太赫兹回旋管准光模式变换器的研究
发布时间：2018-07-25 12:54
【摘要】：太赫兹波介于毫米波和红外之间,它的产生和应用是目前国际上的一个研究热点。回旋管已经被证明是最有可能产生大功率太赫兹信号的器件。太赫兹波为亚毫米波,其波长很短,在波导中传输损耗大。为增大注-波互作用腔体的尺寸,太赫兹回旋管通常工作于高阶模式。然而高阶模式电磁波不利于在自由空间中传输和应用,因此为了增大回旋管的收集极半径,提高输出功率,需要采用准光模式变换器横向输出太赫兹波。采用准光模式变换器可以减少输出窗的反射,防止反射波加热电子注从而影响注-波互作用的稳定性。因此,研究太赫兹回旋管准光模式变换器具有非常重要的意义。本文首先对W波段回旋管的准光模式变换器进行理论研究和实验,然后对工作于高阶旋转模式TE17,4,输出频率为0.42THz的回旋管准光模式变换器进行研究分析。本文的主要内容和创新之处可概述如下:1、采用正弦幅度曲线代替了传统的梯形折线幅度曲线设计了太赫兹波的Denisov辐射器。Denisov辐射器是Vlasov辐射器改进型结构,它采用了一段壁扰动波导结构对输入的电磁波进行预聚束成类高斯束分布。扰动结构通常采用螺旋波纹形式,扰动深度沿传播方向成梯形折线分布,这种分布结构在折线的拐点处存在奇点。奇点的存在使波导内耦合系数的推导与数值计算带来了困难。本文采用的正弦幅度曲线存在连续偏导数,避免了奇点的存在,减少了计算难度,同时也减小了寄生模式。2、采用矢量绕射积分法计算了辐射口输出的辐射场,辐射场分布与给出的实验结果基本一致。高阶模式输入的辐射器采用螺旋切口结构,电磁波从螺旋切口向外辐射,辐射场的功率和效率是影响整个准光模式变换器的性能的主要因素。因此需要精确计算辐射口的场分布。目前国际上主要采用三维仿真软件进行仿真分析,但随着工作模式和频率的提高,三维仿真软件需要大量的计算机资源和时间。矢量绕射积分法既可以满足计算精度的要求也可以大大减小计算机资源和缩短计算时间。3、矢量绕射积分法与标量绕射积分法相结合计算各个反射镜面上的场分布。标量绕射积分法具有计算量小,计算速度快等优点,但由于忽略了镜面边沿上的场分布,计算精度被降低了。矢量绕射积分法计算量大,精度高。本文结合两者的优点,先采用标量绕射积分法计算出各个镜面的位置和尺寸,再采用矢量绕射法精确计算镜面上的场分布和精确调整反射面的各个几何参数。4、设计了工作于0.1THz TE6,2的太赫兹准光模式变换器。在传统的扰动方程的基础上增加了多项扰动因子,增强了扰动结构的灵活性。采用耦合波理论计算了扰动段内各个模式沿纵向的功率分布,分析了辐射口的高斯束参数,分析了输出电磁波的旋转方向对模式变换器的转换效率和功率的影响。结合本文所依赖的课题,采用四个反射镜对输出的辐射场进行相位修正。5、设计了工作于0.42THz TE17,4高阶模式高过模的太赫兹回旋管准光模式变换器。由于工作模式很高,可能存在很多的寄生模式,需要分析波导内可能耦合出的各个寄生模式,从而采用相应的措施抑制寄生模式。太赫兹波长很短,波导截止半径很小,因此回旋管收集极工作于高过模状态,不适合采用Denisov辐射器直接转换,需要一节过渡波导把收集极半径进行适当的收缩,然后再输入到准光模式变换器内进行模式转换。6、对所设计的准光模式变换器进热测实验。准光模式变换器是准光输出回旋管的重要组成部分,是为便于后级应用和增加降压收集极作为充分的准备。本文设计的准光模式变换顺增补了国内的空白,研制出了国内第一支准光输出高功率回旋管。
[Abstract]:Terahertz wave is between the millimeter wave and the infrared, and its production and application are a hot spot of research in the world. The gyrotron has been proved to be the most likely device to produce high power terahertz signals. The terahertz wave is submillimeter wave, its wavelength is very short, and the transmission loss is large in the waveguide. It is too large to increase the size of the cavity of the injection wave interaction. The Hertzian gyrotron usually works in the high order mode. However, the high order mode electromagnetic wave is not conducive to the transmission and application in the free space. Therefore, in order to increase the collector radius and increase the output power of the gyrotron, the quasi optical mode converter is needed to output the terahertz wave laterally. It is very important to study the quasi optical mode converter of the terahertz gyrotron. This paper first studies and experiments on the quasi optical mode converter of the W band gyrotron, and then works on the high order rotation mode TE17,4, and the output frequency is 0.42THz. The main contents and innovations of this paper can be summarized as follows: 1, using the sinusoidal amplitude curve instead of the traditional trapezoid fold line amplitude curve, the Denisov radiator.Denisov radiator of the terahertz wave is an improved structure of the Vlasov radiator, and it adopts a wall disturbance waveguide structure. The input electromagnetic wave is preclustered into Gauss beam distribution. The disturbance structure usually uses the form of spiral ripple. The disturbance depth is trapezoid fold along the direction of propagation. This distribution structure has odd points at the turning point of the folded line. The existence of singularity brings difficulties to the deduction of the coupling coefficient in the waveguide and the numerical calculation. There is a continuous partial derivative of the string amplitude curve, which avoids the existence of the singularities, reduces the difficulty of calculation, and reduces the parasitic mode.2. The radiation field is calculated by the vector diffraction integral method. The distribution of the radiation field is basically the same as the experimental results. The high order model input radiator uses a spiral incision structure and electromagnetic wave. The power and efficiency of the radiation field are the main factors affecting the performance of the whole quasi optical mode converter. Therefore, it is necessary to accurately calculate the field distribution of the radiant port. At present, the three dimensional simulation software is mainly used in the simulation and analysis in the world. But with the improvement of the working mode and frequency, the three-dimensional simulation software needs a large amount. The