锑钾铯光阴极制备系统

双碱金属锑化物光阴极在可见光下有高量子效率(QE)、低发射度和强射(RF)频电场,实用真空下寿命较长,产生的高亮度电子束团满足能量回收型直线加速器要求。此类光阴极都含有元素Cs,需在超高真空(UHV)下制备、转移及工作。本文简述了SINAP的双碱金属锑化物光阴极制备装置及各种仪器功能,提出了UHV获得、光阴极基底清洗和K-Cs-Sb光阴极制备过程的方案。通过实验测量了K-Cs-Sb光阴极QE与激光入射功率密度和波长的关系,并构想了基于此制备装置的K-Cs-Sb光阴极的其它性能测试实验。     

高增益自由电子激光光阴极注入器驱动激光系统设计考虑

高增益自由电子激光对电子束团提出了高品质要求 ,只有光阴极微波电子枪能够达到这一目标。光阴极微波电子枪的驱动激光器是这一系统的关键之一。北京大学重离子物理研究所设计的驱动激光系统的指标是提供 2 6 0nm、6～ 8ps宽、5 0 0 μJ的激光脉冲。系统主要由半导体泵浦的钛蓝宝石振荡器、Nd∶YAG调Q泵浦源、再生式放大器、倍频器等组成。系统中采用了腔长调整锁模技术以及相位稳定反馈装置 ,目的是使激光脉冲的时间抖动小于 1 0 ps。     

汤姆逊X射线源激光系统的定时与同步诊断

清华汤姆逊X射线源中,束流动力学性能和对撞时间要求光阴极微波电子枪的触发激光脉冲与加速相位精确同步.本文分别介绍了超快紫外激光系统设计与实现、光阴极微波电子枪定时系统设计,以及同步系统的亚皮秒抖动测量.用高次谐波相位检波器法测量相位噪声功率谱密度可以获得精确的激光-射频相对均方根时间抖动,实验测定为小于200fs[1Hz,100kHz].     

低发射度C波段光阴极微波电子枪设计与优化

自由电子激光(Free Electron Laser,FEL)对电子束的发射度有极高的要求.近年来,可产生短电子束团并且具有高亮度性质的电子枪,是研发高性能FEL的核心部分,也是重要挑战与研究热点.一个很有前景的方向是提高微波电子枪(RF电子枪)内的加速梯度.提高现有电子枪的梯度,需要对电子枪微波场的优化、螺线管的设计...     

阴极测试电子枪结构的设计、试验及改进

阴极测试方法对阴极发射性能评价有着较大影响.本文介绍了一种热阴极性能的电子枪结构测试方法.我们自主设计研制了阴极测试电子枪结构,并采用该测试系统对几种覆膜浸渍钡钨阴极(M型阴极)的电子发射性能进行了初步测试.试验结果表明采用这种阴极性能评价系统是十分有利的.同时根据初步试验的问题,以及对测试结果的分析,对该电子枪结构作进一步的设计改进.     

等离子喷涂硼化镧阴极电子枪

一、引言现代大型医用电子直线加速器电子枪的设计有如下特点: 1.要求电子枪束流在大范围内连续可调。对于一个二极型电子枪系统,枪必须工作在温度限制区域内,故阴极发射的稳定性十分重要。2.行波电子直线加速器通常采用可拆性结构,这就要求阴极必须有较好的抗中毒特性。     

Ir—Ce合金阴极及其应用研究

重点研究了粉末冶金法制备Ｉｒ－Ｃｅ（铱－铈）合金阴极过程中压制压力和烧结温度对发射性能的影响，建立起了一套稳定的制备工艺。试验得到Ｉｒ－Ｃｅ掺Ｗ阴极在１７５３Ｋ时的发射电流密度达１２．４Ａ／ｃｍ２，电流密度保持为１．７Ａ／ｃｍ２，发射试验稳定达１５０ｈ。从机理上验证了它是一种高温大发射电流的发射体。试验还表明Ｉｒ－Ｃｅ阴极具有良好的抗中毒能力。作为应用研究，测量了该阴极在热阴极微波电子枪中的发射性能，微波腔场强约１０ＭＶ／ｍ，工作温度１９１３Ｋ，零场发射电流密度为１０Ａ／ｃｍ２，最大发射电流密度达２１Ａ／ｃｍ２，在２０２０Ｋ时计算零场发射电流密度可达４２Ａ／ｃｍ２。     

