中国科学院近代物理研究所自主研制了一台同轴腔电子加速器,能产生10MeV,10mA的辐照电子束,建成后有望成为我国首台国产化的花瓣形电子辐照加速器.为保证该装置运行时的辐射安全,为今后同类型装置的辐射屏蔽设计提供参考,对该加速器开展了辐射屏蔽研究.首先结合装置的使用情况给出了一种地上为主机室地下为辐照室的半地下机房结构,然后采用蒙卡程序FLUKA计算了相关墙体的厚度.在蒙卡计算中,基于同轴腔加速器的束流损失特点,建立了适用于该类型装置的蒙卡源项输入模型,充分考虑了决定辐射场的主要束损点,同时设置相对简单.结果表明:在设定的屏蔽外剂量率目标下,以普通混凝土作为屏蔽材料,主机室的侧墙、顶板和辐照室顶板的厚度分别需要160～220,110～150,150 cm.

High Energy Electron Radiography (HEER) has been proposed as a new material diagnostic technology in recent years. The main features of this technology are the strong penetrating power, high space-time resolution, and large area density diagnostic range. Therefore, it is considered as one of the effective diagnostic methods in the field of high energy density material diagnosis. For further research of HEER, the High Energy Electron Radiography Platform in Lanzhou (HERPL) has designed and built as a dedicated experimental platform of HEER, which is mainly composed of a 50MeV electron linear accelerator based on a thermionic cathode RF gun, and a set of quadrupole magnet image systems. In this paper, the HEER experiment has completed and the spatial resolution of 1μm, the density resolution of 1% was obtained which reached the world record of HEER.

As a new scheme, High Energy Electron Radiography (HEER) was considered as an effective diagnostic tool in the mesoscale sciences due to its high spatial temporal resolution and large area density diagnostic range. Some improvements were implemented to achieve high spatial resolution using a 50 MeV electron beam in Lanzhou, China. These included improving the uniformity of the beam transverse distribution, optimizing the energy spread and increasing the magnet lens magnification. Then the HEER image was collected by a CCD camera with image processing program and in-situ spatial resolution optimization adjustment program. To the best of our knowledge, the achieved spatial resolution of 0.8 mu m constitutes a world record. The details of this experiment are described in this publication.

兰州高能电子成像实验研究平台是中国科学院近代物理研究所建造的唯一专用于高能电子成像及相关领域的实验研究平台,目前已完成第一阶段基于热阴极微波电子枪电子直线加速器的研制,电子束能量50 MeV,最大宏脉冲束流300 mA,达到了设计指标并通过技术测试.开展了高能电子成像实验,空间分辨4 μm,获得了预期结果.

The electron gun with high repetition rate and high average current has a very wide range of applications. This paper presents the design of a microwave grid-controlled high-voltage thermionic electron gun working in CW mode with a bunch repetition rate of 325 MHz and elaborates the experimental principles of this kind of electron guns. Firstly, simulation software EGUN, POISSON (Poisson Superfish) and GPT (General Particle Tracer) are used to accomplish the structure design of a300kV high-voltage DC electron gun and beam dynamics verification.Secondly, to feed the microwave into the gap between the cathode and the grid of the electron gunefficiently, design of a power supply with a scheme of impedance matching from the radio frequency power source to the cathode is completed.Accordingly, a 325 MHz dual-mode coaxial power supply device is designed, and its feasibility is verified and analyzed..

针对兰州高能电子成像实验平台加速器,设计了基于多次改变聚焦强度法的实验来测量束流发射度.采用YAG屏及CCD相机来采集束斑图像,编制了一套完整的计算软件,具有测量方便,计算快速可靠等特点,该测量为后续的高能电子成像实验提供了相关信息.测试结果表明,x方向发射度与理论计算设计接近,y方向发射度与理论计算偏差较大,有待进一步对加速器进行优化调试.