vector diffraction integral method can not only satisfy the requirement of calculation precision, but also greatly reduce the computer resources and shorten the calculation time.3. The vector diffraction integral method and the scalar diffraction integral method are combined to calculate the field distribution on the mirror surface. The scalar diffraction product method has the advantages of small calculation, fast calculation and so on. But because of neglecting the field distribution on the edge of the mirror, the calculation precision is reduced. The vector diffraction integral method has a large calculation and high precision. In this paper, the position and size of the mirror surface are calculated by the scalar diffraction integral method, and the vector diffraction method is used to accurately calculate the field distribution on the mirror surface and the precise adjustment of the reflector. Each geometric parameter.4 is designed for the terahertz quasi optical mode converter working in 0.1THz TE6,2. On the basis of the traditional perturbation equation, a number of disturbance factors are added to enhance the flexibility of the disturbance structure. The coupling wave theory is used to calculate the longitudinal power distribution of each mode in the disturbance section, and the Gauss beam parameter of the radiant port is analyzed. The influence of the rotation direction of the output electromagnetic wave on the conversion efficiency and power of the mode converter is analyzed. Combined with the subject of this paper, four mirrors are used to correct the output of the radiation field by phase correction.5. A quasi optical mode converter working in the high mode high mode 0.42THz TE17,4 mode high mode overmodel is designed. The mode is very high, and there may be many parasitic modes. It is necessary to analyze the parasitic modes that may be coupled in the waveguide, so that the corresponding measures can be used to suppress the parasitic mode. The terahertz wavelength is very short and the cut-off radius of the waveguide is very small. Therefore, the collector of the gyrotron works on the high overmode state, and is not suitable for direct conversion of the Denisov radiator. In a transition waveguide, the collector radius is properly contracted and then entered into the quasi optical mode converter to carry out the mode conversion.6, and the design of the quasi optical mode converter is put into heat test. The quasi optical mode converter is an important part of the quasi optical output gyrotron, which is used for the post stage application and the increase of the depressurization collector. The quasi optical mode transformation designed in this paper has supplemented the domestic blank and developed the first quasi optical output high power gyrotron in China.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN12
[Abstract]:Terahertz wave is between the millimeter wave and the infrared, and its production and application are a hot spot of research in the world. The gyrotron has been proved to be the most likely device to produce high power terahertz signals. The terahertz wave is submillimeter wave, its wavelength is very short, and the transmission loss is large in the waveguide. It is too large to increase the size of the cavity of the injection wave interaction. The Hertzian gyrotron usually works in the high order mode. However, the high order mode electromagnetic wave is not conducive to the transmission and application in the free space. Therefore, in order to increase the collector radius and increase the output power of the gyrotron, the quasi optical mode converter is needed to output the terahertz wave laterally. It is very important to study the quasi optical mode converter of the terahertz gyrotron. This paper first studies and experiments on the quasi optical mode converter of the W band gyrotron, and then works on the high order rotation mode TE17,4, and the output frequency is 0.42THz. The main contents and innovations of this paper can be summarized as follows: 1, using the sinusoidal amplitude curve instead of the traditional trapezoid fold line amplitude curve, the Denisov radiator.Denisov radiator of the terahertz wave is an improved structure of the Vlasov radiator, and it adopts a wall disturbance waveguide