小型高压悬浮LaB_6电子枪研制

介绍了一种小型高压悬浮LaB_6电子枪的研制。该电子枪选用具有较强抗氧化能力的LaB_6作为阴极,通过隔离变压器,直接悬浮加速电压,并采用三圆筒透镜作为电子光学系统,减小了电子枪机械设计难度,提高了束流品质。测试发现,该电子枪在1 500 K时即能达到最高电流密度,电子束能量2.5keV,靶上流强2μA,束斑直径3 mm,焦距动态范围375 mm。目前该电子枪已成功应用于中国科学院近代物理研究所带电粒子与表面相互作用实验平台。     

高压型低能大功率辐照加速器电子枪研制

低能大功率辐照加速器广泛用于辐照加工产业。本工作研制出一台二极电子枪作为高压型低能大功率辐照加速器的电子源,并通过出束实验对其加以优化,最后确定了二极电子枪的最佳结构、尺寸及运行参数等。结果表明,从电子枪引出电子束的能量为5~25 keV,流强为60~100 mA,束斑为15~30 mm,半散角为0.6°~1.6°,不稳定度好于±0.6%。该电子枪工作稳定,寿命长于5 000 h。     

单粒子微束辐照装置的束流光学计算

利用束流光学计算程序TRANSPORT和TURTLE对基于2×3MV串列静电加速器的单粒子微束细胞精确照射装置的束流传输光学进行了一阶近似计算,得到了包括束流包络、束流相图、束斑大小及束流发散程度的相关数据.计算结果表明,对于能量1.5 MeV,经2 mm×2 mm狭缝入射且初始发散角x'～y'≤3mrad的典型质子束...     

750KeV,50mAH—RFQ预注入器调整结果

文章介绍西德DESY研究所750keV负氢离子预注入器的调整结果。通过提高弧流,磁控管型H~-离子源可以引出18keV,60—80mA的H~-脉冲离子流。发现外部磁场可以在螺旋管内部感生一个方向大体相同的磁场。在低能输运段,离子束空间电荷中和所需的时间约100μs。在离子源引出束流约65mA时,经两对螺旋管聚焦和RFQ加速后可以获得能量为750±8.8keV,聚团半宽度约0.8ns,发射度约3mm·mrad,束流为52mA的脉冲H~-流;其中33mA以上的束流处于1mm·mrad以内。     

HI－13串列加速器升级工程在线同位素分离器高质量分辨谱仪物理设计

HI－13串列加速器升级工程中的在线同位素分离器(ISOL)高质量分辨谱仪要求20000的质量分辨率。本工作采用大小铁双能量结构削弱能量色散，有效解决了束流能散过大导致的谱仪质量分辨率低的问题。结果表明：当束流高斯分布宽度为0.06mm和10mrad时，谱仪的质量分辨率达到了33400；若考虑加速段引入的0.002%能散，谱仪最终的质量分辨率为20000。     

高分辨快电子能量损失谱仪的改进

新研制的成功的电子能量损失符合谱仪是由电子能量损失谱仪、正离子飞行时间质谱仪、负离子习行时间质谱仪及相应的电子学符合测量系统构成。该系统可以同时获得电子与原子分子碰撞后散射电子、电离或解离正离子、解离负离子或电离电子的信息。利用该装置测量了一氧化碳分子的光电离效率曲线及其离子碎片的部分光学振子强度密度。     

用于质子直线加速器的强流ECR离子源

介绍了正在研制的一台强流ECR离子源。它的目标是用于加速器驱动的次临界系统(ADS)。两种结构的离子源均获得了较好的结果。在30 keV能量下,氢离子最大束流达到100 mA,质子比好于85％,引出束流密度最高可达340 mA/cm2。初步测定的发射度约为0.11πmm·mrad。已通过了100 h的连续运行考验。     

用于质子直线加速器的强流电子回旋共振离子源

研制了一台用于加速器驱动次临界系统 (ADS)的强流电子回旋共振离子源。在 30keV能量下 ,引出的氢离子最大束流达到 1 0 0mA ,质子比好于 85 % ,引出束流密度最高可达 34 0mA/cm2 。初步测定的发射度约为 0 1 1πmm·mrad。已通过了 1 0 0h的连续运行考验。     

水平散射几何中子反射谱仪的三盘斩波器设计

为提高水平散射几何中子反射谱仪分辨,希望谱仪前端的中子斩波器能斩出脉冲强度大水平发散度较小的中子脉冲束流,采用新设计的三斩盘斩波器模型,运用Mcstas程序软件考察了不同物理参数下三盘斩波器的中子斩波特性.获得了特定物理条件下相关物理参数对束流强度和发散度的影响关系曲线.计算结果可为水平散射几何中子反射谱仪中三盘斩波器的设计及物理参数的选择提供理论依据.     

强流RFQ注入系统研制

本文介绍研制的强流RFQ注入系统。系统包括强流离子源、聚焦透镜、束流切割器等，注入系统在RFQ入口处形成了束流能量75keV、流强42mA、α参数为1．79、β参数为0．0596mm／mrad、束流脉冲频率1-100Hz、束流占空比1％-100％、发射度小于95．2πc mm mrad的质子束，可满足强流RFQ对束流注入品质的要求。     

螺线管磁场旋转束流法测量Mini-LIA电子束能量

介绍了螺线管磁场旋转束流法的能量测量原理和在Mini-uA上开展的单脉冲电子束能量测量实验.通过测量束流在螺线管磁场中的旋转角度,得到Mini-LIA出口处电子束能量,与加速器总的加速电压符合得很好.分析了旋束法的测量误差和应用特点,给出了旋束法测量的适用范围.     

