高功率太赫茲回旋管準光模式變換器的研究
發(fā)布時間：2019-07-06 17:44
【摘要】：太赫茲(THz)科學技術(shù)是當前最受關(guān)注的國際學術(shù)前沿領(lǐng)域之一,為各國優(yōu)爭相搶占的科技制高點,它的發(fā)展對提高國家科技實力、促進國民經(jīng)濟發(fā)展、維護國土安全和社會安定都具有前瞻性、戰(zhàn)略性和全局性的重大意義。近年來,THz回旋管作為THz頻段高功率輻射源受到了廣泛關(guān)注,它解決了THz科學技術(shù)的發(fā)展和應(yīng)用受制于缺乏穩(wěn)定高效高功率THz輻射源的問題�；匦苁且环N典型的相對論電子學快波器件,它產(chǎn)生高功率THz波的原理是電子注在縱向磁場中回旋與高頻角向電場互相作用后產(chǎn)生受激輻射,又稱為電子回旋脈塞。在各國的努力下,回旋管朝著更高輸出功率和頻率的方向發(fā)展,它的工作模式通常要選用高階模式以增加諧振腔的功率容量、減少歐姆損耗。這種高階模式不利于THz波的遠距離傳輸和應(yīng)用,需要采用模式變換器將這些高階波導模式轉(zhuǎn)換成更利于傳輸?shù)牡碗A波導模式或者是高斯波束。由于傳統(tǒng)的波導模式變換器尺寸大不利于緊湊設(shè)計而且模式變換過程中模式競爭和損耗嚴重。而具有結(jié)構(gòu)簡單、設(shè)計緊湊和方便應(yīng)用等優(yōu)點的準光模式變換器現(xiàn)在已被廣泛使用,所以研究用于高功率THz回旋管的準光模式變換器具有非常重要的意義。本文首先對應(yīng)用于0.42THz-TE26模式和0.42THz-TE_(17,4)模式回旋管的準光模式變換器進行了理論和實驗研究,然后設(shè)計了能夠提高輸出光斑質(zhì)量的兩級相位校正鏡面,最后針對應(yīng)用于雙頻工作同軸雙電子注回旋管準光模式變換器進行了理論分析,并提出了運用基于頻率選擇表面(FSS)的空間濾波器能夠?qū)崿F(xiàn)輸出功率雙頻分離的方法。具體的研究內(nèi)容如下:1.從基本麥克斯韋方程組出發(fā),基于導波場理論和幾何光學近似,描述了回旋管工作模式在圓柱波導中的傳輸過程;結(jié)合矢量繞射理論和迭代方法,分析了應(yīng)用于0.42THz-TE26模式回旋管準光模式變換器中Vlasov型輻射器場結(jié)構(gòu),數(shù)值計算結(jié)果與三維電磁場全波仿真軟件—FEKO的模擬結(jié)果吻合良好。2.基于傳輸線理論和阻抗微擾理論,推導出考慮返波作用的耦合波方程,并分析了應(yīng)用于0.42THz-TE_(17,4)模式回旋管準光模式變換器中Denisov型輻射器擾動段電磁波耦合情況及輻射器場結(jié)構(gòu),且數(shù)值計算結(jié)果與FEKO模擬結(jié)吻合良好。3.運用幾何光學理論,推導了滿足匯聚要求的準橢圓鏡和拋物鏡面在全局坐標系下鏡面方程;基于矢量繞射理論,計算了各個規(guī)則鏡面及輸出窗處的場分布并與FEKO模擬結(jié)果進行對比驗證;結(jié)合KSA算法和矢量繞射理論,設(shè)計出了能很大程度提高輸出光斑質(zhì)量的兩級相位校正鏡,且數(shù)值計算結(jié)果與FEKO模擬結(jié)吻合良好。4.對應(yīng)用于0.42THz-TE26模式和0.42THz-TE_(17,4)模式回旋管的準光模式變換器進行了實驗研究,其中輻射器分別為Vlasov型和Denisov型,實驗測試所得結(jié)果與理論預(yù)測值吻合良好。5.首先介紹了雙頻工作同軸雙電子注回旋管工作原理以及相應(yīng)的模擬結(jié)果,并進行了相關(guān)實驗測試,實驗結(jié)果表明,基波和二次諧波同時工作的狀態(tài)得到驗證;然后針對雙頻工作同軸雙電子注回旋振蕩管同時輸出的兩個模式,分析了運用同一階梯型準光模式變換器的模式轉(zhuǎn)換情況;最后提出了運用基于頻率選擇表面空間濾波器能夠?qū)崿F(xiàn)輸出功率雙頻分離的方法,運用THz時域光譜儀(TDS)對加工出的樣品進行初步測試,并給出了透射系數(shù)的測量結(jié)果。
文內(nèi)圖片：
圖片說明：電磁波譜分布圖
[Abstract]:Terahertz (THz) science and technology is one of the most important international academic front areas of the world, and it is a high-tech high point for all countries to seize, and its development is forward-looking for improving the national scientific and technological strength, promoting the development of the national economy, safeguarding the homeland security and social stability, Strategic and global significance. In recent years, the THz gyrotron is widely concerned as the high-power radiation source in the THz frequency band, which solves the problems of the development and application of THz technology in the absence of a stable and high-power THz radiation source. The gyrotron is a typical relativistic electronic fast wave device. The principle of high power THz wave is that the electron injection generates excited radiation in the longitudinal magnetic field and the high-frequency angle to the electric field, and is also called electron cyclotron masse. In the efforts of all countries, the gyrotron is developed in the direction of higher output power and frequency, and its working mode is usually high-order mode to increase the power capacity of the resonant cavity and reduce the ohmic loss. This high-order mode is detrimental to the long-distance transmission and application of THz waves, and it is necessary to use a mode converter to convert these high-order waveguide modes into a low-order waveguide mode that is more favorable for transmission or a Gaussian beam. Due to the large size of the traditional waveguide mode converter, the mode competition and the loss are serious in the process of the compact design and the mode transformation process. The