發(fā)布時間：2018-09-05 20:27

【摘要】：相對論速調(diào)管放大器(Relativistic Klystron Amplifier,RKA)是一種輸出功率在吉瓦(GigaWatt,GW)量級的微波器件,其電子束產(chǎn)生、束波互作用、微波提取、電子束收集是在不同區(qū)域中完成的,具有高功率、高增益、高效率、幅度和相位穩(wěn)定的特點,廣泛應用于通信、雷達、微波武器等領域,具有極大的軍用和民用前景。目前國內(nèi)設計的RKA的微波提取效率還比較低,為獲得較高的輸出功率,通常是給陰極提供很大的發(fā)射電壓和電流,這需要性能更高的加速器。因此,設計出微波提取效率更高的RKA不僅能夠提高輸出功率,而且有利于減小系統(tǒng)體積和重量。輸出腔對于RKA的效率有重要影響。輸出腔提取效率的高低,直接影響整管的效率。本論文主要研究了S波段的RKA輸出腔,推導了輸出腔的電子效率計算式,設計了雙間隙輸出腔和單間隙輸出腔模型,計算了高頻特性和粒子模擬。最后設計了二次提取腔,并進行了粒子模擬仿真。本論文的主要研究內(nèi)容如下:首先分析了輸出腔的等效電路模型。以一維電子圓盤模型大信號理論為基礎,推導了輸出腔束波轉換效率關系式,重點分析了單間隙輸出腔和雙間隙輸出腔的電子效率表達式,并分析了多個變量對電子效率的影響。利用常規(guī)大功率速調(diào)管放大器的設計思路,分析了RKA輸出腔主要性能指標及參數(shù)選取,包括直流電子束參數(shù)、電子束聚焦參量、諧振腔的參數(shù)等。研究了雙間隙和單間隙輸出腔的封閉腔高頻特性,分別計算了本征模諧振頻率及場分布,之后對封閉腔開了耦合孔,設計出了雙間隙輸出腔、單間隙輸出腔的開放腔,計算了它們諧振頻率、場分布、有載Q值(LQ)及特性阻抗R/Q等參數(shù)。利用粒子模擬程序,對雙間隙輸出腔的封閉腔和開放腔分別進行了模擬,觀察了一些高頻特性及微波提取情況,分析了雙間隙提取腔對電子束提取后電子束剩余能量的分布。根據(jù)電子束剩余的能量確定了電壓值并利用此電壓作為重要參量設計了單間隙輸出腔,分析了其冷腔及熱腔特性。最后設計了一種二次提取腔,并對此結構進行了PIC模擬和優(yōu)化。模擬結果表明,利用電壓和電流分別為900keV、7.5kA的電子束,電流調(diào)制深度100%,外加1.2T的軸向引導磁場,模擬得到微波功率3.5GW,其中,初級提取腔輸出功率值為2.5GW,次級提取腔輸出功率值為1.0GW,總的提取效率約52%。
[Abstract]:Relativistic klystron amplifier (Relativistic Klystron Amplifier,RKA) is a kind of microwave device whose output power is in the order of GigaWatt,GW. Its electron beam generation, beam wave interaction, microwave extraction, and electron beam collection are completed in different regions, with high power and high gain. High efficiency, stable amplitude and phase, widely used in communications, radar, microwave weapons and other fields, has a great military and civil prospects. At present, the microwave extraction efficiency of RKA designed in China is still low. In order to obtain higher output power, the cathode is usually provided with large emission voltage and current, which requires a higher performance accelerator. Therefore, the RKA with higher microwave extraction efficiency can not only increase the output power, but also reduce the volume and weight of the system. The output cavity has an important effect on the efficiency of RKA. The extraction efficiency of the output cavity directly affects the efficiency of the whole tube. In this paper, the RKA output cavity in S-band is studied, the electronic efficiency of the output cavity is deduced, the two-gap output cavity and the single-gap output cavity model are designed, the high frequency characteristic and particle simulation are calculated. At last, the second extraction cavity is designed, and the particle simulation is carried out. The main contents of this thesis are as follows: firstly, the equivalent circuit model of output cavity is analyzed. Based on the large signal theory of one-dimensional electronic disk model, the expression of beam conversion efficiency of output cavity is derived, and the expressions of electronic efficiency of single-gap output cavity and double-gap output cavity are analyzed. The influence of several variables on the electron efficiency is analyzed. Based on the design idea of conventional high power klystron amplifier, the main performance indexes and parameters selection of RKA output cavity are analyzed, including DC electron beam parameters, electron beam focusing parameters, resonant cavity parameters, etc. The high frequency characteristics of the closed cavity with two gaps and one gap are studied. The intrinsic mode resonance frequency and the field distribution are calculated respectively. After that, the coupling holes are opened to the closed cavity, and the open cavity with double gap output cavity and single gap output cavity is designed. The resonant frequency, field distribution, loaded Q value (LQ) and characteristic impedance R / Q are calculated. By using particle simulation program, the closed cavity and open cavity of double-gap output cavity were simulated, and some high frequency characteristics and microwave extraction were observed, and the distribution of residual energy of electron beam after extraction of electron beam in two-gap cavity was analyzed. Based on the residual energy of the electron beam, the voltage value is determined and the single gap output cavity is designed by using the voltage as an important parameter. The characteristics of the cold cavity and the thermal cavity are analyzed. Finally, a secondary extraction cavity is designed, and the structure is simulated and optimized by PIC. The simulation results show that the microwave power of 3.5 GW can be obtained by using the electron beam with a voltage and current of 900keV and 7.5kA respectively, the current modulation depth is 100, and the axial guiding magnetic field of 1.2 T is applied to simulate the microwave power. The output power of primary extraction cavity and secondary extraction cavity is 2.5 GW and 1.0 GW respectively, and the total extraction efficiency is about 522GW.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN122

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