Beam lifetime of a synchrotron is dominated by Touschek scattering.In the beamline Phase II project of Shanghai synchrotron radiation facility,a passive third harmonic cavity is to be installed for bunch lengthening a...Beam lifetime of a synchrotron is dominated by Touschek scattering.In the beamline Phase II project of Shanghai synchrotron radiation facility,a passive third harmonic cavity is to be installed for bunch lengthening and instability suppressing.In this paper,the beam dynamics of the cavity is investigated.The parameters of passive operation are optimized to cancel the slope of RF voltage and lengthen the bunches.The Touschek lifetime increases are estimated for optimum and non-optimum voltage flattening.A tolerance of the operation is studied in case that there is a shift on detuning angle.The effect caused by reduction in harmonic voltage generated by lengthened bunch distribution is also estimated using iteration method.An increase in synchrotron frequency spread due to nonlinearity of the voltage giving to the bunch is found by using tracking simulation.This spread can help in damping coupled bunch instability through Landau damping.展开更多
Superconducting deflecting cavities can be used in synchrotron light source to generate subpico- second X-ray pulses while the impedance of the lower order modes(LOM)and higher order modes(HOM) in the cavity should be...Superconducting deflecting cavities can be used in synchrotron light source to generate subpico- second X-ray pulses while the impedance of the lower order modes(LOM)and higher order modes(HOM) in the cavity should be kept below an accepted level to avoid beam instability.These modes can be damped by adding waveguide on beam pipe.Detailed simulation of Q in CST Microwave Studio is introduced and experiment results on an aluminum model cavity with damping waveguide are reported to make a comparison.展开更多
基金supported by the National Key Research and Development Program of China(No.2016YFA0402001)
文摘Beam lifetime of a synchrotron is dominated by Touschek scattering.In the beamline Phase II project of Shanghai synchrotron radiation facility,a passive third harmonic cavity is to be installed for bunch lengthening and instability suppressing.In this paper,the beam dynamics of the cavity is investigated.The parameters of passive operation are optimized to cancel the slope of RF voltage and lengthen the bunches.The Touschek lifetime increases are estimated for optimum and non-optimum voltage flattening.A tolerance of the operation is studied in case that there is a shift on detuning angle.The effect caused by reduction in harmonic voltage generated by lengthened bunch distribution is also estimated using iteration method.An increase in synchrotron frequency spread due to nonlinearity of the voltage giving to the bunch is found by using tracking simulation.This spread can help in damping coupled bunch instability through Landau damping.
文摘Superconducting deflecting cavities can be used in synchrotron light source to generate subpico- second X-ray pulses while the impedance of the lower order modes(LOM)and higher order modes(HOM) in the cavity should be kept below an accepted level to avoid beam instability.These modes can be damped by adding waveguide on beam pipe.Detailed simulation of Q in CST Microwave Studio is introduced and experiment results on an aluminum model cavity with damping waveguide are reported to make a comparison.
