Studies On The Generation And Transmission Of High Current Single Charge Ion Beam

With development of nuclear physics and nuclear technology,the demand for high current、high power accelerators has become increasingly strong,which has greatly contributed to the development of high current accelerators.In the case of high current accelerator technology,the study of ion source and beam transport in low energy is critical.For example,in the rapid development of ADS(Accelerator Driven Sub-critical System)accelerator technology,the acquisition of high-quality proton beam,the high-performance transmission and the coupling to the accelerator are a difficult and critical link.In this paper,a low energy transmission line with an analyzing dipole is designed for the requirements of Jinping Underground Laboratory for Nuclear Astrophysics(JUNA),which will be the world’s leading deep nuclear astrophysical experimental device.JUNA accelerator project needs a high current ion source and LEBT to provide 10 mA of H~+,He~+,and 5mA of He2~+ high purity beam.Considering the requirement of the target ion species、the running energy range of JUNA accelerator(70 ~ 800 keV)and the low background operating conditions,the LEBT adopts double solenoid structural design to achieve the beam matching to back-end the acceleration tube,meanwhile we set an analyzing dipole with 30 degree deflection angle and double focusing structure between the solenoids to achieve the exchange of different particles and removel of the impurity particles.Through the beam dynamics simulation,we optimize the beam transmission element,evaluate the loss position of the beam and set the beam dump,which can meet the the transmission of high purity and strong dynamic beam that JUNA requires.The preliminary debugging results show that it can meet the beam requirement of the project.Impurity ions(H2~+,H3~+)pollution problem has been the difficulty of a high current proton accelerator,for this reason the CIADS injector is considered for a design with a quality analysis system.For this scenario,we use JUNA’s LEBT for a feasibility study.By comparing the simulation result to the experimenting result of the beam quality of 35 keV、10 mA proton beam which CIADS injector II requires after the analyzing dipole,we find that the infuence of the high-order magnetic fields of the dipole magnet decreases the proton beam quality,and the effect increases with the increase of the beam envelope.This result will provide a more specific design reference for CIADS injector’s LEBT design.The key to the high current ion source is the establishment of high density plasma.For obtaining a high density plasma in ECR ion sources,we investigated a new microwave model with no cutoff density-Electronic Bernstein Wave(EBW).Based on systematically investigation and analysis,according to the feasibility of establishing EBW mode under with 14.5 GHz microwave,we set up the rational research platform and carry out a preliminary experimental exploration,then we discuss and analyze the existing problems of the experiment.