發(fā)布時間：2018-03-14 11:14

  本文選題：二元復(fù)雜等離子體　切入點(diǎn)：微重力　出處：《東華大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：復(fù)雜等離子體實(shí)驗(yàn)作為一門新興的研究課題正吸引著研究學(xué)者們越來越多的關(guān)注。隨著復(fù)雜等離子體系統(tǒng)中各種物理現(xiàn)象及結(jié)構(gòu)的發(fā)現(xiàn),作為一個可以從原子層面模擬物理性質(zhì)的媒介,其獨(dú)特的優(yōu)勢逐漸突顯。復(fù)雜等離子體實(shí)驗(yàn)由最初的地面實(shí)驗(yàn)發(fā)展到微重力條件下的實(shí)驗(yàn),從單元系統(tǒng)發(fā)展到二元以及多元系統(tǒng),經(jīng)歷了卓越的成長。較為經(jīng)典的國際空間站實(shí)驗(yàn)裝置PK-3 Plus服役多年,研究成果豐富。復(fù)雜等離子體系統(tǒng)在研究晶格、密度波、分相等相關(guān)動力學(xué)過程中,給學(xué)者們提供了獨(dú)特的視角以及不一樣的發(fā)現(xiàn)。實(shí)驗(yàn)中發(fā)現(xiàn)了波傳遞的現(xiàn)象,且這些波是自激產(chǎn)生的,由此引發(fā)了人們對復(fù)雜等離子體自激密度波的實(shí)驗(yàn)探索。在一定的實(shí)驗(yàn)條件下,自由能的存在是激發(fā)密度波的前提條件。一元復(fù)雜等離子體系統(tǒng)中波的傳播會出現(xiàn)波紋的斷裂、分叉等現(xiàn)象,這些現(xiàn)象的微觀研究對許多宏觀現(xiàn)象的解釋有著重要作用。二元復(fù)雜等離子體系統(tǒng)由于不同大小顆粒在系統(tǒng)中的受力不同而出現(xiàn)自主分相的過程,較小的顆粒會占據(jù)塵埃粒子云的內(nèi)圈空間,較大顆粒與較小顆粒分相并占據(jù)塵埃云的外部空間。分據(jù)不同區(qū)域的兩種顆粒之間存在著一圈較為明顯的分界面。復(fù)雜等離子體系統(tǒng)中的密度波由于其所在的傳播介質(zhì)即塵埃顆粒的不同而具有不同的傳播頻率,因此二元系統(tǒng)中的波在小顆粒所在的內(nèi)圈以及大顆粒所在的外圈具有不同的傳播頻率。密度波的傳播方向由塵埃云中間的空洞向周圍呈球面狀傳播,當(dāng)以小顆粒為傳播介質(zhì)的波以一定的頻率向外傳播至界面時,分界面前后不同大小的顆粒相互碰撞,導(dǎo)致密度波以后者即波在大顆粒中傳播的頻率反射回小顆粒所在的內(nèi)圈區(qū)域。又由于整個系統(tǒng)的耗散性,以小顆粒為介質(zhì)的波在傳播到大顆粒的區(qū)域后漸漸耗散消失。為了驗(yàn)證反射波的存在,我們辨別顆粒,做出了顆粒動能周期圖,從中我們可以清楚的看到顆粒動能的反向變化趨勢。另一方面為了了解介質(zhì)即塵埃顆粒在波傳播中的運(yùn)動學(xué)過程我們進(jìn)行了顆粒的追蹤,追蹤發(fā)現(xiàn)一個波前傳播周期內(nèi),大顆粒振動一個周期,而小顆粒卻表現(xiàn)出兩個不同振幅,不同頻率的周期。顆粒的振動形式受到波的影響,當(dāng)單一形式的波傳播到介質(zhì)時,介質(zhì)以該波的頻率以及傳遞到它的能量大小(振幅)振動;當(dāng)同時有兩種形式的波當(dāng)波的一種形式(實(shí)驗(yàn)中以正方向傳播的入射波)傳播到介質(zhì)時,介質(zhì)以該波的頻率及能量大小(振幅)來振動,而后當(dāng)另一種波(實(shí)驗(yàn)中的反射波)傳播到該介質(zhì)時,反射波與入射波耦合,介質(zhì)同時表現(xiàn)出這兩種振動的特征。整個過程很好的說明了分界面上密度波傳播的特點(diǎn)以及波在傳播的過程中介質(zhì)的作用。
[Abstract]:As a new research subject, complex plasma experiment is attracting more and more attention of researchers. With the discovery of various physical phenomena and structures in complex plasma systems, As a medium capable of simulating physical properties at the atomic level, its unique advantages have gradually emerged. Complex plasma experiments have evolved from initial ground experiments to experiments under microgravity. The development from element system to binary and multivariate system has experienced remarkable growth. PK-3 Plus, a more classical experimental device of the International Space Station, has been in service for many years, with rich research results. Complex plasma system is studying lattice, density wave, In the process of equalization correlation dynamics, it provides a unique angle of view and a different discovery for scholars. The phenomenon of wave transfer has been found in the experiment, and these waves are generated by self-excitation. Under certain experimental conditions, the existence of free energy is the prerequisite for the excitation of density waves. The microscopic study of these phenomena plays an important role in the explanation of many macroscopic phenomena. Due to the different forces of particles of different sizes in the system, the binary complex plasma system appears the process of independent phase separation. Smaller particles occupy the inner ring of the dust cloud, The larger and smaller particles separate and occupy the outer space of the dust cloud. There is a more obvious interfacial between the two particles in different regions. The density wave in the complex plasma system is due to its propagation. The seeding medium, that is, the dust particles, has different propagation frequencies. Therefore, the waves in binary system have different propagation frequencies in the inner circle of small particles and the outer circle of large particles. The propagation direction of density wave is spherical from the hole in the middle of dust cloud to the surrounding area. When waves with small particles as propagation medium propagate outward at a certain frequency to the interface, particles of different sizes collide with each other before and after the interface. The density wave is reflected back to the inner circle of the small particle by the frequency of the latter wave propagating in the large particle, and because of the dissipation of the whole system, Waves in the medium of small particles gradually dissipate and disappear as they travel to the region of large particles. In order to verify the existence of the reflected waves, we identify particles and make a kinetic energy periodic map of the particles. On the other hand, in order to understand the kinematics of the dust particles in the wave propagation, we have tracked the particles, and found that in a wave front propagation period, Large particles vibrate in a period, while small particles exhibit two periods of different amplitudes and different frequencies. The vibrational form of particles is affected by waves, when a single form of wave propagates to the medium, The medium vibrates at the frequency of the wave and the magnitude (amplitude) of the energy transmitted to it; when there are two forms of wave at the same time (the incident wave propagating in a positive direction in the experiment), The medium vibrates at the frequency and energy level (amplitude) of the wave, and then when another wave (the reflected wave in the experiment) propagates to the medium, the reflected wave is coupled with the incident wave. The whole process shows the characteristics of density wave propagation on the boundary surface and the function of the medium in the process of wave propagation.
【學(xué)位授予單位】：東華大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O53

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