Study On Electromagnetic Characteristics Of Composite Structure With Plasma And FSS Period Matching

In the design of artificial electromagnetic structures,a structure in which the arrangement order of the medium is periodically arranged according to a certain rule is generally referred to as a periodic electromagnetic structure.This kind of structure has very important research significance in the field of microwave because of its special electromagnetic characteristics.For the study of periodic electromagnetic structure,frequency selective surface(FSS)and plasma photonic crystal(PPC)are representative,and have broad application prospects in fields such as scattering suppression.At present,by using the FSS to suppress the electromagnetic echo energy,the Salisbury screen technology mainly uses the principle of the double-layer structure to reflect the phase mismatch and cancellation of the echo,which has become an important method for scattering suppression feature at present.Among the bottlenecks currently to be resolved by this technology,how to widen the effective frequency band and how to increase the effective incident angle range are two important research directions,that is,the pursuit of wideband and angle has nothing to do with it.In order to address the above problems,the main research methods at home and abroad have been to adopt multi-layered frequency-selective structures and the characteristics of modulated interlayer media.The technical route of matching modulation by introducing plasma has not been publicly reported.This paper focuses on the structure and resonance characteristics of plasma and frequency-selective surface coupling and modulation methods to carry out research and exploration of this new technological route.The main innovative research works include:(1)Aiming at the problem of coupling design of metal periodic structure and plasma periodic structure,an artificial electromagnetic structure with a composite of plasma and FSS is proposed.This structure combines a linear array of square metal units in the FSS with a plasma columnar unit through periodic matching.This composite structure not only has the ability of plasma to modulate electromagnetic wave dynamics,but also can tune the resonance frequency of both to enhance the attenuation characteristics of electromagnetic waves and widen the suppression frequency band of electromagnetic wave scattering characteristics.(2)Aiming at the problem of the complexity of the metal periodic structure in the coupling design optimization,a modular pixel metal unit design method was introduced to achieve a multi-objective optimization effect with better broadband characteristics and angular characteristics.Through the combination of experiments and simulations,it is verified that the composite structure has wider suppression frequency band and stronger attenuation characteristics and better angular stability than the unmatched state for electromagnetic waves.Based on this,combined with the actual engineering application requirements,the feasibility of reducing the working voltage of plasma by introducing nanostructures was discussed.First,several typical one-dimensional nanowire structures were prepared using the KQX system,and their morphological features were highly abstracted and refined to calculate the electric field distribution of different nanostructure discharges.Combined with the Townsend model,the influence of different electric field distributions on the impact ionization Townsend coefficient is calculated.Finally,the breakdown voltages of the two nanostructured electrodes under low pressure and normal pressure conditions were calculated by theoretical models.It is theoretically proved that the introduction of nanostructures can indeed reduce the plasma operating voltage.The results obtained have guidance and significance for widening the electromagnetic wave scattering suppression frequency band of FSS through the periodic structure of plasma under the condition of safe operating voltage.