Influence On Transmission Characteristics Of 10GHz Electromagnetic Wave With Femtosecond Laser-produced Plasma Filaments Array

The interaction of electromagnetic wave with femtosecond laser-produced plasma filaments array is a research hotspot in the field of laser technology.However,the research on the "fence" array composed of femtosecond laser-produced plasma filaments to interfere with EM wave transmission is rare.In this dissertation,based on the three characteristics of reflection,transmission and absorption,the influence on the transmission characteristics of 10GHz EM wave with femtosecond laser-produced plasma filaments array are studied with focusing on the effects of plasma array parameters,plasma characteristic parameters and array layer number.The calculation results show that the plasma filaments array becomes transparent when the direction of the EM wave electric field is perpendicular to the filaments axis,regardless the incidence angle of the microwave with respect to the filaments.At the same time,the influence of the same size perfect electric conductor array on the reflection and transmission coefficients as a function of different frequencies of EM waves is also analyzed.Increasing the filaments diameter or electron number density,or decreasing the filaments spacing or electron temperature will lead to the reflection increasing and the transmission decreasing.The maximum reflection coefficient of 10GHz microwave with plasma filaments array is up to 0.88 while the filaments diameter is 500 jpm,the filaments spacing is 1 mm,and at this time the electron number density is ne = 1×1O23m-3 and the electron temperature is 0.3 eV.When the number of filaments array layers is increased,the transmittance decreases,eventually approaches zero,and the reflectance remains constant.It is first proposed that the femtosecond laser-produced plasma filament array can be applied to plasma stealth.Results show that the echo loss can reach to-14.2 dB when put an oblique filament array before a target,and verified the feasible of filament array for plasma stealth.According to the model and calculation results of this dissertation,the femtosecond laser-produced plasma filaments array can be applied to the electronic countermeasure technologies such as the target stealth and the false target,if the plasma characteristic parameters and filaments array parameters are reasonably adjusted.