计算脉冲电子束辐照下能量沉积剖面的新方案

脉冲电子束辐照材料试验研究中,束流电子具有不同的速度和角度分布。但数值模拟计算一般都考虑电子束垂直入射靶材料,这可能导致数值计算结果与试验结果不符。针对该问题,提出了一种计算电子束辐照下能量沉积剖面的新方案,利用MCNP(Monte Carlo N Particle Transport Code)软件对铝、铜、钽金属材料在电子束辐照下的能量沉积进行模拟,分析了电子束垂直入射与带有角度分布入射时能量沉积的差异,为解释电子束辐照试验测量数据与理论计算结果之间的差异提供了依据。     

Focused electron beam transport through a long narrow metal tube at elevated pressures in the forevacuum range

We present here our investigations of the features of focused electron beam transport in free space at elevated pressures of a few pascals.We have explored the effect of the beam accelerating voltage,operating gas pressure,and magnetic focusing upon the trajectory of beam electrons in the crossover region,in particular on the beam convergence and divergence angles.It is shown that for the forevacuum pressure range of 2-5 Pa explored,a distinctive feature of the propagation of a focused electron ...     

Beam and image experiment of beam deflection electron gun for distributed X-ray sources

Distributed X-ray sources comprise a single vacuum chamber containing multiple X-ray sources that are triggered and emit X-rays at a specific time and location. This process facilitates an application for innovative system concepts in X-ray and computer tomography. This paper proposes a novel electron beam focusing, shaping,and deflection electron gun for distributed X-ray sources.The electron gun uses a dispenser cathode as an electron emitter, a mesh grid to control emission current, and two electrostatic lenses for beam shaping, focusing, and deflection. Novel focusing and deflecting electrodes were designed to increase the number of focal spots in the distributed source. Two identical half-rectangle opening electrodes are controlled by adjusting the potential of the two electrodes to control the electron beam trajectory, and then, multifocal spots are obtained on the anode target. The electron gun can increase the spatial density of the distributed X-ray sources, thereby improving the image quality. The beam experimental results show that the focal spot sizes of the deflected(deflected amplitude 10.5 mm)and non-deflected electron beams at full width at half maximum are 0.80 mm 90.50 mm and 0.55 mm 90.40 mm, respectively(anode voltage 160 kV; beam current 30 mA). The imaging experimental results demonstrate the excellent spatial resolution and time resolution of an imaging system built with the sources, which has an excellent imaging effect on a field-programmable gate array chip and a rotating metal disk.     

Charge evolution and energy loss associated with electron transmission through a macroscopic single glass capillary

Charge (time) evolution and the angular dependence of incident electrons in the range 300-1030 eV through a single macroscopic glass capillary was studied. Charge measurements were done at a sample tilt angle of ψ = 2? for observation angles θ = 0? and 0.5? (both ψ and θ were measured with respect to the incident beam direction) at incident energies of 520.7 and 824.5 eV using a parallel-plate spectrometer. After equilibrium of transmission, electrons had lower average centroid (mean) energies than the respective primary beam values. Centroid energies of transmitted electrons at the centroid of the angular distribution (where the observation angle θ is nearly equal to tilt angle of the sample ψ) were found to decrease exponentially with increasing sample tilt angles for all the measured electron energies. This energy loss is attributed to inelastic scattering of electrons with the inner wall of the sample close to the capillary entrance. Furthermore, the centroid energies of the transmitted electron angular distributions at 520.7 eV were found to lose energy for angular positions away from the capillary axis (angular centroid position) for all tilt angles, indicating a higher degree of inelastic scattering at the edges of the angular distributions.     

Characteristics of the beam injection system in an electron LINAC

The main characteristics of an electron beam injection system are described; the system is used for injecting and focusing electron beams into the acceleration structure of an 10 MeV linear electron accelerator. The beam injection system consists of a Pierce convergent diode-type electron gun with pulse modulator for power supply and a thin axially symmetric lens. The perveance and the capture coefficient were optimized by the analogical resistors network. This type of injection system was used in the linear electron accelerators: ALIN - 3 MeV, ALIN - 10 MeV and ALID − 8 MeV, performed at NILPRP^∗ Bucharest, Romania.     

一台300kV电子帘加速器辐照箱屏蔽物理设计

介绍一台电子能量为300keV、束流强度为60mA的电子帘加速器辐照箱的屏蔽物理设计。箱体厚度为1．5cm的铅。     

双阳极电子枪测量系统研制与实验

为测量双阳极电子枪的输出束流品质,设计了一套完善的测量系统。使用该测量系统对双阳极电子枪进行测量。实验结果表明,增加中间电极可提高电子枪输出束流流强并改善横向聚焦。     

电子束辐照对多酚氧化酶活性及结构的影响

应用圆二色谱及SDS-PAGE技术分析电子束辐照对多酚氧化酶(Polyphenol oxidase,PPO)活性及结构的影响。结果发现:电子束辐照可在一定程度上降低PPO酶活性;圆二色谱分析发现电子束辐照处理后,PPO酶蛋白质二级结构相对含量发生改变,但a螺旋、b折叠和b转角总含量在吸收剂量4.83 kGy时总量变化不大,当吸收剂量4.83 kGy时,随着剂量的增加含量不断下降,无规则卷曲呈上升趋势。SDS-PAGE电泳实验结果表明,辐照处理下PPO酶同时发生交联和降解反应。上述结果提示电子束辐照对PPO酶活性有一定的抑制作用。