Uniformity Control of Scanned Beam in 300 MeV Proton and Heavy Ion Accelerator Complex at SESRI

In recent years,heavy ion accelerator technology has been rapidly developing worldwide and widely applied in the fields of space radiation simulation and particle therapy.Usually,a very high uniformity in the irradiation area is required for the extracted ion beams,which is crucial because it directly affects the experimental precision and therapeutic effect.Specifically,ultra-large-area and high-uniformity scanning are crucial requirements for spacecraft radiation effects assessment and serve as core specification for beamline terminal design.In the 300 MeV proton and heavy ion accelerator complex at the Space Environment Simulation and Research Infrastructure(SESRI),proton and heavy ion beams will be accelerated and ultimately delivered to three irradiation terminals.In order to achieve the required large irradiation area of 320 mm×320 mm,horizontal and vertical scanning magnets are used in the extraction beam line.However,considering the various requirements for beam species and energies,the tracking accuracy of power supplies(PSs),the eddy current effect of scanning magnets,and the fluctuation of ion bunch structure will reduce the irradiation uniformity.To mitigate these effects,a beam uniformity optimization method based on the measured beam distribution was proposed and applied in the accelerator complex at SESRI.In the experiment,the uniformity is successfully optimized from 75%to over 90%after five iterations of adjustment to the PS waveforms.In this paper,the method and experimental results were introduced.

Alignment technology of heavy ion medicalmachine

Background Heavy ion medical machine(HIMM)is built by the Institute of Modern Physics,Chinese Academy of Sciences,with a high-energy beam transport line with a height of 18 m,and its complex space mounting structure increases the difficulty of installation and alignment.Purpose The aim of this paper is to provide methods to install all accelerator components efficiently and to ensure that the alignment accuracies of all installed components are within the designed values.Methods We accomplished the fiducialization and pre-alignment of complex modules by combining the laser tracker and the alignment telescope.By analyzing various elements that affect the accuracy of alignment,a method of alignment for high-energy beam transport line was proposed based on high-precision three-dimensional control network.Results All components have been installed and aligned in a short time,alignment position accuracy of magnets is less than 0.1 mm,and the treatment components alignment accuracy is no more than 0.4 mm.Conclusions On the basis of error analysis,all alignment results are better than the required precisions,and all of these guaranteed the successful operation of HIMM.