Research On Micro-scale Radiation Characteristics Of High Porosity Metal Material

Microscale radiation effect such as photon tunneling effect,surface plasmon polaritons,magnetic polaritons,microcavity resonance effect,phontonic band-gap effect and so on can be excited by micro-structure,which is applied for tailoring thermal radiation properties.The properties of microscale radiation has important application in solar engineering,photoelectric conversion,infrared detection and energy harvesting.So far microscale radiation has received intensive investigation.The microscale radiation research on surface micro-structure has been studied a lot while the reports on spatial micro-structure are few.High porosity metal material is a kind of material with spatial and surface micro-structure.It also involving spectral selective absorption and multiple scattering.The current work mainly applied finite difference time domain method(FDTD)to investigate the microscale radiation characteristics of high porosity metal material on the purpose of modifying the spectral radiative properties.Based on electromagnetic scattering thoery,the microscale radiation characteristic of silver cubic element cell is investigated.Electromagnetic field and poynting vector distribution are analysised.The absorption cross-crossection peak arises when electric field and poynting vector have strong interaction with ribs.Further more,the attentuation characteristic is disscussed for different microstructure based on silver cubic element cell.The attentuation of cavity is strongest.Microscale radiation properties of mutiple cubic layers are investigated in visible light band.Convergence test method is proposed in order to get more accuracy results.The absorption relation of cubic element cell,single layer cubic sturcture and infinite plate is presented.Radiative properties is changed by single layer cubic structure,and it is not linear combination of cubic element cell.Influence of porosity and oblique incidence on absorptivity of single layer cubic structrue is studied.The absorptivity shows different regions with porosity changing whicn can be divided into strong,middle and weak portion.Incident angle has influence on the radiative property of single layer cubic structrue,but the rules is not obvious.Radiation characteristic of mutiple layers cubic structrure is explored.Result shows that the absorptivity is enhanced at wavelength 0.457?m.Three layers cubic structrue can stop the light from going through at wavelength of 0.35~0.55?m which can be used as filter material.Spherical hollow aluminum element cell model is designed and its attentuation characteristic is investigated.The result shows that absorption behavior presented to be very weak,but scattering behavior shows to be quite strong in wavelength range of 1~15?m.Using Durde model and n,k model,the absorption characteristic of single layer spherical hollow structure is considered,respectively.For the two models,change rules of radiative property is consistent,but the peak value is a little difference.Influence of nonmetal material SiO2,Si and graphene is also considered.The absorption is enhanced at wavelength of 1~6?m for Si substrate single layer spherical hollow structure.