Development and testing of a high-power S-band klystron at BINP SB RAS

This paper details the development and testing of the first working prototype of the S-band high-power klystron,accomplished at the Budker Institute of Nuclear Physics,Siberian Branch,Russian Academy of Sciences(BINP SB RAS).Upon testing,the klystron demonstrated the following parameters:an operating frequency of 2856 MHz and a peak power output of 50 MW.The paper presents the klystron's design,its constituent units,and pertinent processing procedures,along with discussions on the measurement of its parameters.

Quantitative investigation of multi-fracture morphology during TPDF through true tri-axial fracturing experiments and CT scanning

Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.

Hydrologically induced orientation variations of a tri-axial Earth's principal axes based on satellite-gravimetric and hydrological models

The Earth is a tri-axial body, with unequal principal inertia moments, A, B and C. The corresponding principal axes a, b and c are determined by the mass distribution of the Earth, and their orientations vary with the mass redistribution. In this study, the hydrologically induced variations are estimated on the basis of satellite gravimetric data, including those from satellite laser ranging （SLR） and gravity recovery and climate experiment （GRACE）, and hydrological models from global land data assimilation system （GLDAS）. The longitude variations of a and b are mainly related to the variations of the spherical harmonic coefficients C 22 and S 22, which have been estimated to be consisting annual variations of about 1.6 arc seconds and 1.8 arc seconds, respectively, from gravity data. This result is confirmed by land surface water storage provided by the GLDAS model. If the atmospheric and oceanic signals are removed from the spherical harmonic coefficients C 21 and S 21, the agreement of the orientation series for c becomes poor, possibly due to the inaccurate background models used in pre-processing of the satellite gravimetric data. Determination of the orientation variations may provide a better understanding of various phenomena in the study of the rotation of a tri-axial Earth.

Determination of Direction of Arrival of Seismic Wave by a Single Tri-axial Fiber Optic Geophone

A fiber Bragg grating (FBG) geophone and a surface seismic wave-based algorithm for detecting the direction of arrival (DOA) are described. The operational principle of FBG geophone is introduced and illustrated with systematic experimental data, demonstrating an improved FBG geophone with many advantages over the conventional geophones. An innovative, robust, and simple algorithm is developed for obtaining the bearing information on the seismic events, such as people walking, or vehicles moving. Such DOA estimate is based on the interactions and projections of surface-propagating seismic waves generated by the moving personnel or vehicles with a single tri-axial seismic sensor based on FBGs. Of particular interest is the case when the distance between the source of the seismic wave and the detector is less than or comparable to one wavelength (less than 100 m), corresponding to near-field detection, where an effective method of DOA finding lacks.

应用型电子直线加速器用C波段大功率速调管研究与开发

为满足C波段应用型直线加速器功率源要求,研制了一支C波段大功率速调管。通过对电子枪结构模拟计算并利用正反向组合式聚焦线圈调整过渡区磁场,完成了电子光学系统设计,电子注通过率达到100%,电子注波动率为4.8%。综合应用一维至三维计算程序对注-波互作用段开展参数优化及PIC仿真,最终确定了6个谐振腔的速调管方案。腔体加工冷测调配后焊接形成整管,并开展了高功率测试,在电子注电压为115 kV、电流为79.6 A条件下,馈入频率为5712 MHz、功率为100 W的信号时,该速调管可输出的峰值功率为3.52 MW,增益为45.5 dB,效率为38.5%,达到了预期研制目标。

TH2103A型速调管阳极电流测量和保护系统

[目的]工作频率3.7 GHz的TH2103A型高功率速调管广泛应用在托卡马克实验装置中。为了简化高压供电系统(去掉阳极调制中的电真空四极管),在HL-2A装置的TH2103A型速调管中引入了一种基于分压模式的供电方式。为了保证速调管在该供电模式下安全运行,研制了阳极电流的测量和保护系统。[方法]对该供电模式下的阳极电流特点进行了分析:阳极电流会出现正常、正向过流或反向过流的情况。当阳极电流出现正向过流或反向过流时,代表有大量的电子轰击阳极或大量电子从阳极流出,这些现象对速调管来说都是非常危险的,通常会引起速调管钛泵过流,甚至损坏速调管。因此对阳极电流进行准确的测量以及当阳极电流出现过流时切断高压对速调管进行保护非常重要。文章介绍了阳极电流测量系统的原理和供电模式,阳极保护系统的原理和实施方案,在实验过程中对阳极电流的测量和保护系统的可靠性进行了验证。[结果]证明了该供电模式下阳极电流测量和保护系统的有效性和可靠性。[结论]文章所述供电模式和阳极测量保护系统对基于TH2103A型速调管的运行和维护具有重要参考意义。

