Modified Timing Circuit Of Streak Camera And Bunch Length Measurement In HLS Ⅱ

As an important measurement instrument,the streak camera is used to measure various characteristics and parameters of accelerators and storage rings during major accelerator facilities at home and aboard.In HLS storage rings,the streak camera is also used to measure parameters such as:bunch length,bunch longitudinal instability,bunch potential-well distortion,bunch transverse size.The streak camera provides a platform and instrument for various researches of storage rings as well as various reference measurements for stable operation of storage rings.Improvement on the basis of the existing streak camera and measurement of bunch length and potential-well distortion using streak camera are proposed in this paper.The quick-sweep frequency of existing streak camera is 102MHz.When measuring bunch longitudinal distribution,the streak image on the screen of the neighbor bunch will overlap from head to tail under multi-bunch pattern,so we cannot observe potential-well distortion.At the same time,it may lead to inaccuracy of bunch length measurement.Under single-bunch pattern,the overlap is still existed.Since this,we adjust the single delay so that two independent streak images are shown on the screen.In this paper,we designed a two-third frequency timing circuit to produce a single of 136MHz using RF frequency for input,and then used the circuit in the streak camera sweep modules.When working under this frequency,only one streak image is shown on the screen,and the head-tail overlap is inexistent.Besides,it improved measurement accuracy.This paper firstly introduced measurement methods of bunch longitudinal distribution and applications of streak camera,then introduced the structure,operating principle and measurement systems of streak camera in HLS II.Then we emphasized on the two-third frequency timing circuit for the trigger mode of streak camera,we used phase-lock loop chip ADF4360-8 from Analog Devices to achieve the frequency conversion.Then we designed the circuit schematic,PCB file,welded and test the circuit in the next.Besides,this paper also introduced longitudinal motion of bunch and the physics principle and mode of potential-well distortion in storage rings.In the end,we used the improved streak camera to measure bunch longitudinal distribution and potential-well distortion under single-bunch mode and multi-bunch mode in HLS Ⅱ.And then we compared the results to the measurement of the previous measurements to verify our design.