Development Of Multi-channel Weak Current Measurement System And Application In Beam Diagnosis

With the wide application of accelerator devices in scientific research and radiology,as "eyes" of accelerators,beam diagnostic systems is increasingly playing an important role.Especially in materials irradiation and modification and surface physics experiments,the measurement of beam's profile and intensity distribution is critical.This work builds a multi-channel weak current measurement system,including multi-channel weak current amplifier and a data acquisition system based on LabVIEW,which all can be used for various applications of beam diagnostic applications.The multi-channel weak current amplifier is based on instrumentation amplifier circuit.According to signal source,single-ended input and differential input PCBs are designed.The test results show it has good linearity,strong anti-interference ability and high resolution rate and other advantages.Besides,this paper completes the compilation and debugging of the data acquisition system and image inversion program independently with the help of LabVIEW.Based on the weak current measurement system developed in this paper,different probes can be designed to meet different experimental requirements.In this paper,three modes of probe schemes are designed,which are transmission mode,full-block mode and scanning mode,respectively.The first one is the 120 cross-wires grids probe,achieving the beam profile monitoring.The second is a two-dimensional position sensitive anode probe,which can make up for the low blocking rate,limited energy range and other shortcomings of the first probe.The third is a 128-channel Faraday tube array probe that provides a measure of the profile and intensity distribution of steadystate or quasi-steady-state beams with more accurate accuracy and higher position resolution.Besides,a high power ion implantation platform for measuring the divergence of the beam is designed,including the workbench components,the drive control module,the beam divergence measurement module.To deal with the energy accumulation due to the strong current beam,this paper completed finite element thermal analysis and attempted design of the cooling waterway.