Interactions Of Electromagnetic Waves With Some Environmental Plasmas

The interaction of electromagnetic waves with environment plasma is one of the most fundamental problems in electromagnetic field theory and plasma physics,which is a cross-disciplinary application of electrical engineering and plasma physics.It directly affects the national economics,technology advance and people's daily life.This thesis is supported by the Space Environment Simulation Research Infrastructure(SESRI),a scientific project for a major national facility of fundamental researches,which has recently been launched at Harbin Institute of Technology(HIT).Based on the scientific demands of SESRI,this thesis investigates the interaction of electromagnetic waves with two typical environment plasmas: the blackout plasma with high electron density and strong collision frequency,and the magnetosphere plasma with low electron density and weak even none collision frequency.The interactions of RF electromagnetic waves with blackout plasma environment are the essential physics problems in solving the blackout issue encountered by hypersonic vehicles,and the excitation and propagation of electromagnetic waves in the terrestrial magnetosphere are relevant to the security of artificial spacecrafts.Therefore,electromagnetic waves in environmental plasma are related to the national security and people's lives.In order to study the communication blackout problem encountered by hypersonic vehicles in the near space,we summarize the published data from flight and ground experiments as well as simulations to abstract the main features of blackout plasma sheathes with a series of hypotheses.Further,we model the blackout plasma with twofluid theory.Finally,we build up the finite element modeling of interactions between small electrical dipole antenna and blackout plasma sheathes.Based on the numerical model,considering the parameters used in ground experiments,we simulate the interactions between small electrical dipole antenna and blackout plasma sheathes.The results are consistent with experiments,which validate the numerical modeling.Through analyzing the numerical results,we proposes the physics picture of interactions between small electrical dipole antenna and blackout plasma sheathes,and then a matching approach based on it.The numerical results show that this novel method can improve the flight antenna matching and increase the radiation capability,so that it can mitigate blackout problems under some conditions.The numerical solutions of linear dispersion relation and fully kinetic equations are hard to obtain,because the frequency and wave number of ion Bernstein waves in the terrestrial magnetosphere span over wide ranges.In order to overcome this issue,we propose a Gyro-kinetic electron and Fully kinetic Ion(Ge Fi)method to simulate.Through comparison among the results obtained from linear dispersion relation solver,fully kinetic simulations and Ge Fi simulations,the capability of Ge Fi method in simulating ion Bernstein waves in the terrestrial magnetosphere is verified.By increasing the mass and speed ratios,the prediction made by linear theory is also confirmed by Ge Fi studies.Taking advantage of Ge Fi in high mass and speed ratios,Ge Fi simulations reveal the nonlinear wave-wave interactions at the saturation stage,which is absent in previous linear theory or fully kinetic simulations results.Finally,we propose an automatic method using linear perturbed kinetic simulation to study the linear growth rate of the ion Bernstein instabilities.This method avoids manually adjusting initial value of the linear dispersion relation solver,so it makes lives easier.Then,we have verified this method through comparing the linear growth rate obtain through both methods.Finally,we use the new method to explore the dependency of linear growth rate on the hot proton distribution.