一种基于嵌套结构的锁频锁相高功率微波振荡器仿真研究

高功率微波(HPM)产生器件通过增加慢波结构的过模比使得功率容量显著提高。嵌套型结构让过模器件的空心结构或内导体结构得到使用,同时嵌套型器件的低阻抗使得其与低阻脉冲功率源能良好匹配。基于内外嵌套结构提出了一种锁频锁相高功率微波振荡器。相对于传统的锁频锁相方法,提出了基于耦合波导实现锁频锁相的新方法。内外相对论速调管振荡器(RKO)产生的微波信号通过耦合波导泄漏到高频结构中,对电子束进行预调制,从而实现锁频锁相。另外,为实现内外高功率微波通道合成,设计了双通道功率合成器。在振荡器的工作频点,功率合成器能弥补振荡器两输出通道相位差,使得功率合成效率提高,合成效率为98.3%。在二极管电压575 kV,磁场强度0.6 T条件下,内外RKO的微波输出功率分别为2.2 GW和3.2 GW,频率差波动小于20 MHz,相位差稳定在10°附近;加载双通道功率合成器,仿真结果表明,微波输出功率为5.31 GW,功率效率32.2%。结果表明,嵌套器件在互锁状态时,振荡器饱和时间缩短,输出功率增大。

速调管放大器输入腔的匹配理论和模拟研究

基于输入微波与腔体耦合的等效电路模型,对于任意的腔体和电子束参数,建立了任意的输入微波与腔体耦合的速调管放大器输入腔的两种匹配状态的理论。建立了带有互感和电子束等效电阻和电容等参数的输入腔等效电路模型,推导了入射功率与反射功率的表达式,以及输入微波与带有电子束的输入腔耦合的完全匹配状态和任意的耦合这两种情形时输入功率和间隙电压关系的公式。推导了完全匹配状态时输入微波工作频率与输入腔有载品质因数的表达式。推导了复耦合系数等于1时输入腔外观品质因数与热腔品质因数的表达式,得出了当工作频率等于输入腔谐振频率,输入腔外观品质因数与热腔品质因数相等,且满足电子束等效电容远小于1时接近达到匹配状态,与传统理论基本一致。通过对比两种状态时的入射功率,得出了匹配状态时的入射功率小于复耦合系数等于1时入射功率的结论。通过对比复耦合系数等于1时新理论和传统理论的入射功率,得出不考虑电子束等效电容情况下两者相等的结论。采用二维粒子模拟的模型与匹配理论进行了对比,粒子模拟与理论基本一致。根据匹配理论找到了接近匹配状态的工作频率与有载品质因数以及较小的输入功率。

高功率高效率速调管输出耦合器的优化与设计

输出耦合器作为速调管关键部件,其性能直接关系到速调管的整体表现。然而,耦合器故障却是速调管及多种真空电子设备中最为常见的问题之一,特别是在高连续波功率运行场景下,这一问题更为突出。针对连续波650 MHz/800 kW高效率速调管,对输出耦合器进行优化设计,并在单注和多注速调管耦合器测试方面取得了重要突破:单注速调管输出耦合器在连续波模式下的测试功率已达到690 kW以上,为了进一步增加功率容量,采用T-bar结构过渡,并对耦合器进行优化设计,使陶瓷附近电场分布更均匀;而多注速调管矩形波导窗输出耦合器最高测试功率达到全驻波115 kW。此外,通过对耦合器的结构、材料以及散热方式进行分析与优化,积极探索提升耦合器功率容量的多种可能途径,进一步增强了速调管的稳定性和可靠性。

C波段50mW多注速调管高频系统的设计

本文提出一种全新的、应用于C波段50 mW高功率多注速调管输出系统。该系统首次采用TM 310高次模式多注结构,将整管工作电压由单注的354 kV大幅降低至250 kV,整管长度由单注的1.4 m缩短至0.9 m;并创新性地采用矩形TM 310结构,结合输出波导补偿结构,有效地解决了圆形TM 310结构外品质数不足的问题,保证了整管的输出稳定性。本文提出的C波段50 mW多注速调管能大幅降低整管工作电压、减小体积,可大幅提高系统的可靠性及机动性。本文研究的新型结构C波段50 mW多注速调管高频系统有效解决了高次模式高功率稳定输出的问题,降低了输出结构的设计复杂性、减小了传输系统体积并降低了成本,对未来多注高峰值功率产品的设计具有非常重要的意义。

工业应用的S波段小型化连续波速调管的设计

速调管具有大功率、高效率、长寿命的特点和优势,在大科学和工业加热中有着广泛的应用。针对微波等离子体化学气相沉积(MPCVD)应用设计了一种10~15 kW级的小型化连续波速调管,速调管总重量小于30 kg,在电压16 kV、电子注电流2 A的状态下获得了大于17 kW的输出功率,效率达到56%以上。

一种抑制栅控多注速调管雷达发射机射频泄漏的方法

针对某型C波段栅控多注速调管雷达发射机在无激励信号条件下的射频泄漏问题,研究分析了问题原因,提出抑制多注速调管自激振荡和减少微波泄漏的改进方法,优化发射机调制脉冲和激励信号加入时机的技术方案,并研制了相关硬件。测试表明,改进后原雷达发射机射频泄漏得到有效抑制,有效降低了射频泄漏对雷达自身产生的不利影响。改进方法和结果对于同类型雷达发射机具有借鉴意义。

