A high current RFQ （radio frequency quadrupole） is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is an important parameter when designing a ＆rod RFQ c...A high current RFQ （radio frequency quadrupole） is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is an important parameter when designing a ＆rod RFQ cavity, it reflects the RF efficiency of the cavity, and has a direct influence on the cost of the structure. Voltage distribution of a RFQ cavity has an effect on beam transmission, and particles would be lost if the actual voltage distribution is not as what it should be. The influence of cell length, stem thickness and height on shunt impedance and voltage distribution have been studied, in particular the effect of projecting electrodes has been investigated in detail.展开更多
In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a...In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator.The beam pipe of the kicker is a racetrack shape so as to avoid a transition part to the octagonal vacuum chamber.The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code.A higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement.Before the kicker cavity was installed in the storage ring,a variety of measurements were carried out to check its performance.All these results of simulation and measurement are presented.展开更多
文摘A high current RFQ （radio frequency quadrupole） is being studied at the Institute of Modern Physics, CAS for the direct plasma injection scheme. Shunt impedance is an important parameter when designing a ＆rod RFQ cavity, it reflects the RF efficiency of the cavity, and has a direct influence on the cost of the structure. Voltage distribution of a RFQ cavity has an effect on beam transmission, and particles would be lost if the actual voltage distribution is not as what it should be. The influence of cell length, stem thickness and height on shunt impedance and voltage distribution have been studied, in particular the effect of projecting electrodes has been investigated in detail.
基金Supported by Natural Science Foundation of China(11175173,11005105)
文摘In the upgrade project of Hefei Light Source（HLSⅡ）,a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator.The beam pipe of the kicker is a racetrack shape so as to avoid a transition part to the octagonal vacuum chamber.The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code.A higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement.Before the kicker cavity was installed in the storage ring,a variety of measurements were carried out to check its performance.All these results of simulation and measurement are presented.
