The Design Of Strip-type Beam Position Detector Under High Repetition Frequency Conditions

Beam position Monitor is the significant device for beam diagnostic,which analyze the electromagnetic field excited in the detector by the beam to calculate the character of the beam transvers position in the accelerator pipe,bunch length,beam charge.Beam position monitor was widespread used in the large scientific research equipment such as Accelerator,FEL(Free-Electron-laser),Synchronous light source.In order to provide a higher quality beam,the operation frequency of the accelerator is constantly rising,and the interval between the bunches is gradually reduced,which ask higher requirements on the beam diagnostic technology.This paper introduces the beam position monitor for X-band FEL,witch has the pulse repetition frequency of 434MHz,and the minimum interval between bunches is 2.3ns.In order to detect the transverse position of the bunch,a strip-type beam position monitor(Stripline-BPM)was designed.Because of the shorter interval distance between bunch-to-bunch,the signal generated by the fomier bunch in the detector will reflection on the electrode which lead to a interference measurement,so the process of reducing signal reflection is perfonned when the detector is designed.The paper first introduces the different types of beam position monitor,and compares them between different kind of device.It shows although the measurement accuracy of stripline-BPM is not superior as current popular cavity BPM.However,it has the less effect by the wake field,the signal-to-noise radio of detect is better,and also the strip type BPM is relatively simple to design and processing.Secondly,the optimal design of the Stripline-BPM is earied out.The measurement sensitivity and resolution of the designed detector are calculated.The final results shows that the Stripline-BPM has a good application prospect in the front section of the accelerator with the low particle energy,and the work of this paper has certain guiding significance for future processing and testing of the detector.Finally,the design of the model is summarized and discussed,analyze the existing problems meanwhile point out the direction of optimizing the design in the future.