刻槽绝缘平行板对电子束的导向效应研究

采用不同材质的刻槽绝缘平行板,包括高纯度石英玻璃、聚四氟乙烯（Teflon）、酚醛树脂（电木）和聚甲醛板（赛钢板）,并在15 pA/mm2 ~14.3 nA/mm2范围内改变入射流强,利用1 500 eV电子束入射上述绝缘平行板,实验研究了上述平行板对电子束的导向行为。实验发现,上述电子束通过上述平行板时存在明显的导向现象,其导向行为与束流流强和绝缘材质无关。据此,可排除绝缘平行板内表面沉积电荷自组织充放电过程中,以绝缘材料的面电阻和体电阻对地泄放的线性形式放电过程。Adopting several grooved parallel plates made by different insulators, such as high-purity fused quartz, Teflon, Bakelite and POM (Polyformaldehyde), and further adjusting the electron beam current in a wide range (tens of pA~tens of nA), the discharging mechanism in the self-organizing charge and discharge processes of electron guiding was investigated and discussed by using 1 500 eV incident electron beam. The present results show that, the electron guiding behaviors are obviously existing when such electron beam is transmitted through the above grooved insulating parallel plates, which are independent on beam current and insulators. Our results suggest that, the possibilities of the accumulated charges on inner-surface of grooved parallel plates linearly discharging through surface and bulk resistances of plates into the ground should be excluded.     

宏观尺寸弯曲石英管对中低能电子束的导向作用

研究了宏观尺寸的弯曲圆柱形石英管对 1 100, 1 300和1 500 eV 3种能量电子束的导向作用, 并对实验结果与相同材质和尺寸的直管的情形进行了分析对比。 实验中利用一个位置灵敏法拉第筒对从石英管出射的电子束进行探测, 获得从管道中出射的电子束流强度在位置灵敏法拉第筒各道上的分布, 其结果显示宏观尺寸石英管对电子束存在导向作用。 与慢速高电荷态离子和绝缘毛细管相互作用的物理过程类似, 这种导向效应是由电荷在管壁内表面自组织充电引起的。 实验还发现, 入射电子束流的强度越强, 其导向作用越明显, 这与微观尺寸毛细管对慢速高电荷态离子的导向作用不同。 石英管导向能力与管的尺寸、 形状及材料之间的关系还有待进一步的系统研究。 It was inevstigated in the experiment that the guiding effect of electron beam with energy of 1 100, 1 300 and 1 500 eV through a bended cylindrical quartz tube with macro sized. A position sensitive Faraday cup was developed and used to detect the electron beam transmitted through the quartz tube, and the distribution of transmitted beam current on each channel of the Faraday cup was acquired. Results indicate the existence of guiding effect which is due to the self organized charge up in the inner wall of the quartz tube similar to that of the highly charged ions. We also found that the guiding ability of the tube is related to the incident beam intensity. The relationship between the guiding ability and the material as well as the size of the tube is to be studied in the near future.     

强流电子束入射弯曲宏观石英管的导向效应研究

研究了强流（~129 nA）、 高能（1 500～1 900 eV）电子束在大角度(9°)弯曲宏观石英管中的导向效应。 实验分别测量了入射流强及能量对出射电子角分布值（FWHM）和传输效率的影响。 实验观察到出射电子角分布FWHM随着入射电子流强和入射电子能量增加变化均不明显; 发现电子传输效率随入射流强增加而增加, 但随入射能量增加而减小, 这与高电荷态离子导向中离子传输效率随入射能量增加而增加的现象相反。 分析发现, 与高电荷态离子导向机制不同, 电子束导向并非是由电子在石英管内壁的自组织充电过程引起的, 而是入射电子与管内壁弹性和非弹性散射碰撞共同作用的结果。 By using an incident electron beam with the high current and high energy, the guiding effect of the bended macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self organized charging effect on the surface of inner wall of quartz tube.     

类氢O、N离子入射Al表面俘获电子布居几率的理论与实验研究

利用“二态矢量模型”详细研究了高电荷态O⁷⁺,N⁶⁺离子入射Al表面时中间里德伯态的形成过程,给出了电子被俘获至不同量子数(n A=2-7)的几率,以及电子俘获至里德伯态最可能的离子-表面距离.计算结果表明,较大的主量子数nA对应较小的里德伯态几率,因此O⁷⁺,N⁶⁺离子入射Al表面时辐射的X射线主要来源于较小的n A至基态的退激.为了验证计算结果,测量了O⁷⁺,N⁶⁺离子入射Al表面的X射线发射谱,并运用FAC程序计算了不同高里德伯态退激到基态的跃迁能(np–1s).实验测量到O,N的K-X射线峰,其特征峰的中心值接近主量子数n=2至n=1的跃迁能,说明发射的X射线主要来源于2p–1s的跃迁,与“二态矢量模型”理论计算的几率一致.     

