A novel slotted helix slow-wave structure for high power Ka-band traveling-wave tubes

A novel slotted helix slow-wave structure （SWS） is proposed to develop a high power, wide-bandwidth, and high reliability millimeter-wave traveling-wave tube （TWT）. This novel structure, which has higher heat capacity than a conven- tional helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix tape. In this paper, the electromagnetic characteristics and the beam-wave interaction of this novel structure operating in the Ka-band are investigated. From our calculations, when the designed beam voltage and beam current are set to be 18.45 kV and 0.2 A, respectively, this novel circuit can produce over 700-W average output power in a frequency range from 27.5 GHz to 32.5 GHz, and the corresponding conversion efficiency values vary from 19% to 21.3%, and the maximum output power is 787 W at 30 GHz.

THE COUPLING IMPEDANCE OF VANE-LOADED TAPE HELIX SLOW-WAVE STRUCTURE

Based on the actual vane-loaded tape helix slow wave structure, a new theoretical analytic model for calculating coupling impedance is proposed by Chen Qingyou, et al.(1999)with calculated values of dispersion in good agreement with measured ones. In this paper, it is continued to use this model to calculate the coupling impedance of such a structure, and analyze the effects of the propagation power within vane gaps and the helix gap on the coupling impedance.As a result, the theoretical values are found to be in good agreement with the measured ones,with the maximum difference less than ±18%.

Frequency Tunability and Slow-Wave Characteristics of a High-Efficiency Ridged MILO

A high-efficiency ridged magnetically insulated transmission line oscillator (RMILO) is proposed and investigated theoretically and numerically in this paper. In the RMILO, ridge-disk vanes are introduced to enhance the power efficiency. Theoretical investigation shows that the ridge-disk can enhance the coupling impedance of the slow-wave structure (SWS), and so enhance the power efficiency. Moreover, the ridge has a weak influence on frequency, so, it influences little on the tunability of the MILO. In simulation, when the applied voltage is increased to 807 kV, the RMILO can get the 3 dB tunable frequency range with 7.6 - 13.9 GHz and the 3 dB tuning bandwidth with 58.6% which has an increase of 27.6% compared with the conventional MILO. So, the tuning performance of the RMILO is more superior. Besides, the RMILO gets the maximum output power of 7.1 GW, the corresponding power efficiency is 22.6% and the frequency is 1.400 GHz. Furthermore, when the applied voltage is increased to 807 kV, high-power microwave with a power of 13.5 GW, frequency of 1.400 GHz, and ef?ciency of 24.5% is generated, which has an increase of 20.2% compared with the conventional MILO. The simulation results con?rm the ones predicted by theoretical analysis.

Small-signal analysis of a rectangular helix structure traveling-wave-tube

This paper investigates the properties of traveling wave-beam interaction in a rectangular helix traveling-wave-tube （TWT） for a solid sheet electron beam. The ＂hot＂ dispersion equation is obtained by means of the self-consistent field theory. The small signal analysis,which includes the effects of the beam parameters and slow-wave structure （SWS） parameters,is carried out by theoretical computation. The numerical results show that the bandwidth and the small-signal gain of the rectangular helix TWT increase as the beam current increases;and the beam voltage not obviously influences the small signal gain. Among different rectangular helix structures,the small-signal gain increases as the width of the rectangular helix SWS increases,however,the bandwidth decreases whether structure parameters a and L or ψ and L are fixed or not.In addition,a comparison of the small-signal gain of this structure with a conventional round helix is made.The presented analysis will be useful for the design of the TWT with a rectangular helix circuit.

