本文選題：帶電顆粒Mie理論 + 散射相位函數(shù)　； 參考：《蘭州大學(xué)》2017年碩士論文

【摘要】：快速發(fā)展的電磁波技術(shù)在很多領(lǐng)域得到廣泛的應(yīng)用,例如極端環(huán)境(沙塵暴、霧霾等天氣)中電磁波的傳輸以及利用電磁波技術(shù)對大氣中顆粒成分的監(jiān)測等。顆粒的屬性如顆粒帶電會對電磁波散射產(chǎn)生影響,直接影響其信號傳輸質(zhì)量以及監(jiān)測結(jié)果。因此,本碩士論文基于帶電顆粒電磁波的散射性質(zhì),對帶電顆粒電磁波散射相位函數(shù)、帶電顆粒屬性包括帶電量和相對折射率以及帶電顆粒系統(tǒng)中雷達(dá)大氣探測能力展開研究,主要工作如下:基于帶電顆粒的Mie散射原理,首先,推導(dǎo)了球形帶電顆粒的散射相位函數(shù),得到帶電顆粒的散射相位函數(shù)與不帶電顆粒的散射相位函數(shù)之間存在顯著差異,主要體現(xiàn)在散射相位函數(shù)隨著顆粒表面電導(dǎo)率、顆粒尺度參數(shù)、電磁波入射頻率以及顆粒相對折射率的變化而發(fā)生改變,顆粒帶電后會增加后向散射相位函數(shù)的值,對固定入射波頻率和顆粒相對折射率的情形下,散射相位函數(shù)隨顆粒表面電導(dǎo)率的變化在每一種顆粒尺度參數(shù)下都存在一個(gè)臨界表面電導(dǎo)率,如果顆粒表面電導(dǎo)率大于此臨界值,散射相位函數(shù)對顆粒表面電導(dǎo)率的依賴性將會減弱,表明顆粒表面帶電起到了主導(dǎo)作用;其次,導(dǎo)出了在橫向分量方向上電磁波散射電場的振幅比及相位差,分析發(fā)現(xiàn)在垂直于入射波的方向上散射電場振幅比和相位差與顆粒表面帶電量的大小之間存在非常好的線性相關(guān)關(guān)系,此線性相關(guān)關(guān)系會隨著不同的影響參數(shù)而表現(xiàn)在線性相關(guān)的斜率不同,根據(jù)此關(guān)系提出了基于電磁波散射信號反演顆粒帶電量和顆粒相對折射率的方法;最后,分析了帶電顆粒系統(tǒng)的消光系數(shù)和后向散射系數(shù),導(dǎo)出雷達(dá)照射在顆粒系統(tǒng)上的雷達(dá)比率,通過對雷達(dá)比率的分析,發(fā)現(xiàn)不同波段雷達(dá)對探測帶電顆粒系統(tǒng)的能力之間存在著顯著的差異,特別地對沙塵顆粒系統(tǒng),沙粒帶電對激光波段雷達(dá)探測的影響最小,相比較于其他波段雷達(dá),激光波段雷達(dá)在探測帶電沙粒系統(tǒng)具有明顯的優(yōu)勢,另外,雷達(dá)探測能力的大小也會隨著顆粒表面帶電量大小及顆粒屬性的變化而出現(xiàn)變化。
[Abstract]:The rapid development of electromagnetic wave technology has been widely used in many fields, such as the transmission of electromagnetic wave in extreme environment (dust storm, haze and so on) and the monitoring of particle composition in atmosphere by electromagnetic wave technology. The properties of particles, such as charged particles, will have an effect on electromagnetic wave scattering, which will directly affect the signal transmission quality and monitoring results. Therefore, based on the scattering property of charged particle electromagnetic wave, the phase function of charged particle electromagnetic wave scattering, the properties of charged particle, including the band electric quantity and relative refractive index, and the radar atmospheric detection ability in charged particle system are studied in this thesis. The main work is as follows: based on the Mie scattering principle of charged particles, first of all, the scattering phase function of spherical charged particles is derived, and the difference between the scattering phase functions of charged particles and that of uncharged particles is obtained. The scattering phase function changes with the changes of surface conductivity, particle size parameters, incident frequency of electromagnetic wave and relative refractive index of particles, and increases the value of backscattering phase function after charged particles. For the case of fixed incident wave frequency and relative refractive index of particles, the variation of scattering phase function with particle surface conductivity has a critical surface conductivity under each particle size parameter. If the surface conductivity of particles is larger than this critical value, the dependence of scattering phase function on the surface conductivity of particles will be weakened, indicating that charged particles play a leading role. Secondly, The amplitude ratio and phase difference of electromagnetic wave scattering electric field in the direction of transverse component are derived. It is found that there is a good linear correlation between the amplitude ratio and phase difference of scattering electric field perpendicular to the incident wave and the amount of electrical energy on the surface of the particle. According to the linear correlation relationship, the slope of linear correlation is different with different influence parameters. Based on this relationship, a method for retrieving the energy of particle band and the relative refractive index of particles based on electromagnetic wave scattering signal is proposed. The extinction coefficient and backscattering coefficient of charged particle system are analyzed, and the radar ratio of radar irradiating on particle system is derived. It is found that there is a significant difference in the ability of different band radar to detect charged particle system, especially for dust particle system, the influence of charged sand particle on lidar detection is the least, compared with other band radar. Lidar has obvious advantages in detecting charged sand particle system. In addition, the detection ability of lidar will change with the change of the electric quantity of particle surface and the properties of particle.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O441.4

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