proton beam from 7MeV to 230MeV with a beam intensity of at least2×10¹¹ protons per pulse.To satisfy the requirements of irradiation experiment,the third resonant slow extraction and RF-Knockout technology was adopted.In this article,the resolution of accumulated dose was analyzed in terms of the requirements of proton single event experiments.The growth process of the particle's emittance and the transit time for extraction were explored by theory and simulation.The uniformity of extracted spill was studied in both the global extracted time?1¹0s?and single FM period?^ms?,and the method to improve the uniformity of extracted was raised:for the global extracted time,the uniformity can be improved by feedforward or feedback;for the sin gle FM period,dual FM method and synchrotron oscillation can be used to improve uniformity of the extracted spill.All these methods hav e been verified by the self-developed C++parallel program for slow extraction.When the strong space charge effect exists,the multi-stage-and-variable-rate extraction method was raised.And the uniformity of the extracted spill was improved significantly using this method.The separatrix of the stable region fluctuates during slow extraction due to power ripple,which causes uncontrollable spill and affects the extracted beam uniformity as well as the extraction efficiency.The influence of dipole and quadrupole power ripple on extracted spill was explored theoretically and simulated via TrackAll.According to a series o f simulation results,?I/Iset?120ppm for the QF power converter,?I/Iset?2000ppm for the QD converter and?I/Iset?400ppm for the dipole converter are acceptable.Since the power converters of the synchrotron in XiPAF satisfy the same standard in terms of power ripple,it is confirmed that?I/Iset should be limited to 100ppm for all power converters.