quasi-optical mode converter with the advantages of simple structure, compact design and convenient application has been widely used, so it is very important to study the quasi-optical mode converter for high power THz gyrotron. In this paper, the quasi-optical mode converter for 0.42 THz-TE26 and 0.42 THz-TE _ (17,4) mode gyrotron is studied theoretically and experimentally, and a two-stage phase correction mirror which can improve the quality of the output spot is designed. In the end, the theoretical analysis of the quasi-optical mode converter applied to the dual-frequency dual-frequency dual-electron-injection gyrotron is put forward, and the method of using the space filter based on the frequency selective surface (FSS) to realize double-frequency separation of the output power is put forward. The specific content of the study is as follows:1. Based on the theory of guided wave field and the geometrical optics approximation, the transmission process of the working mode of the gyrotron in the cylindrical waveguide is described from the basic Maxwell equations, and the vector diffraction theory and the iterative method are combined. The Vlasov type radiator field structure in a 0.42 THz-TE26 mode gyrotron quasi-optical mode converter is analyzed, and the numerical results are in good agreement with the simulation results of the three-dimensional electromagnetic field full-wave simulation software. Based on the theory of transmission line and the theory of impedance perturbation, the coupling wave equation considering the function of the return wave is derived, and the electromagnetic coupling and the structure of the radiator field of the Denisov type radiator in the quasi-optical mode converter with the mode of 0.42 THz-TE _ (17,4) are analyzed. And the numerical results are in good agreement with the FEKO simulation. The mirror equation of the quasi-elliptical mirror and the parabolic mirror in the global coordinate system is derived by using the geometrical optics theory, and the field distribution at each regular mirror and the output window is calculated based on the vector diffraction theory and compared with the FEKO simulation result. Combined with the KSA algorithm and the vector diffraction theory, a two-stage phase correction mirror which can improve the output spot quality is designed to a great extent, and the numerical results are in good agreement with the FEKO analog junction. The quasi-optical mode converter for 0.42 THz-TE26 mode and 0.42 THz-TE _ (17,4) mode gyrotron has been experimentally studied, in which the radiators are Vlasov type and Denisov type, and the results of the experimental test are in good agreement with the theoretical predicted value. In this paper, the working principle and the corresponding simulation results of the dual-frequency working coaxial double-electron beam-injection tube are introduced. The experimental results show that the state of the simultaneous operation of the fundamental wave and the second harmonic is verified. then the mode conversion of the same step-type quasi-optical mode converter is analyzed for two modes simultaneously output by the dual-frequency working coaxial dual-electron beam-injection rotary oscillation tube, and finally, a method for realizing double-frequency separation of the output power by using a frequency-based selection surface spatial filter is proposed, The processed samples were tested with a THz time-domain spectrometer (TDS), and the results of the measurements were given.
