中物院高功率THz FEL装置的理论分析和优化设计

在1~3 THz频段内设计了11个分点频率,对每一频率的对应的场强和电子束能量进行了选取和计算。模拟结果表明:采用目前参数基本能够达到设计要求;辐射频段在2.6 THz附近时装置输出功率和增益都比较高,可以先锁定这个频段附近进行实验的调试;在长波段即1 THz左右时,滑移效应显著,腔增益和输出功率较低,实验实现比较困难,因此在1 THz频段附近必须积极想办法来提高输出功率。     

中物院高功率THz FEL装置的理论分析和优化设计

在1~3 THz频段内设计了11个分点频率,对每一频率的对应的场强和电子束能量进行了选取和计算。模拟结果表明:采用目前参数基本能够达到设计要求;辐射频段在2.6 THz附近时装置输出功率和增益都比较高,可以先锁定这个频段附近进行实验的调试;在长波段即1 THz左右时,滑移效应显著,腔增益和输出功率较低,实验实现比较困难,因此在1 THz频段附近必须积极想办法来提高输出功率。     

太赫兹器件测试用高重复频率高压脉冲电源

为了开展太赫兹器件试验研究,设计了高重复频率脉冲电源系统。电源输出脉冲电压30 kV,脉冲电流200 mA,最大重复频率3 kHz,脉冲宽度10~100 μs,采用本地PLC加远程计算机控制模式来实现电源的本控及遥控。对系统的核心部件：充电电源和脉冲开关的拓扑结构进行了研究,并开展了仿真和试验。结果表明：采用LC串联谐振恒流充电技术以提高充电电源工作效率以及在负载打火情况下的可靠性;基于MOSFET并进行优化设计的串联脉冲开关可以获得快速的脉冲前后沿。电源系统的输出指标满足负载工作要求,在高重复频率、打火条件下能够稳定工作。     

Tunable compact high power far-infrared grating free-electron laser

The linear and nonlinear operation of a multiwave grating free-electron laser is described. The radiation is generated by the passage of an annular electron beam through a coaxial waveguide, the central conductor being in the form of a corrugated cylinder. The model includes the effects of self-field forces, beam emittance and gyromotion of electrons in a guide magnetic field. The efficiency is determined by numerical simulation and compared with analytical estimates. A compact source utilizing, for example, a high brightness beam from a carbon fibre electron gun, that is tunable in the wavelength band 35-55 μm with output in the kilowatt range, is shown to be feasible     

Prism tuner for single frequency operation of CW dye laser

A cw dye laser capable of single longitudinal mode operation and linear reproducible wavelenght tuning over a relatively wide spectral range is described. By employing a novel scheme of four intracavity highly dispersive Abbe prisms output powers of 5 mW with a linewidth less than 30 MHz for an input power of 700 mW have been obtained.     

高频大功率磁绝缘线振荡器的理论设计

初步考虑了高频率与高功率的磁绝缘线振荡器的设计问题。用在阴极端头增加发射电流的办法,在C波段理论得到了1.16GW的微波输出功率。利用增加高次谐波的办法在X波段理论获得了270MW的功率输出。     

高频大功率磁绝缘线振荡器的理论设计

 初步考虑了高频率与高功率的磁绝缘线振荡器的设计问题。用在阴极端头增加发射电流的办法,在C波段理论得到了1.16GW的微波输出功率。利用增加高次谐波的办法在X波段理论获得了270MW的功率输出。     

Design and performance of a far infrared,free-electron laser

Abstract

The free-electron laser (FEL) is a device that is capable of high peak and average power, with broad tunability, and with a time structure that can be as short as one picosecond. In the far infrared (λ = 100 ? 1000μm) portion of the spectrum the energy of the electron beam is not too high, there are few alternative bright sources, and there are a variety of interesting applications. Thus, the far infrared (FIR) is a likely region for the development of a table-top FEL that would be a useful laboratory instrument. In this paper the design of a FIR FEL is presented, and its performance characteristics are evaluated.     

