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 concept of granular flow target was proposed very recently and there are many potential advantages of the target on flow constancy, energy deposition and heat removal, etc. In this work first loop of granular flow target is built and an electron beam coupling experiment is reported, which aims to test the flow constancy, energy deposition and heat removal of the granular materials. The results show a good constancy of the dense granular flow and indicate granular flow as a candidate for energy removal. Moreover, there is a consistence in flow rate and temperature rise between experimental and numerical studies. This work supports the idea of granular target and is valuable for the following ADS facilities and granular flow target design.

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 .

Polyacrylonitrile/polyethylene oxide (PAN/PEO, 5% PAN and 5% PEO) was irradiated by 1.0 MeV electron beam with different doses in this work. FTIR result indicated that PAN/PEO crosslinked after irradiation. It was pointed out by analysis that gel fraction of PAN/PEO increased with EB irradiation dose. The increasing rate of gel fraction could be divided into three stages, which were rapidly increasing stage (0～39 kGy), decreasing stage (39～130 kGy) and stable stage (more than 130 kGy). Theoretical calculation results showed that the values fitting by half-experience equation presented by Zhang Wanxi were closer to the measured values than Charlesby-Pinner equation fitting ones because of the introduction of rigidity parameterβ in the half-experience equation (for PAN/PEO,β was 0.166). The curve of crosslinking degree vs irradiation dose showed that the crosslinking degree increased with the irradiation dose, and it could provide a referential irradiation dose when materials with fixed crosslinking degree were needed in new functional materials.

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.

An electron diode using a short section of dielectric wall accelerator (DWA) has been under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. Tests have been carried out with spark gap switches triggered by lasers. The stack voltage efficiency of a four-layer of Blumleins reached about 60–70% with gas filled spark gap switching. The generated pulse voltage of peak amplitude of 23kV and pulse width of 5ns is used to extract and accelerate an electron beam of 320mA, measured by a fast current transformer. A nanosecond pulse width electron diode was achieved successfully. Furthermore, the principle of a DWA is well proven and the development details and discussions are presented in this article.

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.

A simulation study of a short-pulsed proton injector for, and beam transport in, a dielectric wall accelerator (DWA) has been carried out using the particle-in-cell (PIC) code Warp. It was shown that applying “tilt pulse” voltage waveforms on three electrodes enables the production of a shorter bunch by the injector. The fields in the DWA beam tube were simulated using Computer Simulation Technology’s Microwave Studio (CST MWS) package, with various choices for the boundary conditions. For acceleration in the DWA, the beam transport was simulated with Warp, using applied fields obtained by running CST MWS. Our simulations showed that the electric field at the entrance to the DWA represents a challenging issue for the beam transport. We thus simulated a configuration with a mesh at the entrance of the DWA, intended to improve the entrance field. In these latter simulations, a proton bunch was successfully accelerated from 130keV to about 36MeV in a DWA with a length of 36.75cm. As the beam bunch progresses, its transverse dimensions diminish from (roughly) 0.5×0.5cm to 0.2×0.4cm. The beam pulse lengthens from 1cm to 2cm due to lack of longitudinal compression fields.

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 Ripple coefficient is one of the important factor for the stability of industrial high voltage electron accelerator.Accelerator can't work well when the ripple coefficient is high.The increment of the measured ripple values becomes very large with the increase of the accelerator load current.From the simulation with finite element method of high voltage generator,we found that the leakage magnetic field was the most important reason for the results of ripple measurement.The ripple was measured after changing the frame of the high voltage generator to suppress the leakage magnetic field.It can be concluded that the actual value is acceptable to the accelerator and the measured high ripple coefficient is not the reason of malfunction of this high power electron accelerator.