本文選題：氧碘化學(xué)激光器 + 脈沖放電　； 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：脈沖氧碘化學(xué)激光器(COIL)與連續(xù)波氧碘化學(xué)激光器(CWCOIL)相比,不僅具有連續(xù)波氧碘化學(xué)激光器的優(yōu)勢(shì),而且自身還具有很多獨(dú)特的優(yōu)勢(shì),如激光所能穿透的深度更深、速度更快；具有較高能量的脈沖激光能夠進(jìn)行高效率的拉曼頻移,使激光的波長(zhǎng)具有可變動(dòng)性等。由于這些優(yōu)勢(shì)的存在,吸引了美國(guó)、俄羅斯、中國(guó)、日本等眾多國(guó)家的科研人員從事相關(guān)方面的研究。實(shí)現(xiàn)氧碘化學(xué)激光脈沖化的方法有很多,其中脈沖放電瞬間產(chǎn)生碘原子是最有發(fā)展前景的一種激光脈沖化技術(shù)。然而,到目前為止相關(guān)的實(shí)驗(yàn)研究基本上都局限在不同條件下對(duì)外部參量的觀測(cè)上,缺乏對(duì)產(chǎn)生脈沖激光的關(guān)鍵環(huán)節(jié)的研究,這使得人們?cè)趯?shí)驗(yàn)時(shí)存在一定的盲目性。與實(shí)驗(yàn)研究工作相比,相關(guān)的理論模擬工作非常少,在國(guó)外,目前見到的唯一報(bào)道是近年Kochetov等人的工作,但他們的模擬采用的是零維模型,因此無法給出放電過程中各種粒子的產(chǎn)生和消失過程等信息,而這些特性對(duì)放電引發(fā)COIL是非常關(guān)鍵的。本文將采用流體力學(xué)和動(dòng)力學(xué)混合模擬方法對(duì)放電引發(fā)脈沖COIL內(nèi)的脈沖放電過程進(jìn)行深入系統(tǒng)的研究。研究?jī)?nèi)容主要包括兩部分,第一部分為CF3I-O2-O2(a1△g)-He混合氣體脈沖放電性質(zhì)的研究,即研究了放電過程中電壓、電流特性,不同粒子密度的時(shí)空分布以及放電機(jī)制等。第二部分主要模擬研究了不同的放電參數(shù)(如電壓、脈寬、氣體配比等)對(duì)產(chǎn)生碘原子和激光效率的影響。研究結(jié)果期望為優(yōu)化放電引發(fā)脈沖COIL實(shí)驗(yàn)裝置,實(shí)現(xiàn)脈沖COIL的有效調(diào)控提供理論依據(jù)。模擬結(jié)果表明,CF3I-O2-O2(a1△g)-He混合氣體脈沖放電中存在等離子體鞘層區(qū)和等離子體正柱區(qū),因而具有明顯的輝光放電特征。脈沖放電生成的碘原子主要來源是高能電子與CF3I的直接碰撞解離反應(yīng)。此外,通過研究放電參數(shù)對(duì)碘原子密度的影響可以發(fā)現(xiàn)當(dāng)外加電壓幅值和脈沖寬度增加時(shí),碘原子的密度會(huì)隨之增加。在保持總氣壓和氧分壓不變的情況下,CF3I和He存在一個(gè)最佳的配比,在此配比下,產(chǎn)生的碘原子密度最大并且產(chǎn)生單個(gè)碘原子所需的能量也最少。模擬結(jié)果還顯示,碘原子的密度隨總氣壓的升高而降低。在總壓和氧壓固定的情況下,當(dāng)單重態(tài)氧的含量少于總氧含量的40%時(shí),粒子數(shù)反轉(zhuǎn)則不能形成,沒有激光輸出。
[Abstract]:Compared with CWCOILL, the pulsed oxygen-iodide chemical laser not only has the advantage of continuous wave oxygen-iodide chemical laser, but also has many unique advantages, for example, the laser can penetrate deeper depth and faster speed. The pulse laser with high energy can perform high efficiency Raman frequency shift, which makes the wavelength of the laser changeable and so on. As a result of these advantages, attracted the United States, Russia, China, Japan and many other countries to engage in scientific research. There are many methods to realize the pulse of oxygen-iodine chemical laser, among which the generation of iodine atom at the moment of pulse discharge is the most promising laser pulse technology. However, up to now, the related experimental studies are basically limited to the observation of external parameters under different conditions, and lack of research on the key link of producing pulsed laser, which makes people have certain blindness in the experiment. Compared with the experimental research work, the relevant theoretical simulation work is very few. In foreign countries, the only report seen at present is the work of Kochetov et al in recent years, but their simulation is based on zero dimensional model. Therefore, it is impossible to give the information about the generation and disappearance of various particles in the discharge process, and these characteristics are very important for the discharge initiation of COIL. In this paper, hydrodynamic and dynamic hybrid simulation methods are used to study the pulse discharge process in COIL. The first part is about the characteristics of CF3I-O2-O2(a1 g)-He mixed gas pulse discharge, that is, the characteristics of voltage, current, the space-time distribution of different particle density and the discharge mechanism. In the second part, the effects of different discharge parameters (such as voltage, pulse width, gas ratio, etc.) on the generation of iodine atoms and laser efficiency are studied. The results are expected to provide a theoretical basis for optimizing the experimental device of pulse COIL caused by discharge and realizing the effective regulation of pulse COIL. The simulation results show that the plasma sheath region and plasma positive column region exist in the mixed gas pulse discharge of CF3I-O _ 2-O _ 2O _ 2a _ 1 g)-He, so it has obvious glow discharge characteristics. The main source of iodine atoms generated by pulse discharge is the direct collision dissociation reaction between high energy electrons and CF3I. In addition, by studying the effect of discharge parameters on the density of iodine atoms, it can be found that the density of iodine atoms increases when the applied voltage amplitude and pulse width increase. Under the condition of keeping the total pressure and oxygen partial pressure constant, there is an optimum ratio of CF3I and he. Under this ratio, the density of iodine atom is the highest and the energy required to produce a single iodine atom is the least. The simulation results also show that the density of iodine atoms decreases with the increase of total pressure. In the case of fixed total pressure and oxygen pressure, when the content of singlet oxygen is less than 40% of the total oxygen content, the population inversion can not be formed and there is no laser output.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN248

【參考文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 李國(guó)富;氣體放電引發(fā)氧碘化學(xué)激光脈沖化及相關(guān)技術(shù)研究[D];大連理工大學(xué);2014年

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本文編號(hào)：1844264