高Q值单间隙同轴谐振腔的物理设计与实验研究

随着高功率微波源向高功率、高频率和长脉冲方向不断发展,同轴相对论速调管放大器(RKA)成为近年来研究热点之一,然而其发展一直受限于自激振荡等问题存在,为此,设计一种高Q值单间隙同轴谐振腔,以抑制同轴RKA中TEM模式泄露引起的自激振荡。通过对单间隙同轴谐振腔TM_(01)模式与TEM模式转化进行理论分析与仿真模拟,发现同轴谐振腔上下槽深差值与轴向错位值对其Q值变化影响很大,当上下槽深差值与轴向错位值分别为0.3 mm和0 mm时,同轴谐振腔的Q值为极大值(18764),意味着此时谐振腔中两种模式转化最小,多组谐振腔级联后自激振荡风险大大降低。将三组级联的高Q值单间隙同轴谐振腔应用于紧凑型同轴RKA,粒子模拟和实验结果表明,器件的输出微波功率稳定,频谱纯净,无自激振荡等问题存在。

速调管高功放固态化改造技术方案设计

高功放是地球站播出系统关键传输设备,目前,广东卫星地球站速调管高功放使用时间长,逐渐老化,存在播出隐患,因此提出速调管高功放固态化改造需求。从速调管高功放和固态高功放的各方面进行比较,阐明固态高功放的优点,通过计算确定固态高功放的功率需求,根据广东卫星地球站的客观情况,制定速调管高功放固态化改造技术方案。

CINRAD/SB聚焦线圈与速调管故障诊断、定位与排除实例

为了解决聚焦线圈故障隐蔽、速调管故障诊断复杂的问题,文章在分析速调管、聚焦线圈设计原理的基础上结合CINRAD/SB新一代天气雷达速调管及聚焦线圈组成框图,通过分析关键部件及关键点的指标参数及波形、实测参数及波形,调整关键部件及关键点参数、波形来判断速调管及其外围组件情况,成功分析、定位及排除了CINRAD/SB雷达速调管及聚焦线圈造成的系统高压不准及无回波故障。

Design and development of radio frequency output window for circular electron–positron collider klystron

This paper presents the first phase of design, analysis, and simulation for the klystron coaxial radio frequency（RF）output window. This study is motivated by 800 kW continuous wave（CW）, 650 MHz klystrons for the future plan of circular electron–positron collider（CEPC） project. The RF window which is used in the klystron output section has a function to separate the klystron from the inner vacuum side to the outside, and high RF power propagates through the window with small power dissipation. Therefore, the window is a key component for the high power klystron. However, it is vulnerable to the high thermal stress and multipacting, so this paper presents the window design and analysis for these problems. The microwave design has been performed by using the computer simulation technology（CST） microwave studio and the return loss of the window has been established to be less than-90 d B. The multipacting simulation of the window has been carried out using MultiPac and CST particles studio. Through the multipacting analysis, it is shown that with thin coating of TiN, the multipacting effect has been suppressed effectively on the ceramic surface. The thermal analysis is carried out using ANSYS code and the temperature of alumina ceramic is lower than 310 K with water cooling.The design result successfully meets the requirement of the CEPC 650 MHz klystron. The manufacturing and high power test plan are also described in this paper.

Design and high-power test of 800-kW UHF klystron for CEPC

To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.

DEVELOPMENT OF 50MW S-BAND KLYSTRON

This letter reports the development of a 50MW S-band klystron in the Institute of Electronics, Chinese Academy of Sciences （IECAS）. It adopted a structure of six-cavity and single output window. Under conditions of an RF （Radio Frequency） pulse width of 4t, ts, a beam voltage of 305,9kV and a beam current of 368A, the peak output power has achieved 51.4MW with an efficiency of 45.6% and a gain of 54dB.

Reconstruction of -35 kV/200 kW HVPS for Test of Klystron Units in LHCD System

The paper introduces the -35 kV/200 kW high voltage power supply (HVPS) which is specially used to test klystron units in LHCD system. The new klystrons must be tested under high voltage level before operation and the old klystrons which have worked for a longtime must be exercised by HVPS in lower hybrid current drive (LHCD) system. As the former HVPS has some shortages in engineering design and operation design, the HVPS has to be modified and rebuilt by adopting new method and technology to solve existing bottle-neck problems.

METHODS FOR IMPROVING EQUIDRIVING POWER-FREQUENCY CHARACTERISTICS OF BROADBAND HIGH POWER KLYSTRON

Two methods for improving the equidriving power-frequency characteristics of broad-band high power klystrons are presented. One is that a comb-line bandpass filter with someattenuation properties is inserted between the TWT driver and the klystron for compensatingthe gain-frequency characteristics of the klystron to get the required equidriving power-frequencycharacteristics. The other is that a reactive element is connected with the input cavity to changeits resonance frequencies f0 and QL, and thus to improve the power-frequency characteristics ofthe klystron.