高功率速调管聚焦磁场设计研究

 国产45 MW速调管是在原国产30 MW HK-1型速调管的基础上改进和发展起来的，其聚焦磁场设计也是参照30 MW速调管聚焦磁场设计并在其基础上加工改造完成。为此必须对旧聚焦系统进行改造，设计出符合需要的磁场分布，以满足45 MW速调管工作的需要。首先从理论上找出速调管工作时的理想磁场值，根据该磁场分布设计出相应的线圈结构；其次根据45 MW速调管的结构尺寸，对30 MW速调管的线圈支架进行改造，利用旧线圈和新支架组成新的聚焦系统；最后，根据理论模拟和测试结果，调整和优化各组线圈的电流值，给出速调管工作时的各组聚焦电源运行参考值。叙述了新聚焦线圈的理论设计和测试分析，包括新线圈支架的设计、水冷系统与线圈的结构安排和整体的测试结果，最后根据速调管高功率测试运行状态给出速调管工作时的聚焦线圈电流的参考值。     

450kV高功率速调管调制器系统

研制了一套用于新型速调管测试的450 kV高功率调制器系统。根据系统指标分别设计了脉冲变压器、脉冲形成网络以及充电电路等主要部件。同时,针对高功率脉冲开关的要求,对闸流管相关性能进行了比较研究,并对其触发、保护电路作了优化设计。并利用可编程控制器与触摸屏组合方式实现了调制器和速调管的控制与连锁保护。利用电力电子仿真软件Saber对调制器主电路进行了建模与仿真,脉冲电压波形仿真结果与在水负载上进行的满功率试验结果一致:脉冲宽度2.5μs,脉冲前沿1.1μs,脉冲后沿1.7μs。调制器输出脉冲电压450 kV,脉冲电流600 A,满足速调管测试需要。     

S波段长脉冲相对论速调管放大器中杂模振荡导致的脉冲缩短抑制研究

研究了相对论速调管放大器中的脉冲缩短问题.分析表明杂模振荡是引起脉冲缩短的重要原因.利用粒子模拟对振荡的模式进行了分析,研究了振荡的机理,在粒子模拟中利用吸收介质对杂模实现了有效的抑制.最后,在实验中解决了相对论速调管放大器中的脉冲缩短问题,在输出微波峰值功率约为920 MW时将脉宽由77 ns提高到137 ns.     

相对论返波管驱动的两腔大间隙速调管放大器

在大型功率合成阵列中,为解决现有种子源输出功率不足的问题,提出了利用相对论返波振荡器作为种子源锁定大间隙速调管放大器频率和相位的思路,并进行了由一个相对论返波管驱动一个高功率注入两腔大间隙速调管放大器的理论和初步实验研究。实验结果表明:大间隙速调管的频率被相对论返波管锁定,两个微波源的实时相位差在单脉冲内锁定在16之内,多脉冲间的相对相位差锁定在11之内,锁相时间约40 ns;在注入功率约22 MW时,大间隙速调管的输出功率约230 MW,增益约10 dB。     

紧凑型矩形波导内功率合成器设计

介绍了一种基于常规速调管功率合成和脉冲压缩的微波源系统,为实现多路高峰值功率速调管的功率合成,设计了一种紧凑型、近平面结构的微波功率合成器。在2.856 GHz频点处,合成器各端口反射损耗和相对端口隔离度均大于45 dB。当两路峰值功率为50 MW的微波功率合成时,合成器内的最大场强约为9.6 MV/m,合成效率大于99%。在四端口功率合成器的基础上,通过两级合成可实现一种八端口微波功率合成器,当四路峰值功率50 MW的微波功率合成时,合成器内最大场强约为13.5 MV/m。     

X波段长脉冲同轴多注相对论速调管放大器的分析与设计

为了提高相对论速调管放大器的工作频率、输出功率以及转换效率, 结合三重轴相对论速调管和多注速调管的特点, 采用三维电磁粒子模拟软件分析与设计了工作在X波段的长脉冲同轴多注相对论速调管放大器, 通过优化设计有效地抑制了X波段长脉冲相对论速调管放大器的自激振荡, 避免了脉冲缩短现象的产生, 使X波段相对论速调管放大器在长脉冲状态下能够稳定工作, 在注入微波功率为70 kW、束压为600 kV、束流为5 kA、轴向引导磁感应强度为0.8 T的条件下, 输出微波功率达到了1.23 GW, 效率为41%, 增益为42 dB.     

常规速调管空间功率合成微波源

基于常规速调管,研制了用于开展空间功率合成实验的微波源系统。介绍了50 MW超大功率速调管发射机的系统组成、大功率速调管、相位控制及高功率测试系统等。重点阐述了超大功率速调管发射机的关键技术,并针对超大功率发射机的设计难点提出了具体的解决方案。为提高超大功率发射机的可靠性,设计了基于绝缘栅双极晶体管（IGBT）的感应叠加型全固态调制器。给出了超大功率发射机的测试结果,并探讨了超大功率速调管发射机的改进方法。最后对基于常规速调管,研制用于空间功率合成微波源系统的发展进行了展望。     

L波段高功率多注速调管设计与模拟

 开展了峰值功率10 MW、平均功率150kW的L波段多注速调管的研究工作。采用均匀场多透镜聚焦系统对多电子注进行聚焦,获得了具有良好层流性和波动性的旁轴多注电子光学系统;采用二次谐波腔,对6个电子注、6个同轴谐振腔结构的速调管进行了注波互作用计算。结果表明,当电子注电压为115 kV,电流为132 A时,可获得大于10 MW的脉冲输出功率,大于65%的输出效率和大于45 dB的增益。     

反转永磁聚焦C波段高功率多注速调管

反转永磁聚焦C波段高功率多注速调管作为加速器系统的功率源，具有脉冲输出功率高、平均功率大、寿命长的优势，在工业辐照、放射治疗、无损检测等领域具有广阔的应用前景。设计并研发了一种可用于加速器系统的反转永磁聚焦C波段高功率多注速调管。其电子光学系统采用多电子注、周期反转永磁聚焦技术，高频系统工作在TM₂₂₀高次模式、多腔参差调谐，散热采用水冷方式。通过计算确定了结构参数，研制出速调管样管，通过测试，获得了大于3 MW的峰值输出功率，和计算结果相吻合。     

长脉冲X波段多注相对论速调管放大器的初步实验研究

设计了工作在长脉冲的X波段同轴强流多注相对论速调管放大器, 对长脉冲强流多注电子束在多注器件结构中的传输、电子束经过输入腔和中间腔后的束流调制以及经过输出腔的微波提取等过程进行了实验研究, 采用了相应的设计措施以减轻实验中出现的脉冲缩短现象, 得到了初步的长脉冲实验结果. 在输入微波功率60 kW、频率9.378 GHz、电子束电压700 kV、束流4.2 kA、轴向引导磁感应强度1 T的条件下, 重频5Hz输出微波功率为670 MW, 脉宽89 ns, 效率为23%, 增益为40 dB, 输出微波频率与输入微波一致. 从实验上验证了几十千瓦级输入微波驱动X波段同轴多注RKA输出几百兆瓦长脉冲高功率微波的可行性, 为后续更高功率研究打下了基础.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.