structure. The input electromagnetic wave is preclustered into Gauss beam distribution. The disturbance structure usually uses the form of spiral ripple. The disturbance depth is trapezoid fold along the direction of propagation. This distribution structure has odd points at the turning point of the folded line. The existence of singularity brings difficulties to the deduction of the coupling coefficient in the waveguide and the numerical calculation. There is a continuous partial derivative of the string amplitude curve, which avoids the existence of the singularities, reduces the difficulty of calculation, and reduces the parasitic mode.2. The radiation field is calculated by the vector diffraction integral method. The distribution of the radiation field is basically the same as the experimental results. The high order model input radiator uses a spiral incision structure and electromagnetic wave. The power and efficiency of the radiation field are the main factors affecting the performance of the whole quasi optical mode converter. Therefore, it is necessary to accurately calculate the field distribution of the radiant port. At present, the three dimensional simulation software is mainly used in the simulation and analysis in the world. But with the improvement of the working mode and frequency, the three-dimensional simulation software needs a large amount. The vector diffraction integral method can not only satisfy the requirement of calculation precision, but also greatly reduce the computer resources and shorten the calculation time.3. The vector diffraction integral method and the scalar diffraction integral method are combined to calculate the field distribution on the mirror surface. The scalar diffraction product method has the advantages of small calculation, fast calculation and so on. But because of neglecting the field distribution on the edge of the mirror, the calculation precision is reduced. The vector diffraction integral method has a large calculation and high precision. In this paper, the position and size of the mirror surface are calculated by the scalar diffraction integral method, and the vector diffraction method is used to accurately calculate the field distribution on the mirror surface and the precise adjustment of the reflector. Each geometric parameter.4 is designed for the terahertz quasi optical mode converter working in 0.1THz TE6,2. On the basis of the traditional perturbation equation, a number of disturbance factors are added to enhance the flexibility of the disturbance structure. The coupling wave theory is used to calculate the longitudinal power distribution of each mode in the disturbance section, and the Gauss beam parameter of the radiant port is analyzed. The influence of the rotation direction of the output electromagnetic wave on the conversion efficiency and power of the mode converter is analyzed. Combined with the subject of this paper, four mirrors are used to correct the output of the radiation field by phase correction.5. A quasi optical mode converter working in the high mode high mode 0.42THz TE17,4 mode high mode overmodel is designed. The mode is very high, and there may be many parasitic modes. It is necessary to analyze the parasitic modes that may be coupled in the waveguide, so that the corresponding measures can be used to suppress the parasitic mode. The terahertz wavelength is very short and the cut-off radius of the waveguide is very small. Therefore, the collector of the gyrotron works on the high overmode state, and is not suitable for direct conversion of the Denisov radiator. In a transition waveguide, the collector radius is properly contracted and then entered into the quasi optical mode converter to carry out the mode conversion.6, and the design of the quasi optical mode converter is put into heat test. The quasi optical mode converter is an important part of the quasi optical output gyrotron, which is used for the post stage application and the increase of the depressurization collector. The quasi optical mode transformation designed in this paper has supplemented the domestic blank and developed the first quasi optical output high power gyrotron in China.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN12
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