本文選題：THz波 + NH3　； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：THz波位于電磁波譜中微波和紅外波之間,屬于亞毫米波。由于其性質(zhì)十分獨特,能穿透非金屬、非極性材料、煙霧和浮塵等且不造成傷害,并且能夠識別生物大分子,因此,研究高能量轉(zhuǎn)化效率的THz源意義重大。本論文從提高光泵氣體THz激光器的能量轉(zhuǎn)化效率方面入手,利用TEA CO2激光器作為泵浦源,利用NH3(氨氣)氣體作為工作介質(zhì),從理論和實驗方面對能量轉(zhuǎn)化效率隨泵浦能量和氣體壓強的變化規(guī)律進行了初步研究。理論方面,建立了三能級速率方程理論模型,采用四階Rung-Kutta法,利用MATLAB程序進行數(shù)值仿真,從激光產(chǎn)生機理的角度分析了泵浦能量和氣體壓強對各能級粒子數(shù)以及THz光子數(shù)的影響。在特定氣壓下,研究了能量轉(zhuǎn)化效率隨泵浦能量的變化規(guī)律,得到能量轉(zhuǎn)化效率的最大值為0.3%,且在泵浦能量為200m J~1J范圍內(nèi)基本維持不變,在0~200m J以及1~50J,能量轉(zhuǎn)化效率均低于0.3%;在特定泵浦能量下,研究了能量轉(zhuǎn)化效率隨氣體壓強的變化規(guī)律,得到能量轉(zhuǎn)化效率最大值處對應(yīng)的氣壓為550Pa,并考慮了泵浦光在NH3氣體中的吸收過程對氣體壓強及能量轉(zhuǎn)化效率的影響。實驗方面,設(shè)計并搭建了光泵NH3氣體超輻射THz激光器,測試了泵浦源TEA CO2激光器的性能;研究了TEA CO2激光器的9R(16)支線及其兩側(cè)支線9R(14)支線和9R(18)支線在NH3氣體中的吸收特性。在特定氣壓下,研究了能量轉(zhuǎn)化效率隨泵浦能量的變化規(guī)律,得到了能量轉(zhuǎn)化效率隨泵浦能量呈線性增長規(guī)律,并且在泵浦能量為200m J時,獲得能量轉(zhuǎn)化效率最大值為0.4%;在特定泵浦能量下,研究了能量轉(zhuǎn)化效率隨氣體壓強的變化規(guī)律,得到能量轉(zhuǎn)化效率最大值處對應(yīng)的氣壓約為550Pa。對比了理論與實驗關(guān)于能量轉(zhuǎn)化效率的研究,對誤差產(chǎn)生的原因進行了分析,并指出了理論模型的優(yōu)缺點及后續(xù)研究的方向。
[Abstract]:THz wave lies between microwave and infrared wave in electromagnetic spectrum and belongs to submillimeter wave.Because of its unique properties, it can penetrate non-metallic, non-polar materials, smoke and floating dust without causing harm, and can recognize biological macromolecules, so it is of great significance to study the THz source with high energy conversion efficiency.In this paper, the energy conversion efficiency of the optically pumped gas THz laser is improved. The TEA CO2 laser is used as the pump source and the NH _ 3 (ammonia) gas as the working medium.The variation of energy conversion efficiency with pump energy and gas pressure is studied theoretically and experimentally.In theory, a theoretical model of three-level rate equation is established, and the four-order Rung-Kutta method is used to carry out numerical simulation by using MATLAB program.The effects of pump energy and gas pressure on the number of particles and THz photons at different levels are analyzed from the point of view of laser generation mechanism.The variation of energy conversion efficiency with pump energy is studied at specific pressure. The maximum energy conversion efficiency is 0.3, and the energy conversion efficiency remains unchanged in the range of 200m J ~ (-1) J.The energy conversion efficiency is lower than 0.3 at 0 ~ 200 MJ and 1 ~ 50 J, and the variation of energy conversion efficiency with gas pressure is studied under the specific pump energy.The pressure corresponding to the maximum energy conversion efficiency is 550 Pa. the influence of the absorption process of pump light in NH3 gas on the gas pressure and energy conversion efficiency is considered.In the aspect of experiment, the optical pump NH3 gas superradiance THz laser is designed and constructed, the performance of the pump source TEA CO2 laser is tested, and the absorption characteristics of the TEA CO2 laser's 9RN16) branch line and its two sides branch line 9RGN 14) and the 9RN 18) branch line in NH3 gas are studied.The variation of energy conversion efficiency with pump energy is studied at a specific pressure. The energy conversion efficiency increases linearly with pump energy, and when the pump energy is 200 MJ, the energy conversion efficiency increases linearly with pump energy.The maximum energy conversion efficiency is 0.4.The variation of energy conversion efficiency with gas pressure is studied under the specific pump energy, and the pressure corresponding to the maximum energy conversion efficiency is about 550 Pa.This paper compares the theoretical and experimental studies on energy conversion efficiency, analyzes the causes of errors, and points out the advantages and disadvantages of the theoretical model and the direction of further research.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN248.22

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