排序方式: 共有90条查询结果,搜索用时 343 毫秒
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讨论了不同发射机理对铁电阴极材料性能的要求,对PZT(锆钛酸铅)系铁电陶瓷工艺过程中的关键步骤进行了研究。通过掺杂改性和改进预烧条件等手段,有效地改善了材料的性能参数,制备出相对介电常数大于3 000的弛豫相铁电陶瓷和压电常数大于500×10-12C/N的铁电相铁电陶瓷。在初步的发射实验中,使用改进工艺后的PLZT8/65/35制备的铁电阴极,触发脉冲5.4 kV时,获得的发射电子电流密度达到800 A/cm2/sup>,远大于C-L定律计算的发射电流。 相似文献
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高能X射线双能成像法中的物质识别 总被引:4,自引:0,他引:4
研究了边界能量为1—10MeV的高能X射线成像系统中采用双能成像法识别物质问题. 通过研究其物理机理, 提出了一个近似线性的数学模型; 定义了物质识别灵敏度用于评价物质识别效果; 发现了双能X射线的最优能谱分布区间. 提出并验证了面向最优能谱分布区间的双能X射线能谱调制方法, 大大提高了物质识别灵敏度, 并较好解决了不易识别薄物质的问题. 建成了9MeV/6MeV交替双能成像实验样机, 获得了物质识别着色图像. 相关实验研究结果与理论研究符合得很好. 相似文献
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杜应超 陈寒 张鸿泽 高强 田其立 迟智军 张智 查皓 施嘉儒 颜立新 邱睿 程诚 杜泰斌 李任恺 陈怀璧 黄文会 唐传祥 《强激光与粒子束》2022,34(10):104010-1-104010-9
基于高亮度电子束与超短强激光相互作用的逆康普顿散射X/γ射线源具有单色性好、能量可调、偏振可控等特点,在核安全及核安保领域具有广泛的应用前景。清华大学将研制国际上首套能量达MeV的紧凑准单能伽马源装置并开展包括先进辐射成像、基于核共振荧光的物质分析检测等应用工作。给出该光源设计方案,以及针对其关键性能指标进行的优化及光源最终性能指标。目前已完成光源的设计,正在进行部件的加工采购,预计将于2023年启动装置的安装调试工作,于2025年完成项目的调试和验收。 相似文献
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通过建立X波段同轴磁控管模型,对起振过程进行PIC模拟,结果表明:当衰减瓷损耗角正切大于0.010时,起振过程中可能受干扰模影响,但均能正常工作;当选用损耗角正切为0.001或不具有衰减性能的材料时,磁控管可能无法正常工作。因此同轴磁控管中需要选用损耗角正切大于0.010的电介质材料。进一步对该磁控管进行冷态微波特性模拟研究,重点分析了磁控管主模、N/2-1干扰模在不同参数衰减瓷下的品质因数,模拟结果表明衰减瓷位置合理,当损耗角正切大于0.010时,对N/2-1模的吸收效果明显改善,验证了PIC模拟的结论。 相似文献
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Backward wave oscillators (BWOs) driven by intense relativistic electron beams are very efficient means of producing high-power microwaves. However, the efficiency of conventional BWO is lower than 30%. An X-band oversized BWO with non-uniform slow wave structure is designed to improve RF output characteristics. In particle-in-cell simulation, a high power microwave with a power of 8.0 GW and efficiency of 40% is obtained, compared with that of 30% obtained in a conventional relativistic BWO. 相似文献
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Characteristics of terahertz generated from picosecond coherent transition radiation ultrashort electron bunches 下载免费PDF全文
This paper presents a method of generating terahertz (THz) coherent transition radiation (CTR) from picosecond ultrashort electron bunches including single and train bunches, which are produced by a photocathode radio frequency gun. The radiation characteristics of THz CTR including formation factor and energy spectrum are analysed in detail. With the help of a 2-dimensional particle-in-cell simulation, the radiation characteristics including power, energy and magnetic field are analysed. The results show that the radiation frequency can be adjusted by tuning the repetition frequency of the train bunch and the energy can be enhanced with the train bunches. 相似文献
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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. 相似文献