【學位授予單位】：電子科技大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TN12
文內(nèi)圖片：
圖片說明：電磁波譜分布圖
[Abstract]:Terahertz (THz) science and technology is one of the most important international academic front areas of the world, and it is a high-tech high point for all countries to seize, and its development is forward-looking for improving the national scientific and technological strength, promoting the development of the national economy, safeguarding the homeland security and social stability, Strategic and global significance. In recent years, the THz gyrotron is widely concerned as the high-power radiation source in the THz frequency band, which solves the problems of the development and application of THz technology in the absence of a stable and high-power THz radiation source. The gyrotron is a typical relativistic electronic fast wave device. The principle of high power THz wave is that the electron injection generates excited radiation in the longitudinal magnetic field and the high-frequency angle to the electric field, and is also called electron cyclotron masse. In the efforts of all countries, the gyrotron is developed in the direction of higher output power and frequency, and its working mode is usually high-order mode to increase the power capacity of the resonant cavity and reduce the ohmic loss. This high-order mode is detrimental to the long-distance transmission and application of THz waves, and it is necessary to use a mode converter to convert these high-order waveguide modes into a low-order waveguide mode that is more favorable for transmission or a Gaussian beam. Due to the large size of the traditional waveguide mode converter, the mode competition and the loss are serious in the process of the compact design and the mode transformation process. The quasi-optical mode converter with the advantages of simple structure, compact design and convenient application has been widely used, so it is very important to study the quasi-optical mode converter for high power THz gyrotron. In this paper, the quasi-optical mode converter for 0.42 THz-TE26 and 0.42 THz-TE _ (17,4) mode gyrotron is studied theoretically and experimentally, and a two-stage phase correction mirror which can improve the quality of the output spot is designed. In the end, the theoretical analysis of the quasi-optical mode converter applied to the dual-frequency dual-frequency dual-electron-injection gyrotron is put forward, and the method of using the space filter based on the frequency selective surface (FSS) to realize double-frequency separation of the output power is put forward. The specific content of the study is as follows:1. Based on the theory of guided wave field and the geometrical optics approximation, the transmission process of the working mode of the gyrotron in the cylindrical waveguide is described from the basic Maxwell equations, and the vector diffraction theory and the iterative method are combined. The Vlasov type radiator field structure in a 0.42 THz-TE26 mode gyrotron quasi-optical mode converter is analyzed, and the numerical results are in good agreement with the simulation results of the three-dimensional electromagnetic field full-wave simulation software. Based on the theory of transmission line and the theory of impedance perturbation, the coupling wave equation considering the function of the return wave is derived, and the electromagnetic coupling and the structure of the radiator field of the Denisov type radiator in the quasi-optical mode converter with the mode of 0.42 THz-TE _ (17,4) are analyzed. And the numerical results are in good agreement with the FEKO simulation. The mirror equation of the quasi-elliptical mirror and the parabolic mirror in the global coordinate system is derived by using the geometrical optics theory, and the field distribution at each regular mirror and the output window is calculated based on the vector diffraction theory and compared with the FEKO simulation result. Combined with the KSA algorithm and the vector diffraction theory, a two-stage phase correction mirror which can improve the output spot quality is designed to a great extent, and the numerical results are in good agreement with the FEKO analog junction. The quasi-optical mode converter for 0.42 THz-TE26 mode and 0.42 THz-TE _ (17,4) mode gyrotron has been experimentally studied, in which the radiators are Vlasov type and Denisov type, and the results of the experimental test are in good agreement with the theoretical predicted value. In this paper, the working principle and the corresponding simulation results of the dual-frequency working coaxial double-electron beam-injection tube are introduced. The experimental results show that the state of the simultaneous operation of the fundamental wave and the second harmonic is verified. then the mode conversion of the same step-type quasi-optical mode converter is analyzed for two modes simultaneously output by the dual-frequency working coaxial dual-electron beam-injection rotary oscillation tube, and finally, a method for realizing double-frequency separation of the output power by using a frequency-based selection surface spatial filter is proposed, The processed samples were tested with a THz time-domain spectrometer (TDS), and the results of the measurements were given.
【學位授予單位】：電子科技大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TN12
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