本文關鍵詞：帶狀束新型螺旋線行波管的研究　出處：《電子科技大學》2016年博士論文　論文類型：學位論文

  更多相關文章： 螺旋線 帶狀束 慢波結構 行波管

【摘要】：更高的工作頻率和更大的輸出功率是行波管發(fā)展的兩個主要目標。傳統(tǒng)的圓螺旋線慢波結構因為具有超寬的工作頻帶、較高的互作用阻抗以及高增益等優(yōu)點,在寬帶中等功率行波管以及微波功率模塊等領域獲得廣泛應用。然而,當行波管工作頻率上升到V波段及以上頻段時,慢波結構的尺寸變得非常小,圓螺旋線的三維結構本質使得其精確加工變得困難,同時電子注通道半徑也隨著工作頻率提高被急劇壓縮,這些因素極大地限制了圓螺旋線行波管在更高頻段場合的應用。為適應行波管高頻工作的發(fā)展趨勢,研究人員提出了矩形螺旋線慢波結構,并基于螺旋導面模型(Sheath Model)對該平面慢波結構的高頻特性進行了理論分析,推導得出了基于螺旋導面模型的色散方程,所得結論具有一定的指導意義。然而,基于螺旋導面模型的分析方法忽略了矩形螺旋線周期結構的本質,沒有考慮實際螺旋帶寬度以及空間諧波對慢波系統(tǒng)高頻特性的影響,因而不能反映該結構周期性通帶和阻帶的特點,在理論處理方法上有所欠缺,同時在色散方程計算的準確性也需要提高。作為一種有著良好應用前景的螺旋類慢波結構,迫切需要更準確的理論來指導矩形螺旋線行波管實際的設計與加工。為此,本論文在前人簡化模型的基礎上,采用更準確的螺旋導帶模型(Tape Model)對矩形螺旋線中電磁波的傳播特性進行了深入的研究,在嚴格電磁理論分析基礎上建立了基于周期系統(tǒng)模型的矩形螺旋線色散方程,更準確地掌握了電磁波在矩形螺旋線慢波結構中的傳播規(guī)律,為矩形螺旋線行波管的設計與加工提供了更可靠的理論指導。另一方面,現(xiàn)有的圓螺旋線行波管普遍采用圓形電子注為能量源,而圓形電子注固有的強空間電荷效應制約了行波管輸出功率的進一步提高。為提高現(xiàn)有圓螺旋線行波管的輸出功率,需要探索圓螺旋線慢波結構與帶狀電子注互作用的有效結構及相應的工作機理。為此,本論文分析了圓波導加載內偏心圓螺旋線慢波結構,基于嚴格的電磁理論分析建立了該偏心慢波系統(tǒng)的特征方程,研究了偏心距離等參數(shù)對慢波系統(tǒng)色散和互作用阻抗的影響,為多個圓螺旋線慢波結構與帶狀電子注的互作用研究奠定了前期理論基礎。本論文的主要研究內容分為以下幾部分:1.為了更準確地理解矩形螺旋線慢波結構的電磁特性,基于螺旋導帶模型,對自由矩形螺旋線慢波結構進行了深入的理論分析。在對矩形螺旋線中面電流展開的基礎上,綜合應用功率流匹配法和修正的Marcatili法,推導得出了基于周期系統(tǒng)模型的矩形螺旋線色散方程和互作用阻抗解析表達式。與HFSS的仿真結果對比表明基于周期系統(tǒng)理論的矩形螺旋線色散方程具有更高的計算準確性,可以更準確地預測電磁波在矩形螺旋線中的傳播規(guī)律。上述結果有利于深入了解自由空間矩形螺旋線的高頻特性,為其在寬帶毫米波行波管的應用奠定了理論基礎。2.研究了加載電介質和外接屏蔽腔的矩形螺旋線慢波結構,基于螺旋導帶模型,理論推導了介質加載和存在屏蔽腔情形下矩形螺旋線的色散方程和互作用阻抗表達式。數(shù)值計算了正常和反常加載情況下矩形螺旋線結構的高頻特性,并與HFSS仿真結果以及工作于S波段的矩形螺旋線實驗結果進行了對比。結果顯示,基于螺旋導帶模型的色散方程具有更高的準確性,該色散方程對介質參數(shù)和屏蔽腔尺寸對高頻特性的影響有著更準確的預測。3.基于注-波互作用線性理論,在螺旋導帶模型下,分析得出了矩形螺旋線行波管橫向反對稱模的熱色散方程。數(shù)值計算了螺旋線結構參數(shù)和電子注參數(shù)對行波管增益和工作帶寬的影響。結果表明,在相同的電子注參數(shù)下,方形螺旋線行波管比等價圓螺旋線(相同的橫截面周長和螺距角)行波管具有更高的增益,但工作帶寬則小于等價圓螺旋線行波管,而中高寬高比的矩形螺旋線行波管卻具有增益和帶寬上的綜合優(yōu)勢。4.作為多個圓螺旋線慢波結構與帶狀電子注互作用的基礎理論工作,我們分析了圓波導加載內偏心圓螺旋線慢波結構�；趪栏竦碾姶爬碚摲治�,利用螺旋線模式的正交性和變態(tài)貝塞爾函數(shù)的加法定理,推導得出了該偏心慢波系統(tǒng)的特征方程。結果表明,單一的正態(tài)螺旋線模式不能同時滿足系統(tǒng)的內外邊界條件,該偏心慢波結構的場解為多個混合模式的疊加。數(shù)值計算表明,偏心距離的出現(xiàn)降低了慢波結構主模在低頻段的歸一化相速和互作用阻抗,而中高頻段的色散與耦合阻抗受偏心位移的影響較小。上述結果有利于深入了解偏心螺旋線慢波結構的高頻特性,為多個圓螺旋線慢波結構與帶狀電子束的互作用研究奠定了前期理論基礎。
[Abstract]:Higher working frequency and greater output power are the two main objectives of the development of the TWT. The traditional circular helix slow wave structure is widely applied in broadband, medium power traveling wave tube and microwave power module because of its wide bandwidth, high interaction impedance and high gain. However, when the rise of the TWT frequency to the V band and above the band, the slow wave structure size becomes very small, the three-dimensional structure of the essence of helix makes its precision machining difficult, while the electron beam radius with the working frequency channel is improved sharply compression, these factors greatly limit the application of helix the traveling wave tube in higher frequency applications. In order to adapt to the development trend of high frequency traveling wave tube, the researchers put forward the rectangular helix slow wave structure, and based on the spiral guide surface model (Sheath Model) on the high frequency characteristics of the planar slow wave structure is analyzed and deduced from the dispersion equation of spiral surface based model, the conclusion is the guidance. However, analysis method of spiral surface model based on ignoring the essence of rectangular helical periodic structure, without considering the spiral band width and space harmonic effect on the frequency characteristics of slow wave system, which does not reflect the characteristics of the periodic structure of passband and stopband, lacking in the theory of processing method, the accuracy at the same time in the calculation of the dispersion equation also needs to improve. As a kind of spiral slow wave structure with good application prospects, more accurate theory is urgently needed to guide the actual design and processing of the rectangular helix traveling wave tube. Therefore, in this paper the simplified model, the spiral model is more accurate than the conduction band (Tape Model) on the propagation characteristic of electromagnetic wave in rectangular helix is studied, in the strict electromagnetic theory analysis is established based on dispersion moment spiral cycle system model based on the equation, more accurately grasp the electromagnetic wave in the rectangular helix slow wave propagation structure, rectangular helix TWT design and processing provides a more reliable theoretical guidance. On the other hand, the existing circular helix traveling wave tubes generally use circular electron beam as energy source, while the inherent strong space charge effect of the round electron beam restricts