基于EGS5与PARMELA模拟软件组成的高能电子成像系统,对暗场成像的模拟研究发现,通过调节光阑位置实现的暗场成像结果存在失真现象.针对该失真现象提出的改进方案,消除了暗场成像结果的失真.通过对40 MeV电子透射7～224μm的铝样品开展的成像模拟结果表明:40 MeV高能电子暗场成像技术在铝样品厚度小于25μm情况下具有明显的面密度分辨优势,且空间分辨率达到 μm量级,非常适用于高能量密度物质诊断.

Ultrafast imaging tools are of great importance for determining the dynamic density distribution in high energy density（HED） matter. In this work, we designed a high energy electron radiography（HEER） system based on a linear electron accelerator to evaluate its capability for imaging HED matter. 40 MeV electron beams were used to image an aluminum target to study the density resolution and spatial resolution of HEER. The results demonstrate a spatial resolution of tens of micrometers. The interaction of the beams with the target and the beam transport of the transmitted electrons are further simulated with EGS5 and PARMELA codes, with the results showing good agreement with the experimental resolution.Furthermore, the experiment can be improved by adding an aperture at the Fourier plane.

The injection of the electron beam into the ECR (Electron Cyclotron Resonance)plasma by electron gun is a new method for the additional supplementary of the plasma electron, following the aluminum chamber wall and the bias plate, we are expecting for the higher current and charge state of the ion beam with it. However, because of the controllable parameter's variety, the lack of the accumulation of experience and data, and the shortage of convenience in designing and experimental practicing compared by biased disk and other means,it has always not been intensively studied. In this article, we take the 18 GHz ECR Ion Source using evaporative cooling technique as experimental platform, do the experiment of injecting electron into ECR plasma base on the simulation result of the electron beam's path in ECR's chamber by the 3D simulation software CST the particle studio. It shows that a pulsing leap of the current of the extracting ion beam appears when the injecting electron's energy is above 1800 eV. In the mean time, the top of the pulse and the average current of the ion beam rises, the ionization state moves to a higher level. This phenomenon can be turned on and off by controlling the experimental condition. At the last part of the article, we discuss this improvement of the current and charge state of the ion beam despite of the position's missing between the injection of electron beam and the resonance surface, and hold the opinion that this phenomenon is positive to both pulsed and direct beam.

AbstractBackground: Compact D-D neutron generator provides the stable and reliable 2.5-MeV neutrons with higher neutron yields, which can be applied in neutron activation analysis, fast neutron radiography, and detection of explosives and drugs. In this work, a control system of neutron generator was developed to realize remote adjustment and measurement.Purpose:The control system of neutron generator is used to adjust and monitor field devices remotely to ensure normal work for neutron generator.Methods:According to the characteristics of the devices’ interface, serial port server is used as the hardware for control system. Based on LabVIEW, the control system integrates and monitors all equipments of neutron generator, which duly saves and queries main operating parameters of neutron generator by accessing MySQL database.Results: The control system operates stably for long time, and is applied successfully to debug and test of the neutron generator.Conclusion:The design of control system for compact D-D neutron generator meets the designed goal, and realizes remote control mode for adjustment and measurement.

A new scheme that cooling international Linear Collider (ILC) positron source target by touching thermal conduction (TTC) is presented by Argonne National Laboratory (ANL). Recent results of simulation for cooling the iron targets with 300 and 450 W heat reservoir by ANSYS and experiment of cooling the iron target with 300 and 450 W friction heat reservoir at Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS), have proved that the TTC has good cooling effect in low temperature zone(20 ℃～50℃), and preliminarily verified the feasibility of TTC for cooling the ILC positron source target.

An X‐ray irradiator ,which can be applied in the fields of blood irradiation , vaccine production ,food processing ,biological experiment ,etc .,was described .It gen‐erates X‐ray for applications by bremsstrahlung from electron beam bombardment at metal target .Compared with isotope‐ray irradiation facility ,the X‐ray irradiator has the advantages of higher safety ,better irradiance uniformity and controlled dose .The paper also described the measurement results of the newly developed X‐ray tube .The results show that the new X‐ray tube can meet the requirement of industrial application .

