Study And Design Of The Stripline Nanosecond Kicker

Synchrotron radiation source is one of the most important tools in many basic disciplines It has developed to the fourth-generation light source which is close to the diffraction limit.In order to reduce the beam emittance,high gradient quadrupoles and high strength sextupoles are used in the design,which greatly increases the nonlinear effect,resulting in the reduction of beam dynamic aperture,and the traditional off-axis convex rail injection method will not be applicable.Longitudinal accumulation injection scheme and swap-out injection scheme are on-axis injection method,which have low requirements for dynamic aperture and can meet the characteristics of diffraction limit storage ring.In this kind of injection method,the stripline kicker is the key component.Hefei Advanced Light Facility(HALF)proposed by the National Synchrotron Radiation Laboratory(NSRL)is a fourth-generation light source based on the diffraction limited storage ring.At present,the pre-research work is in progress,and the off-axis injection and on-axis injection schemes are in the pre-research range.This paper mainly introduces the design and research of the stripline kicker applied to the longitudinal accumulation injection scheme of HALF.The principle of on-axis longitudinal accumulation injection is analyzed,and the technical requirements of the longitudinal injection scheme for the nanosecond stripline kicker are given.On the basis of the existing literature,the time sequence diagram used to study the relationship among kicker,bunch and high voltage nanosecond pulse is improved,and a more perfect time sequence relationship between bunch and nanosecond pulse in the storage ring in the longitudinal accumulation injection scheme is obtained.The relationship between the electrode length of the kicker and the shape and amplitude of the high voltage pulse is deduced.According to the transmission line theory,this paper introduces the working principle of the nanosecond stripline kicker,summarizes the various modes of the stripline kicker and their naming method.Introducing the relationship between the characteristic impedances in different modes.CST is used to design the stripline kicker which is applied to the HALF longitudinal accumulation injection scheme.The performance of the stripline kicker is analyzed in terms of S-parameters,characteristic impedance,field uniformity,maximum field strength and beam coupling impedance.This paper introduces the processing scheme and installation process of the prototype.The transmission and reflection parameters of the prototype are measured by the network analyzer,which is in good agreement with the simulation results.TDR module of network analyzer is used to test the impedance of stripline kicker,which is consistent with CST simulation results.Using the bipolar high voltage nanosecond pulse generator,the pulse transmission test of the kicker is carried out.The results show that the kicker has good transmission characteristics,with small amplitude attenuation,waveform distortion and reflection,which verifies the rationality of the design.According to the test results of the first-generation prototype,the optimized improvement is proposed.The special customized vacuum connector is used to realize the connection with the electrode and improve the performance of the kicker.The loss factor and beam coupling impedance of pulse kicker are simulated,and a novel impedance matching section with the function of tightening measuring line is designed.When measuring the longitudinal beam coupling impedance of the impactor,the problem of installation and tension of the measuring line is effectively solved.Finally,the longitudinal beam coupling impedance of the kicker is tested.