Investigation of a wideband folded double-ridged waveguide slow-wave system

The folded double-ridged waveguide structure is presented and its properties used for wide-band traveling-wave tube are investigated. Expressions of dispersion characteristics, normalized phase velocity and interaction impedance of this structure are derived and numerically calculated. The calculated results using our theory agree well with those obtained by using the 3D electromagnetic simulation software HFSS. Influences of the ridge-loaded area and broad-wall dimensions on the high frequency characteristics of the novel slow-wave structure are discussed. It is shown that the folded double-ridged waveguide structure has a much wider relative passband than the folded waveguide slow-wave structure and a relative passband of 67% could be obtained, indicating that this structure can operate in broad-band frequency ranges of beam-wave interaction. The small signal gain property is investigated for ensuring the improvement of bandwidth. Meanwhile, with comparable dispersion characteristics, the transverse section dimension of this novel structure is much smaller than that of conventional one, which indicates an available way to reduce the weight of traveling-wave tube.

400 km/h高铁隧道出入口缓解微气压波综合效果分析

为准确预测高速铁路隧道出口微气压波幅值,以三维、非定常、可压缩流动理论为基础,利用Fluent软件模拟时速400 km的列车驶入100 m2端墙式双线隧道时,分析列车在不同入口侧部开口缓冲结构、出口侧部开口缓冲结构及出口仰坡斜率下对出口微气压波的影响效应,并结合出入口缓冲结构综合分析微气压波联合缓解效果。结果表明:1)对出口微气压波峰值、出口缓冲结构、仰坡斜率进行相关性分析,结合辐射立体角公式线性拟合立体角变化趋势,得出立体角随缓冲结构开口率、洞门仰坡斜率的增大均呈现由急到缓的2段式上升曲线;2)数值分析得到在不同入口缓冲结构开口率下初始压缩波压力梯度变化规律和出口微气压波缓解效率规律,再结合隧道出口缓冲结构、仰坡斜率提出微气压波联合缓解效率预测公式,预测分析微气压波联合缓解效果在不同影响因素下的变化趋势;3)针对预测结果结合数值模拟验证工况进行误差分析,表明可以将出口立体角分析结果与入口缓冲结构缓解规律相结合。

High efficiency X-band relativistic backward wave oscillator with non-uniform slow wave structures

Backward wave oscillators （BWOs） driven by intense relativistic electron beams are very efficient means of producing high-power microwaves. However, the efficiency of conventional BWO is lower than 30%. An X-band oversized BWO with non-uniform slow wave structure is designed to improve RF output characteristics. In particle-in-cell simulation, a high power microwave with a power of 8.0 GW and efficiency of 40% is obtained, compared with that of 30% obtained in a conventional relativistic BWO.

一种束半径可调的环形强流电子束产生技术及应用

束半径可调的强流环形电子束在跨波段跳频高功率微波产生器件中有重要应用。提出了一种改变外加引导磁场位形从而改变环形强流电子束半径的技术。该技术的核心部件由环形阴极、阳极、电子束转移通道、电子束传输通道和三段螺线管组成。当三段螺线管的通流的电流大小不一样时,该螺线管系统就能产生不同位形的磁场。在粒子模拟中,当三段螺线管的通流电流大小分别为1025 A、107 A、107 A和300 A、300 A、0 A时,螺线管产生两种不同位形的磁场,实现电子束半径的改变。从单粒子运动理论出发,本文推导出电子束在梯度磁场引导下的运动轨迹表达式,解释了电子束半径在梯度磁场下变化的原理,还研究了梯度磁场的斜率和极差对电子束轨迹的影响。在跨波段器件仿真中,X波段输出功率为1.6 GW,频率为8.2 GHz,效率为40%;Ku波段输出功率为1.5 GW,频率为14.4 GHz,效率为38%。