CAEP FEL-THz低温系统氦气纯化方法研究

鉴于氦的稀缺性,中国工程物理研究院高平均功率太赫兹大型科研装置(CAEP FEL-THz)低温系统中,必须除去回收粗氦中的杂质,以实现循环再利用。文中通过对常规氦气分离方法的比较和对低温系统低纯度氦气中所含杂质成分的分析,提出了一种基于高压低温冷凝分离和吸附的氦气纯化方法,旨在将低纯度氦气的纯度提升至满足低温系统使用的要求。据此,初步设计了一套氦气纯化系统,介绍了其工艺流程和主要部件。     

Thermal aberrations and high power frequency conversion in a barium nitrate Raman laser

Raman frequency conversion of high average power pulsed Nd:YAG laser radiation into the near IR spectral region in a barium nitrate Raman laser was studied with the emphasis on thermal effects inside the Raman-active medium. The probe-beam technique together with numerical reconstruction, done by integrating the transient heat conduction and paraxial wave equations, revealed dynamics of the induced distortions featuring high-order optical aberrations. By utilizing the Zernike expansion of the reconstructed phase profile and implementing a special focusing geometry of the pump beam, partial compensation of the distortions was realized in a stable configuration of the Raman cavity. Generation of the first-, second-, and third-order Stokes radiation with output power of 17, 9.5, and 5.5 W corresponding to a quantum conversion efficiency of 32, 21, and 13% is reported.     

X波段高功率负载的优化设计与测试

利用三维电磁场仿真软件CST进行了圆形水室水负载的仿真设计,先后设计的两种不同规格的负载驻波比分别为1.032 5和1.055 3,在50 MW的峰值功率下,峰值场强分别为21.16 MV/m和17.57 MV/m;并探究了陶瓷片和水的介电性质对驻波比的影响;测试驻波比分别为1.058 2和1.076 3。对一种圆筒水负载进行了优化设计,结果表明其具有很高的功率耐受水平。最后设计了一种不锈钢干负载,对其吸收齿结构和长度进行了优化,使其更利于加工。使用ANSYS对干负载结构进行了热应力分析,结果显示,最高温度和最大应力分别为83.478 ℃和63.917 MPa,最大形变为0.072 971 mm。     

表面波振荡0.22 THz大功率太赫兹源设计

为研制大功率紧凑型太赫兹源,开展了0.22 THz大功率太赫兹源的理论设计研究。THz源采用表面波振荡器结构。重点研究了慢波结构对太赫兹源产生信号的影响,并对慢波结构进行了优化。结合二极管参数的选取,对该源结构进行了粒子模拟,结果表明：在馈入电压200 kV,电流2900 A的条件下,输出信号频率为0.22 THz,输出功率为19.5 MW,效率约为3.3%。     

Improvement of average laser power and beam divergence of a high pulse repetition frequency excimer laser

Received: 3 January 1997/Revised version: 13 May 1997     

表面波振荡0.22 THz大功率太赫兹源设计

为研制大功率紧凑型太赫兹源,开展了0.22 THz大功率太赫兹源的理论设计研究。THz源采用表面波振荡器结构。重点研究了慢波结构对太赫兹源产生信号的影响,并对慢波结构进行了优化。结合二极管参数的选取,对该源结构进行了粒子模拟,结果表明:在馈入电压200 kV,电流2900 A的条件下,输出信号频率为0.22 THz,输出功率为19.5 MW,效率约为3.3%。     

一种紧凑型宽带高功率微波源设计与测试研究

设计了一款体积紧凑、工作在特高频波段的宽带高功率微波源,系统利用24 V蓄电池供电,Marx发生器作为驱动源,采用四分之一波长开关振荡器调制产生宽带电磁脉冲,激励高功率微带平板天线辐射,测试结果显示系统工作中心频率为425 MHz,远场辐射场强-距离积峰峰值为91.5 kV@1 m,该微波源体积尺寸为871 mm×370 mm×330 mm,含电池质量小于43 kg,拓展了宽带高功率微波技术在无人机、机器人等平台的应用前景。     

激光远场焦斑测试技术的实验研究

 实验研究了激光远场焦斑能量分布测试的三种方法（长焦距透镜法、列阵相机法、Rattle Pair法），对三种测试方法得到的实验数据进行了比对，系统地分析了每种方法的优缺点。结果表明,采用长焦距透镜与一对微楔角劈板组合测试激光远场焦斑的方法更具优势，可减少测试系统引入的像差，并使图像处理过程得到简化。     

Effect of normalized plasma frequency on electron phase-space orbits in a free-electron laser

Irregular phase-space orbits of the electrons are harmful to the electron-beam transport quality and hence deteriorate the performance of a free-electron laser （FEL）. In previous literature, it was demonstrated that the irregularity of the electron phase-space orbits could be caused in several ways, such as varying the wiggler amplitude and inducing sidebands. Based on a Hamiltonian model with a set of self-consistent differential equations, it is shown in this paper that the electron- beam normalized plasma frequency functions not only couple the electron motion with the FEL wave, which results in the evolution of the FEL wave field and a possible power saturation at a large beam current, but also cause the irregularity of the electron phase-space orbits when the normalized plasma frequency has a sufficiently large value, even if the initial energy of the electron is equal to the synchronous energy or the FEL wave does not reach power saturation.