Back-streaming electrons gain significant energy due to the high voltage of the extraction system for a high-current ion source.By theoretical calculation,the particle flux accounts for 13.88% of the total beam curren...Back-streaming electrons gain significant energy due to the high voltage of the extraction system for a high-current ion source.By theoretical calculation,the particle flux accounts for 13.88% of the total beam current,and the power flux accounts for about 7.5% of the total beam power.This shows that back-streaming electrons are very destructive to the plate of electron absorption that is installed opposite of the accelerator.At the same time,as particles impinge on grids,the energy level that the grids absorb will be really high.Compared with the water flow calorimetry data of ion sources on the ASIPP-NBI testbed,it can be found that,as the high voltage of the extraction system rises,the particle flux and the power flux of the back-streaming electrons are essentially in the same proportions.Therefore,the corresponding energy deposited on the components of the ion source will grow by the same percentage with the increase in high voltage,which demonstrates strong inhibition to improving the neutral beam power injected into a tokamak.展开更多
The back-streaming neutrons from the spallation target at CSNS are very intense, and can pose serious damage problems for the devices in the accelerator-target interface region. To tackle the problems, a possible sche...The back-streaming neutrons from the spallation target at CSNS are very intense, and can pose serious damage problems for the devices in the accelerator-target interface region. To tackle the problems, a possible scheme for this region was studied, namely a specially designed optics for the proton beam line produces two beam waists, and two collimators are placed at the two waist positions to maximize the collimation effect of the back-streaming neutrons. Detailed Monte Carlo simulations with the beams in the two different CSNS phases show the effectiveness of the collimation system, and the radiation dose rate decreases largely in the interface section. This can ensure the use of epoxy coils for the last magnets and other devices in the beam transport line with reasonable lifetimes, e.g., thirty years. The design philosophy for such an accelerator-target interface region can also be applicable to other high-power proton beam applications.展开更多
基金supported by National Natural Science Foundation of China(No.11405207,No.11505225 and No.11675215)partly supported by the International Science and Technology Cooperation Program of China(No. 2014DFG61950)the Sciences foundation of ASIPP(No. DSJJ-15-GC03)
文摘Back-streaming electrons gain significant energy due to the high voltage of the extraction system for a high-current ion source.By theoretical calculation,the particle flux accounts for 13.88% of the total beam current,and the power flux accounts for about 7.5% of the total beam power.This shows that back-streaming electrons are very destructive to the plate of electron absorption that is installed opposite of the accelerator.At the same time,as particles impinge on grids,the energy level that the grids absorb will be really high.Compared with the water flow calorimetry data of ion sources on the ASIPP-NBI testbed,it can be found that,as the high voltage of the extraction system rises,the particle flux and the power flux of the back-streaming electrons are essentially in the same proportions.Therefore,the corresponding energy deposited on the components of the ion source will grow by the same percentage with the increase in high voltage,which demonstrates strong inhibition to improving the neutral beam power injected into a tokamak.
基金Supported by National Natural Science Foundation of China(11235012,10975150)
文摘The back-streaming neutrons from the spallation target at CSNS are very intense, and can pose serious damage problems for the devices in the accelerator-target interface region. To tackle the problems, a possible scheme for this region was studied, namely a specially designed optics for the proton beam line produces two beam waists, and two collimators are placed at the two waist positions to maximize the collimation effect of the back-streaming neutrons. Detailed Monte Carlo simulations with the beams in the two different CSNS phases show the effectiveness of the collimation system, and the radiation dose rate decreases largely in the interface section. This can ensure the use of epoxy coils for the last magnets and other devices in the beam transport line with reasonable lifetimes, e.g., thirty years. The design philosophy for such an accelerator-target interface region can also be applicable to other high-power proton beam applications.