300和600keV O~(7+)离子与宏观玻璃管的相互作用

实验研究了300和600 ke V的O7+离子与宏观玻璃管内壁的相互作用,利用位置灵敏法拉第筒测量了传输离子的偏转角和传输效率随倾斜角的变化关系,观察到偏转角不等于倾斜角的不完全导向现象。实验结果证实,高能入射离子在玻璃管内壁产生的沉积电势相对于入射离子动能横向分量较小,难以使传输离子沿着玻璃管的轴向出射,从而发生不完全导向现象;并且,入射离子的能量越高,导向效应越不明显。     

平行玻璃板对105 keV Ar7+离子的导向效应

研究了平行玻璃板对高流强（约80 nA）105 keV Ar7+离子的导向效应, 利用一维位置灵敏探测器测量了不同倾斜角下出射离子的强度及角分布。 实验结果表明, 平行玻璃板对Ar7+离子有导向作用。 与离子在微孔膜中的导向效应不同, 从平行玻璃板出射的Ar离子角分布的FWHM随着倾斜角的改变而改变, 并且出射离子角分布最大值处对应的观察角不等于倾斜角。 The transmission of 105 keV Ar7+ ions with high incident current (about 80 nA) through the gap formed by a paired parallel glass plates was investigated. The intensity and angular distribution of the transmitted ions for various tilt angles were measured using a one dimensional position sensitive detector. The results indicate the existence of a guiding effect when Ar7+ ions pass through the gap, but it is different from that for ions passing through nonacapillaries. We found a measurable dependence of the full width at half maximum (FWHM) of the transmitted ions as a function of the tilt angle. In addition, when the gap was tilted with respect to the direction of the incident beam, the observation angle related to the center of the transmitted ions profile was not equal to the tilt angle.     

127°径向位置灵敏柱形静电离子能谱仪

针对高电荷态离子与表面作用产生的溅射离子能谱测量,研制了一台127°径向位置灵敏柱形静电离子能谱仪。利用能量为800 keV的Ar8+离子轰击金属铍靶产生的溅射离子测试了本谱仪。 测试结果表明,该谱仪克服了传统静电谱仪通过扫描工作电压单能量点取谱的缺点, 实现分段取谱——在单个工作电压下可同时获取一段0.85Ec≤E≤1.15Ec范围的能谱, 从而提高测量效率。 A 127° electrostatic coaxial cylindrical energy spectrometer with a radial position sensitive MCP detector is designed for sputtering ions measurement. It has been tested by measuring the energy spectrum of the sputtering ions in the collision of 800 keV Ar8+ bombarding beryllium target. A segment of the energy spectrum (0.85Ec≤E≤1.15Ec) can be obtained at one working voltage (U), which is much efficient than the traditional point to point voltage scanning method.     

高流强电子束在锥形SiO2毛细管中的导向效应

 研究了高流强电子束(1～10 μA)在单根锥形SiO₂毛细管中的导向效应,测量了出射电子的角分布,分析了入射能量对电子传输效率的影响。实验发现：出射电子呈高斯分布且时间稳定性好,随着入射能量增加,电子在毛细管中的传输效率降低,传输效率与入射能量呈负指数关系。实验结果与导向效应模型符合得很好。     

Effects of electron correlation and the Breit interaction on one- and two-electron one-photon transitions in double K hole states of He-like ions(10 ≤ Z ≤ 47)

The x-ray energies and transition rates associated with single and double electron radiative transitions from the double K hole state 2s2p to the 1s2s and 1s^2 configurations of 11 selected He-like ions(10 ≤ Z ≤ 47) are calculated using the fully relativistic multi-configuration Dirac–Fock method(MCDF). An appropriate electron correlation model is constructed with the aid of the active space method, which allows the electron correlation effects to be studied efficiently. The contributions of the electron correlation and the Breit interaction to the transition properties are analyzed in detail. It is found that the two-electron one-photon(TEOP) transition is correlation sensitive. The Breit interaction and electron correlation both contribute significantly to the radiative transition properties of the double K hole state of the He-like ions. Good agreement between the present calculation and previous work is achieved. The calculated data will be helpful to future investigations on double K hole decay processes of He-like ions.     

基于D-S理论的分布式信任模型

针对信任二值性问题,给出了基于委托的信任模型和主观信任模型的信任系统的形式化描述,分析了信任系统中信任的传递和聚合的基本规则,提出并实现了信任传播过程中传递和聚合的计算模型,该模型通过基于证据的D-S(Dempter-Shafer)理论来表达信任度,支持对不同等级的精确度和对未知不确定性的描述,实现了对信任目标的不可知性处理和量化计算.仿真结果显示:当多推荐路径聚合时,该模型可以减小信任的不确定概率从而增加信任的可知性,对模糊投票有较好的处理,可有效地抑制Sybil和Whitewashing等攻击.