發(fā)布時(shí)間：2018-05-31 06:11

  本文選題：塵埃等離子體 + 電磁波傳輸��； 參考：《哈爾濱工業(yè)大學(xué)》2017年博士論文

【摘要】：在宇宙空間中,物質(zhì)大多以等離子體狀態(tài)存在。由于人類的生產(chǎn)及生活,每天都會(huì)產(chǎn)生超過40公噸的塵埃進(jìn)入地球大氣層,因此在地球軌道空間中形成一種等離子體與塵埃共存的狀態(tài)——塵埃等離子體。其改變了近地空間的電磁環(huán)境,對空間通信系統(tǒng)產(chǎn)生不可預(yù)估的影響,如極區(qū)中層夏季回波、夜光云等現(xiàn)象。同時(shí)塵埃等離子體在再入飛行器通信、火箭噴焰的微波衰減以及工業(yè)制造業(yè)等科學(xué)及工業(yè)領(lǐng)域的重大問題中也具有重要的應(yīng)用價(jià)值。近幾年塵埃等離子體中電磁波的傳輸問題成為科學(xué)領(lǐng)域研究的熱點(diǎn),主要是由于電磁波傳輸問題與等離子體診斷、空間探測、再入物理以及無線電通信等領(lǐng)域都密切相關(guān)。對于電磁波與塵埃等離子體相互作用的研究主要集中在塵埃聲波、塵埃孤波、塵埃離子聲波等方面,對塵埃等離子體中電磁波傳輸特性方面缺少準(zhǔn)確、系統(tǒng)的理論研究,而實(shí)驗(yàn)研究更鮮有報(bào)道。因此本文從理論分析、數(shù)值模擬、實(shí)驗(yàn)驗(yàn)證角度入手,系統(tǒng)性研究電磁波在塵埃等離子體中的傳輸特性。本文以塵埃顆粒與等離子體復(fù)雜相互作用理論為出發(fā)點(diǎn),結(jié)合統(tǒng)計(jì)物理學(xué)動(dòng)理論方法,分別推導(dǎo)出弱碰撞完全電離和弱電離塵埃等離子體的介電常數(shù)表達(dá)式。弱碰撞完全電離塵埃等離子體是一個(gè)新提出的模型,由于沒有中性分子的存在,電子與離子間的碰撞直接決定了電磁波的傳輸特性,而在弱電離塵埃等離子體中,存在大量未電離的中性氣體分子,電子與中性分子的碰撞決定了電磁波的傳輸特性。分別建立電磁波在弱碰撞完全電離和弱電離塵埃等離子體中的傳輸模型,利用矩陣光學(xué)法進(jìn)行數(shù)值模擬,得到電磁波的反射、透射和吸收系數(shù)與塵埃顆粒帶電量、尺寸、密度以及塵埃等離子體厚度等參數(shù)的關(guān)系。對比電離度不同的兩種塵埃等離子體對電磁波傳輸?shù)牟煌绊?說明碰撞頻率是影響電磁波在塵埃等離子體中傳輸?shù)闹饕蛩�。采用�?shí)驗(yàn)室空心陰極放電等離子體產(chǎn)生裝置,利用篩網(wǎng)振動(dòng)裝置實(shí)現(xiàn)低氣壓塵埃顆粒注入,形成較為穩(wěn)定的塵埃等離子體環(huán)境。利用多物理場耦合分析軟件COMSOL Multiphysics模擬產(chǎn)生塵埃等離子體環(huán)境,分析所產(chǎn)生的塵埃等離子體的相關(guān)特性,得到空心陰極放電塵埃等離子體特征參數(shù)的時(shí)空分布。同時(shí)利用朗繆爾探針對塵埃等離子體的參數(shù)進(jìn)行診斷測量,探測塵埃顆粒注入前后電子密度、電子溫度的變化,得到的測量結(jié)果與模擬結(jié)果相吻合,塵埃顆粒與電子、離子不斷碰撞而被充電從而帶上負(fù)電荷,電子密度降低。利用矢量網(wǎng)絡(luò)分析儀配合相應(yīng)的微波喇叭天線,對塵埃等離子體中電磁波傳輸特性進(jìn)行實(shí)驗(yàn)研究,并與數(shù)值模擬結(jié)果進(jìn)行對比。通過改變塵埃顆粒的密度以及放電腔內(nèi)的電離氣體成分、壓強(qiáng)、放電功率等因素,測量不同情況下塵埃等離子體的電磁波參數(shù),分析確定塵埃等離子體中影響電磁波傳輸特性的基本參數(shù),從而得到塵埃等離子體中電磁波的傳輸規(guī)律。結(jié)果表明,帶電塵埃顆粒的物理特性以及塵埃等離子體的放電環(huán)境都對電磁波的傳輸產(chǎn)生影響。通過本課題的研究可以發(fā)現(xiàn),塵埃等離子體中塵埃顆粒對電磁波傳輸?shù)挠绊懖荒芎雎?同時(shí)對于降低火箭噴焰對微波衰減、減弱飛行器再入“黑障”效應(yīng)、解決極區(qū)夏季回波現(xiàn)象等科學(xué)及工程問題提供實(shí)驗(yàn)基礎(chǔ)和理論指導(dǎo)。
[Abstract]:In cosmic space, most of the matter exists in the state of plasma. Because of human production and life, more than 40 metric tons of dust will be produced every day into the earth's atmosphere, so a state of coexistence of plasma and dust in the earth's orbit space, such as dust, has changed the electromagnetic environment of the near earth space. The spatial communication system has an inpredictable effect, such as the phenomenon of the summer echo in the polar region and the Noctiluca cloud. At the same time, the dust plasma is also of important application value in the reentry vehicle communication, the microwave attenuation of the rocket flame and the major problems in the industrial manufacturing industry. The problem of wave transmission has become a hot topic in the field of science, mainly due to the close correlation between electromagnetic wave transmission and plasma diagnosis, space detection, reentry physics and radio communication. The research on the interaction of electromagnetic wave with dust plasma is mainly in the dust wave, dust solitary wave, and dust ion sound wave On the other hand, the transmission characteristics of electromagnetic waves in the dust plasma are lack of accurate, systematic theoretical research, and the experimental research is more rarely reported. Therefore, this paper systematically studies the transmission characteristics of electromagnetic waves in the dust plasma from the theoretical analysis, numerical simulation and experimental verification. This paper is based on the complexity of dust particles and plasma. The theory of interaction is the starting point and the dielectric constant