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采用自洽的蒙特卡罗-流体结合模型对溅射过程进行模拟,以了解等离子体粒子行为与溅射参数的关系。溅射过程包括气体放电和溅射原子传输。对于气体放电,蒙特卡罗部分模拟快电子和快气体原子,而流体部分则描述离子和慢电子。对于溅射原子传输,蒙特卡罗部分模拟溅射原子的碰撞过程,而流体部分则描述溅射原子的扩散和漂移。模拟的结果包括:等离子体粒子的密度和能量分布;不同电离机制对气体原子和溅射原子电离的贡献;不同等离子体粒子对阴极溅射碰撞的贡献;溅射原子的密度分布;溅射场和溅射粒子相对于入射离子能量和角度的分布;溅射原子经碰撞后在整个等离子体区的分布。 相似文献
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北京大学射频超导实验室设计了新型超导光电子枪——DC-SC光阴极注入器,目标是为自由电子激光平台提供能量在2~3MeV,脉宽小于10ps,脉冲重复频率为81.25MHz,平均流强约为1mA的低发射度电子束。现在已经建成了DC-SC光阴极注入器实验平台,包括激光驱动光阴极系统,Pierce直流高压加速结构,1.3GHz 1+1/2纯铌超导腔,恒温器低温系统,4.5kW连续波微波系统,1/16分频与同步控制系统,束流诊断系统和能量分析系统等。并且完成了超导腔的静态实验,直流加速结构也经过了100μA低电流测试。实验结果符合设计要求,整体调试后即可以进行束载实验。 相似文献
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用于高平均功率自由电子激光器的DC–RF超导腔注入器 总被引:1,自引:0,他引:1
北京大学超导加速器实验室提出了新型DC?RF超导腔注入器的设计方案.该注入器由皮尔斯引出结构、1+1/2超导腔组成,可以提供高品质的、CW模式或高占空比(1%以上)的电子束.对该注入器进行了分析计算和设计研究,通过改变超导腔首腔腔形以增加聚焦效果,采取措施缩短阴极到超导腔的距离,从而有效地抑制束流发射度的增长.用PARMELA对该注入器进行束流动力学研究,以确定皮尔斯引出结构的形状以及超导腔的同步相位.计算结果表明这种用于高平均功率自由电子激光的注入器的设计方案是可行的. 相似文献
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A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the coaxial transmission line type for the HOM coupler has been designed at Peking University. Experimentally it was shown that the average voltage standing wave ratio of the coaxial transmission line is smaller than 1.08. The experimental results of the stop band characteristics of the TTF-type HOM coupler have been fitted for the simulation. This paper describes the design of the measurement device and discusses the experimental and simulation results of stop band characteristics of the HOM coupler. 相似文献
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Aberration correction of conformal dome based on rotated cylindrical lenses for ultra-wide field of regard 下载免费PDF全文
A new compact conformal dome optical system was designed, and the aberration characteristics of the dome were investigated using Zernike aberration theory. The aberrations induced by the conformal dome at different fields of regard(FORs) from 0° to 90° were effectively balanced by a pair of rotating cylindrical lenses. A design method was introduced and the optimization results were analyzed in detail. The results showed that the Zernike aberrations produced by the conformal dome were decreased dramatically. Also, a complete conformal optical system was designed to further illustrate the aberration correction effect of the rotating cylindrical lenses. Using a pair of rotating cylindrical lenses not only provided an ultra-wide FOR, but also perduced a better image quality of the optical system. 相似文献
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文中分析了利用计算机断层扫描(CT)测量束流二维相空间的物理原理,并从数学上证明了现有方法(CT+四极铁磁场扫描)存在Radon变换角度空档,需要假设某一束流模型进行插值,图像重建的精度不高甚至失真;而结合Cerenkov辐射“双成像法”,可以同时得到束流横向剖面和散角分布的Radon投影,从而将Radon变换角的范围扩展到完整的0—π.文中以一个不对称的束流二维相空间分布为例,给出了计算机模拟实验结果,检验了该新方法进行束流二维相空间图像重建的高精度性和可行性. 相似文献