基于T形四周期谐振慢波结构的X波段高功率微波产生技术的理论与仿真

优化设计了T形四周期谐振慢波结构,并进行了高频理论分析.利用镜像法将T形波导单元进行脊波导化等效设计,并通过等效电路分析了等效脊波导的高频特性,由此进行T形波导的谐振频率与结构解析理论分析.在此基础上构造了T形四周期谐振慢波结构,对该结构进行色散特性分析,确定谐振模式和频率,得到了模式同步电压范围.最后基于提出的T形周期谐振慢波结构进行对应的相对论扩展互作用辐射源的仿真验证.通过三维粒子仿真模拟分析及优化设计,在448 kV注电压、400 A注电流和0.4 T的均匀轴向磁场条件下,得到了频率为9.8 GHz、平均输出功率71.4 MW的高功率微波,对应电子效率为39.8%.本文提出的以T形波导为单元的新型谐振慢波结构有效地利用较少周期实现高效率、高功率微波产生,为高功率微波科学提供了有效的高频结构的紧凑化方案.

高效率K波段200W行波管研制

通过对高效率慢波系统和多级降压收集极的仿真模拟计算,设计了一支在效率、功率和带宽方面具有综合优势的K波段螺旋线行波管。研制出的行波管实际测试结果表明,在19~25 GHz范围内,连续波饱和输出功率大于200 W,整管效率大于50%,阴极工作电压9.8 kV。

Q波段宽带螺旋线行波管研制

针对当前武器装备小型化、多功能特点,研发了一支多用途Q波段螺旋线行波管。该管采用聚焦极电子枪、螺旋线慢波线、PPM聚焦系统和三级降压收集极。适当调节阴极和阳极工作电压可实现Q波段宽频带功率输出,对多用途雷达、电磁兼容、通信装备一体化设计具有重要意义。样管性能:在频率33~39 GHz,占空比70%,峰值功率大于260 W,总效率超过47%,可作为毫米波雷达源,用于地貌绘制和恶劣天气云层厚度探测;在频带40~50 GHz提供最小170 W的连续波输出功率,总效率超过39%,既能拓展电磁兼容实验室频谱,还可应用于高速移动车辆、无人机,通过移动卫星上传视频、图像数据等。

一种宽带瓦量级交错双栅脊波导返波振荡器的研究

为满足太赫兹领域对大功率、宽带宽的太赫兹辐射源的需求,提出了一种新型交错双栅脊波导(RDSG)慢波结构。设计并优化了交错双栅脊波导返波振荡器的高频结构,同时对交错双栅脊波导和常规交错双栅的高频特性进行了仿真和对比,结果表明:当二者相速度接近时,交错双栅脊波导拥有更宽的“冷”通带带宽和更高的耦合阻抗。PIC仿真结果表明,在1 THz频段,交错双栅脊波导返波振荡器拥有超过175 GHz的可调谐带宽以及1.1 W的输出功率,比相同工作条件下的常规交错双栅结构输出功率了提高34%~42%。

螺旋线行波管慢波结构散热性能的发展现状

行波管是一种具有宽频带的微波管,它自发明以来已有60多年的历史,至今仍广泛应用于通信、雷达系统和电子对抗。随着卫星通信技术的快速发展,对高性能的大功率行波管的需求越来越迫切,而大功率伴随着更高的热损耗,因此,对其散热性能的研究是一项重要的工作。国内外专家学者对此做了大量的研究,本文综合叙述了目前行波管慢波组件材料和结构、组装方式以及接触热阻的研究现状,并总结了一些散热性能的评价方法。

平面超材料对曲折线慢波结构行波管效率改善和杂模抑制的影响

针对U型曲折线慢波结构带状注行波管杂模抑制和互作用效率提高等面临的挑战,提出了一种开口菱形超材料结构。在综合考虑电路单元谐振性能、与U型曲折线慢波结构之间的协调配合以及电路实现可行性和结构简单等因素,通过电路设计和数值模拟优化等具体措施相结合,探讨这种超材料对增强注波互作用表面电场和抑制电路振荡的效果。在Ka波段优化的结果表明,这种超材料在抑制杂波和改善注波互作用效率方面效果明显,对此类行波管稳定性提高具有重要意义。