the further improvement of the output power of the TWT. In order to improve the output power of the existing circular helix traveling wave tube, we need to explore the effective structure and the corresponding working mechanism of the interaction between the circular helix slow wave structure and the strip electron beam. Therefore, this paper analyzes the circular waveguide loaded in eccentric helical slow wave structure, the electromagnetic characteristic equation of strict theoretical analysis established the eccentric slow wave system based on the study of the influence of parameters of eccentric distance on the slow wave dispersion and interaction impedance, multiple circular helix slow laid early the theoretical basis of the interaction of wave structure and sheet electron beam. The main research contents of this paper are divided into the following parts: 1.. In order to understand the electromagnetic characteristics of the rectangular helical slow wave structure more accurately, based on the spiral conduction band model, the theoretical analysis of the free rectangular helix slow wave structure is carried out. Based on the expansion of the middle surface of the rectangle spiral line, the power flow matching method and the modified Marcatili method are applied synthetically, and the dispersion equation and the interaction impedance expression of the rectangular helix are derived based on the periodic system model. Compared with the simulation results of HFSS, it is shown that the dispersion equation based on the theory of periodic system has higher accuracy and can predict the propagation of electromagnetic waves in a rectangular spiral. The above results are helpful to understand the high frequency characteristics of the rectangular spiral line in free space, and lay a theoretical foundation for its application in the broadband millimeter wave traveling wave tube. 2., the rectangular helix slow wave structure loaded with dielectric and external shielding cavity is studied. Based on the spiral conduction band model, the dispersion equation and interaction impedance expression of the rectangular helix under the condition of dielectric loading and shielding cavity are derived theoretically. The high frequency characteristics of the rectangular helical structure under normal and abnormal loading are numerically calculated, and compared with the HFSS simulation results and the experimental results of the rectangular helix in S band. The results show that the dispersion equation based on the spiral conduction band model has higher accuracy. The dispersion equation has a more accurate prediction of the influence of the medium parameters and the size of the shielding chamber on the high-frequency characteristics. 3. based on the linear theory of injection wave interaction, the thermal dispersion equation of the transverse anti symmetric mode of a rectangular spiral traveling wave tube is obtained under the model of the spiral guide band. The effects of the structural parameters and the electron beam parameters on the gain and bandwidth of the TWT are numerically calculated. The results show that the parameters of the beam under the same square helix traveling wave tube than equivalent helix (cross section perimeter and the same pitch angle) traveling wave tube has higher gain, but the bandwidth is less than the equivalent helix traveling wave tube, and the rectangular helix in high aspect ratio of the traveling wave tube has the comprehensive advantages of the gain and bandwidth. 4., as the basic theoretical work of interaction between multiple circular helix slow wave structures and strip electron beam, we analyzed the eccentric circular helix slow wave structure loaded by circular waveguide. Based on strict electromagnetic theory analysis, the characteristic equation of the eccentric slow wave system is derived by using the orthogonality of the spiral mode and the addition theorem of the distorted Bessel function. The results show that the single normal helix mode cannot satisfy both the internal and external boundary conditions of the system, and the field solution of the eccentrically slow wave structure is a superposition of multiple mixed modes. The numerical calculation shows that the eccentric distance reduced slow wave structure in the main mode frequency normalized phase velocity and the interaction impedance, the influence of the dispersion and coupling impedance in high frequency by eccentric displacement
【學位授予單位】：電子科技大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TN124

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本文編號：1344603