The Development And Research Of The Beam Measurement System Based On Streak Camera

Dual axial streak camera plays an important of role in the measurement and diagnosis of beam and the accelerators at home and abroad. Beam measurement system developed based on streak camera provides an effective tool and research platform for accelerator physics research in HLS. Moreover, we make a serial of research of measurement and diagnosis of beam with the streak camera measurement system.The principle of operating modes of streak camera are described, including focus mode, single axial scan mode and dual axial scan mode. The hardware and software of streak camera are described in detail.The development of the front optical system of streak camera is made. According to the brightness of synchrotron light, the optical system is designed with using lens group to correct the aberration and transport the light and using narrow band filter to make the light monochrome for the measurement of high current. The optical system is designed with expanding the bandwidth of the input light to enhance the light intensity and eliminating the chromatic dispersion based on reflective optics for the measurement of low current. In order to pick a single bunch from multi-bunch, the pulse picking system based on Pockels effect is developed that is an effective means for the Bunch-by-Bunch measurements, the observation of beam instability and potential well distortions. The optical system is designed with using dove lens for the measurement of the transverse dimensions of bunch.The optical power control system is developed for the streak camera. The input optical power of the streak camera is detected with using Optical power detector. According to the light intensity measured, the neutral density filters is used to control the input optical power. The displacement of optical power detector and neutral density filters is moved with using the displacement platform. The communication between PC and the equipment of low level based on the network is designed to enhance the performance of anti-jamming in a strong electromagnetic environment.The timing system is developed for streak camera. In order to ensure the synchronization, the RF signal is divided to produce the clock trigger signal of subsystem. The broadband amplifier, attenuator and power splitter are used to control the amplitude of the clock trigger signal. The triggering pulse delay unit is developed for the measurement of the Bunch-by-Bunch. The performance of timing system is tested and the results show that the performance meets the requirements of the streak camera system.The theory related to the streak camera measurement is described, including the wake field, coupling impedance, the potential well effect, the longitudinal microwave instability and the beam instability caused by the RF cavity and wall impedance. According to the effect of potential well on bunch longitudinal distribution, the models of bunch longitudinal distribution are built due to inductance and resistance.The bunch longitudinal distribution as function of the inductance and resistance are determined with simulating. The physical image of oscillation modes is provided that corresponds with bunch longitudinal instability. The effect of RF phase modulation on the longitudinal dynamics and beam life time is described. The beam equation of motion is provided when RF modulation is applied, and the image of the bunch longitudinal dynamics is provided at different modulation frequencies. The effect of RF modulation on the bunch distribution and beam lifetime is described. The experiments related to the streak camera are based on the above theories.The experimental research is made with beam measurement system developed. In single bunch and multi-bunch mode, the experiments are done, including the bunch lengthening effect, the bunch length as function the RF voltage, the potential well effect, the bunch longitudinal oscillations. According to the bunch lengthening, the longitudinal broadband coupling impedance is determined. The Fast Fourier Transform (FFT) is used to analyze the bunch oscillation frequency from the bunch oscillation images synchronously and verify the longitudinal oscillation mode of the beam. The experiment of the effect RF phase modulation on the bunch life and longitudinal dynamics of bunch is made and the results show that RF phase modulation influence the bunch longitudinal distribution and extend the beam lifetime. The transverse size of the bunch is measured. Finally, the measurement of the laser pulse shaping is made with the streak camera.This subject is supported by the National Natural Science Foundation Project (11175173) and of the innovative projects of Chinese Academy of Sciences.