Study On Electron Beam Transmission And Characteristics In Different Environments

As an important branch of plasma physics,electron beam transmission is of great significance to study its transmission characteristics in different environments for the detection of magnetic fields and the development of high-power resources.When the electron beam is transmitted in the real scene,it is often necessary to consider the influence of the external environment.For example,the transmission in the gas will ionize and generate secondary electrons and cations to form the ion focus area to pinch the radius of the electron beam.In order to realize the stable,continuous and efficient transmission of electron beams in the actual environment,it is necessary to analyze the transmission characteristics of electron beams in various environments.This paper starts from the three environments of electron beams in vacuum,gas,and background plasma,and focuses on analyzing the difference in radius of electron beams caused by different approximation treatments when electron beams are transmitted in vacuum;when electron beams are transmitted in gas The degree of agreement between theory and simulation;the effect of gas pressure changes on electron beam transmission and the effect of background plasma on electron beam transmission quality.Based on this,the parameters of electron beam transmission in different environments are analyzed,which provides a theoretical basis for the application of high-quality electron beam transmission.The main work and research contents of this paper are as follows:(1)Different approximation methods are used in the simulation analysis of the electron beam to cause differences in the electric field and magnetic field of the sheet beam and the columnar beam,which affects the size of the space charge effect during the electron beam transmission,resulting in the dispersion radius of the electron beam different.Considering that most of the particle clusters produced in the experiment are cylindrical electron beams,the development trend of electron beam dispersion radius in vacuum environment is compared with the electron beam simulated by cylindrical coordinates as a reference.On this basis,a transmission model of the electron beam in the gas is established,and the comparison of the fit between the simulated envelope radius and the envelope radius equation is realized.Then,the influence of contrast gas pressure changes on electron beam transmission was analyzed。Considering that the open space will interfere with the full electromagnetic model of the electron beam,this paper uses the traditional particle simulation electrostatic model,and adds the influence of the radial magnetic field of the electron beam itself on the envelope of the electron beam to construct the electron beam in the cylindrical coordinate system.simulation calculation.When the electron beam is transmitted in the gas,it is considered that the electron beam will have ionization collision,elastic collision,electron avalanche and other physical processes with the local gas.In order to save computing resources,Monte Carlo technology is used to calculate and simulate the electron beam when the electron beam is transmitted in the gas.The process of colliding with the gas realizes the combination of theory and simulation when the electron beam is transported in the gas.At the same time,it was found that in the process of increasing the gas pressure,due to the gradual increase of secondary electrons and cations generated,it is easy to form an ion focus area,which promotes the electron beam to travel farther under the Budker pinch condition.(2)Compared with the electron beam transmitted in vacuum or gas,the background plasma with different density distribution can make the electron beam flow suffer from a better balance between the pinch force and the divergence force during the transmission process,so as to realize the effective transmission of electron beam current in different application occasions.Based on the laboratory realization and preparation purposes,the electron beam transmission characteristics in background plasma with different density distributions are calculated and analyzed,and the background plasma distribution that can optimize the electron beam transmission quality and the background plasma distribution that seriously destroys the electron beam transmission quality are given.(3)By comparing the plasma distribution generated in the laboratory and the theoretical model of the normal plasma distribution,a plasma Gauss distribution that is similar to the plasma density distribution generated in the laboratory is proposed,which will provide a basis for future experiments Provide theoretical reference.The transport quality of electron beam in plasma Gauss distribution and plasma uniform distribution was analyzed,and the influence of electron beam density to background plasma density on electron beam radius,electron beam oscillation frequency and electron beam oscillation amplitude was revealed.The results show that the electron beam transported in the plasma Gauss distribution has advantages in all aspects of beam quality compared with the electron beam transported in the uniform plasma.