不同方法制备的螺旋线慢波组件的散热性能的研究

利用电阻温度系数法对几种方法制备的慢波组件散热性能进行了实验研究,结果表明石墨热挤压法、磁控溅射覆膜法及压力扩散焊接法和无变形热挤压法比冷弹压法和传统的缠钼带热挤压法制备的慢波组件散热性能强许多.传统的石墨热挤压法可与无变形热挤压法制备的组件的散热能力相比拟,但石墨热挤压法会引起慢波组件的两次变形,使慢波组件的微波反射点增多增强.压力扩散焊接法制备的慢波组件散热性能比溅射镀膜法制备的慢波组件散热性能稍强,但压力扩散焊接法与溅射镀膜法相比具有更低的微波损耗.这些结果为制备散热性能强的慢波组件提供了有益的实验结果.

螺旋线行波管慢波组件散热性能的研究进展

螺旋线行波管具有宽频带、高增益和高功率等优点,当今被大量应用于卫星通信系统、电子对抗系统和雷达系统。慢波组件是螺旋线行波管的关键组成部分,它的性能优劣直接决定着整管水平。慢波组件的散热性能不仅是决定行波管平均输出功率的主要因素,也是直接影响行波管工作稳定性与可靠性的重要因素。本文针对螺旋线行波管慢波组件,总结了螺旋线慢波组件散热性能的实验测试方法和理论分析方法,分析了影响散热性能的各种因素和各种改善方法。分析比较了不同材料的螺旋线、管壳和夹持杆,不同结构的夹持杆和管壳,不同组件装配方法对慢波组件散热性能的影响。介绍了将金刚石和纳米材料等新型材料应用于螺旋线慢波组件的研究进展。

同轴慢波结构相对论高功率微波产生器初步实验研究

对一种同轴慢波结构相对论高功率微波产生器进行了初步的实验研究。利用数值模拟优化得到的结构,建立了实验装置。初步实验结果表明:该种器件具有微波产生效率高的优点,在实验系统并没有达到优化状态的情况下得到的微波转换效率达28%,峰值功率约为1.3 GW。微波频率基本不随二极管电压变化,约为7.7 GHz,这与文献中数值模拟给出的结果一致。

螺旋线行波管慢波组件散热性能的研究

提出了慢波组件散热性能的评价方法——电阻温度系数法,利用此方法对冷弹压法、缠钼带热挤压法、石墨热挤压法及新型的无变形热挤压法制备的慢波组件散热性能进行了实验研究,结果表明无变形热挤压方法比冷弹压法和传统的缠钼带热挤压法制备的慢波组件散热性能好。传统的石墨热挤压法可与无变形热挤压法制备的组件的散热能力相比拟,但石墨热挤压法会引起慢波组件的两次变形,使慢波组件的微波反射点增多增强,从而影响慢波组件的电性能。对国产BeO和进口BN夹持杆组成的慢波组件的散热性能进行了比较研究。同时对镀铜和镀金螺旋线与无镀层螺旋线组成的慢波组件也进行了对比研究。这些结果为制备散热性能好的慢波组件提供了有益的实验结果。

矩形螺旋线慢波电路高频特性的数值分析

介绍了用ANSOFT公司提供的HFSS 10.0软件模拟计算色散特性和耦合阻抗的理论方法,并对矩形螺旋线慢波结构的高频特性进行了数值模拟。结果表明:和传统的圆螺旋线结构相比,矩形结构具有更高的耦合阻抗,能有效减小器件体积;在横截面厚度和螺旋角一定的情况下,当矩形螺旋线的宽高比大于4时,相速几乎不变,但是耦合阻抗随着宽度的增加而下降;同时螺旋角的减小可以降低系统的相速,减小工作电压。由于可利用微电子机械系统(MEMS)印制技术制作,具有可与带状电子束作用,提高效率等优点,矩形螺旋线在紧凑型行波管(TWT)领域有广阔的应用前景。