Research On Key Technology Of Permanent Magnet Spread Device Of 1 MeV Electron Irradiation Accelerator

Since the birth of nuclear technology in the early 20 th century,it has developed rapidly and been gradually applied to various fields of national economic development,and irradiation technology is an important component of it.The magnetic scanning system of the traditional electron irradiation accelerator is an electromagnet.Although the adjustment and control are convenient and the technology is mature,the electromagnet cannot solve the problem of "tail sweep" and the abnormal beam spot.It is necessary to adjust the power supply waveform to match the conveyor speed to ensure the uniformity of the irradiation.If the magnet power supply fails,it will cause the titanium film to burn and damage the quality of the irradiated product.In serious cases,the accelerator will be shut down.The permanent magnet beam spread device studied in this paper has advantages of direct electron beam diffusion,the improvement of irradiation uniformity,the expansion of irradiation area,good protection of titanium film and suitable irradiation for large-size different components.The beam simulation and accelerator test verify the engineering application feasibility of the beam spread device.In this paper,it is based on the principle that the beam is focused in one direction and defocused in the other direction of the standard quadrupole iron.By analyzing the beam focusing and defocusing characteristics,the special quadrupole and octupole magnetic field was constructed.The quadrupole magnet will spread out the electron beam,and the octopole magnet shapes the spread electron beam.By using Maxwell and Parmela,the electromagnetic field calculation and beam dynamics simulation were carried out.The general adjustment rules of the device were summarized,which include rules of the size of a single quadrupole magnet or a single octopole magnet,rules of the distance between two magnets and the spread rules of different distribution electron beams.In this paper,the simulation of electron beam diffusion was carried out.The point scanning is replaced by the irradiation of beam diffusion.Whether the special magnetic field can meet the requirements of electron beam direct diffusion was verified,and the irradiation uniformity was calculated.The magnetic field measurement which includes the screening of the magnetic field uniformity of the pole,and the overall magnetic measurement after the installation of the device was carried out.Finally,combined with the beam dynamics simulation of the beam spread device,the engineering verification of the beam spread device was carried out on the 1Me V electron irradiation accelerator.