Based on the technology of the DG series electron accelerator, a 500 kV/150 mA electron acceler-ator was designed and manufactured at IMP(Institute of Modern Physics, Chinese Academy of Sciences). The new structure of high voltage and shorter accelerating tube have been used in this accelerator for high current. The specific features of this accelerator are compact of structure and higher power conversion efficiency. It has already passed the running test of 500 kV/170 mA, and the parameter is better than the designed value.

In order to put the Pulse Line Ion Accelerator (PLIA) concept to its practical application, a small experimental platform was built. It was found that the actual axial electric field is smaller than the theoretical calculation, so the accelerated ions will enter into the deceleration zone before leaving the helix, which will seriously affect the acceleration process. Based on the improved parameters, the He+ with 24 keV is accelerated to 55 keV, and the proof-of-principle experiment is completed on this platform.

Dielectric wall accelerator (DWA), towards high gradient acceleration field (30 MeV/m–100 MeV/m), is under development at Institute of Modern Physics. A prototype was designed and constructed to prove the principle. This needs a short pulse high current electron source to match the acceleration field generated by the Blumlein-type pulse forming lines (PFLs). In this paper, we report the design and test of a new type short pulse high current electron gun based on principle of vacuum arc discharge. Electron beams of 100 mA with pulse width of 10 ns were obtained.

为了提高DG型电子加速器束流扫描均匀度、解决束流中心偏移、提升束流引出效率,开发了一种既可实现X,Y两相互垂直方向均匀扫描又可以实现束流中心自动对中调节的扫描系统.介绍了扫描磁铁及其电源参数的选取依据,阐述了将扫描磁铁和束流校正线圈进行整体式设计的扫描系统扫描电流成形方式及自动对中电路信号调制过程,包括为提高加速器运行安全性而设计的连锁保护信号.产业化现场使用事实已证明,该系统设计完全达到了设计要求,具有优良的扫描均匀度和长时间工作稳定可靠性.

To accelerate intense, short pulsed heavy ion beams to the energies of interest for studies of high energy density physics and warm dense matter, the Pulse Line Ion Accelerator (PLIA), of which the axial acceleration gradient can achieve several MeV per meter with realistic helix parameters at very low cost, was developed in recent years. A simple prototype of PLIA for a proof-of-principle experiment called the Lanzhou Test PLIA was designed and constructed at the Institute of Modern Physics in Lanzhou, and the test result matches the calculated result well. The pattern of the axial electric field Ez and the velocity of the traveling wave were simulated by CST.

DG-series industrial electron accelerators of intermediate frequency transformer type have been successfully researched and developed in the Institute of Modern Physics,Chinese Academy of Science. The DG-2.5 accelerator with beam energy range of 1.0-2.5MeV,maximum beam power of 90 kW and length of extraction window up to 1000 mm,is suitable for many kind uses of the radiation technology. DG-1.2 accelerator,another type with beam energy range of 0.8-1.2 MeV and beam power of 50 kW,was also designed and constructed. The two accelerators have been tested with long-term operations. They were proved as E-beam irradiators of high reliability,very low malfunction rates and high efficiency.

The configuration and performance of high voltage generator(HVG) of a high power low-energy electron accelerator, designed for industrial applications, were introduced in this paper.The simulating circuit model parameters of the HVG were determined based on its basic transformer-type working principle, and then the Matlab software was used to simulate steady work condition of the HVG.Furthermore, the instant voltage distribution along the cascades of the HVG was analyzed under the malfunction of breakdown between the high voltage electrode and the ground electrode.After that, the parameters of HVG were partly adjusted according to the simulating result, and performance of the equipment was improved as a result of the adjustment.In addition, the interlayer breakdown between the sections of cascades was simulated by Matlab, and some improving methods were adopted to enhance the performance of HVG for protecting the equipment during the high voltage breakdown.