Research On Transmission Characteristics Of Electromagnetic Wave In Charged Particle Stream

In the low ionosphere,especially in the D layer,the propagation of radio waves may not only be affected by electrons,but also by ions.However,due to the large mass of ions and the slow speed,generally only the interaction between electromagnetic waves and electrons is considered when calculating the permittivity,and the contribution of the ion collision term is ignored.In this master dissertation,in order to explore the influence of ions on the permittivity and conductivity,we have carried out numerical simulation and experimental research.The research work of this master dissertation includes:The effects of ions on the permittivity and conductivity of plasma are discussed through numerical calculations.The calculation results show that: in some special cases of the ionosphere(such as the occurrence of bite-out condition),the ion collision term has a significant impact on the calculation results when calculating the permittivity and conductivity of the plasma.This master dissertation introduces the transmission matrix method,and realizes the electromagnetic wave transmission calculation model in the charged particle stream through programming.After selecting the appropriate simulation parameters,the influence of plasma density,molecular number density,and incident angle on the transmission characteristics of electromagnetic waves is obtained.In order to further understand the influence of ions on the permittivity and conductivity of plasma,this master dissertation designs a set of experimental platform for electromagnetic wave transmission in a charged particle stream.In the experiment,a radar radio frequency operating at 35 GHz is used.The ratio frequency transceiver system is used as the signal transmitting and receiving source,the Ka-band horn antenna is used as the transmitting antenna and the receiving antenna,and the high-vacuum cavity and two ionization sources(Kaufman ion source and hollow cathode electron source)are used as the experimental platform.This master dissertation has completed the equivalent measurement experiment based on the radar radio frequency transceiver system.In the case of several different media,the electromagnetic wave signal received by the receiving antenna is collected through the mid-amp monitoring.The experimental results show that:as the borosilicate glass medium increases,the signal amplitude has been significantly attenuated,and there is also a certain phase shift.At the same time,it is found that the borosilicate glass medium attenuates electromagnetic waves more significantly than the air medium.This master dissertation also completed the construction of an experimental platform for electromagnetic wave transmission in a charged particle stream,in which the electron source and ion source can simulate the bite-out condition and other environments,and further verify the results of the theoretical analysis.The system can also test the ionization source flow rate,the influence of vacuum and power on the attenuation of electromagnetic waves.