expression of the weakly collisional fully ionized and weakly ionized dust plasma is derived by the method of statistical physics dynamic theory. The weak collision completely ionized dust plasma is a new model. Because there is no neutral fraction, the collision between electrons and ions is directly determined. A large number of unionized neutral gas molecules exist in the weak electricity from the dust plasma. The collisions between the electrons and the neutral molecules determine the transmission characteristics of the electromagnetic waves. The propagation model of the electromagnetic wave in the weak collision completely ionized and weakly ionized dust plasma is established, and the numerical value of the electromagnetic wave is established by matrix optics. The relation between the reflection, the transmission and absorption coefficient of the electromagnetic wave and the parameters of the charged particle size, size, density and the thickness of the dust plasma is obtained. The effects of the two kinds of dust plasma on the transmission of electromagnetic wave are compared. It is shown that the collision frequency is the main influence of the electromagnetic wave propagation in the dust plasma. Factors. Using a laboratory hollow cathode discharge plasma generating device, the low pressure dust particles are injected by the screen vibrating device to form a stable dust plasma environment. The dusty plasma environment is simulated by the multi physical field coupling analysis software COMSOL Multiphysics, and the dust plasma produced is analyzed. The spatial and temporal distribution of the characteristic parameters of the dust plasma of the hollow cathode discharge is obtained. At the same time, the parameters of the dust plasma are diagnosed and measured by the Langmuir probe, and the electron density and the change of the electron temperature are detected before and after the dust particles are injected. The results of the measurement are consistent with the simulation results, and the dust particles and the electrons are separated from the dust particles. By using the vector network analyzer and the corresponding microwave horn antenna, the transmission characteristics of the electromagnetic wave in the dust plasma are experimentally studied and compared with the numerical simulation results. By changing the density of the dust particles and the ionized gas in the discharge cavity, The parameters of the electromagnetic wave in the dust plasma are measured in different conditions, and the basic parameters affecting the transmission characteristics of the electromagnetic wave in the dust plasma are determined, and the transmission law of the electromagnetic wave in the dust plasma is obtained. The results show that the physical properties of the dust particles and the dust plasma are shown. The discharge environment affects the transmission of electromagnetic wave. Through this research, we can find that the influence of dust particles on the transmission of electromagnetic wave can not be ignored. At the same time, it can reduce the microwave attenuation, weaken the "black barrier" effect of the reentry of the aircraft and solve the scientific and engineering problems of the summer echo phenomenon in the polar region. Provide experimental basis and theoretical guidance.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O53;O441.4

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1 賈潔姝;電磁波在塵埃等離子體中的傳輸特性研究[D];哈爾濱工業(yè)大學(xué);2017年

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本文編號(hào)：1958599