Pierce型六硼化镧阴极脉冲电子枪

文章对使用平面LaB_6阴极Pierce型脉冲电子枪进行了研究。这种Φ16×3 mm的阴极具有发射性能稳定、抗中毒、易于激活及较低真空条件等优点。在阳极脉冲电压80kV和阴极温度1360℃时,获得630mA脉冲聚焦电子束流。文中也给出电子枪的某些实验结果。     

钪酸盐阴极电子枪双短脉冲发射实验研究

本工作研究在ns量级双脉冲高压下钪酸盐阴极电子枪电流发射。实验中采用Blumlein线形成ns量级脉冲高压作为电子枪馈入高压,脉冲宽度约为80ns,双脉冲间隔约为300ns。实验结果表明:在消除了空间高频干扰后,法拉第筒测量到的电子枪发射电流脉冲形状与馈入的ns量级双脉冲高压形状非常吻合。由此验证了钪酸盐阴极电子枪对ns级脉冲高压发射响应能力能满足双短脉冲高压工作状态要求,可以作为ns量级多脉冲电子束注入器。     

X光滤片制备方法研究

研究了采用轧制、电阻加热、电子枪和C弧等制备X光滤片的方法,采用天平称重、α测厚仪和光学法等测量X光滤片厚度。分析了各种方法的适用范围及其优缺点,成功地制备了多种X光滤片。     

康普顿背散射X射线源的初步设计

文章提出一种由北京大学DC-SC光阴极注入器驱动、基于超导加速器和能量回收技术（ERL）的康普顿背散射X射线源的设计方案。理论分析和程序模拟表明,利用该方案可获得具有良好单色性的、高通量X射线。     

Study of a photoelectron gun of high current with mediumaccelerating field

A 352-MHz one-cell photocathode electron gun is studied. The simulations with PARMELA are done with two values of peak accelerating fields: 21 and 10 MV/m. Three cavity profiles are compared. The results are also discussed in view of the previous analytic theory. The space-charge effect with peak current greater than 300 A covers the RF effect. The beam qualities are not sensitive to cavity design     

Simulation studies on two-frequency RF gun

Photocathode RF gun is widely used for particle accelerators as an electron source.When driving an RF electron gun at the fundamental frequency and a higher harmonic frequency simultaneously with proper field ratio and relative phase,it generates electron beams of ultralow emittance and a linear longitudinal phase space distribution.Such a gun provides high quality electron beam with low energy spread,small traverse emittance and high brightness.In this paper,the RF design of a 1.5 cell cavity is presented.Simulation results of beam dynamics for the two-frequency gun and a standard single-frequency RF gun are also shown in this paper.In addition,bunch compression with a two-frequency gun is explored.     

PMT光阴极均匀性对液闪衰减长度测量影响的研究

江门中微子实验是测定中微子的质量顺序和精确测量中微子混合参数的实验,中心探测器直径为35.4 m,探测器内液体闪烁体的衰减长度至少为20 m。在液闪研制过程中需实时监测衰减长度的变化,液闪衰减长度的精确的测量成为液闪研制的一个重要课题。本文研究了测量系统中PMT中心位置附近光阴极的均匀性,对比了不同均匀性的PMT在系统中时衰减长度测量结果,得出了PMT光阴极均匀性对测量系统的影响,为提高系统测量的稳定性和精度提供了依据。     

早稻田大学皮秒脉冲辐解装置

A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University. The laser pulse is used for excitation of the photocathode and for generation of white light, which is used for analyzing light in the pulse radiolysis.The system design is shown in Fig. 1. For absorption spectroscopy with wide wavelength region, the white-light continuum was used as analyzing light. The white light continuum was generated by focusing the high intense IR laser into the water cell. The available wavelength was 400-950 nm. Typical data obtained is shown in Fig.2 by using the system. We have performed a deconvolution technique to know the time resolution of our system. For this purpose, we have assumed the shapes of the electron pulse and the laser pulse as Gaussian distributions. Furthermore, the difference of velocity in a sample cell between the electron pulse and the laser pulse due to the refractive index of a sample was also taken into consideration and assuming that the hydrated electrons are formed as a step function and the response function is Gaussian.Thus, time resolution of the system was estimated by deconvolution of the experimental data.We have achieved a time resolution of about 26ps by measuring time profile of hydrated electrons in H2O.     

Cs-Te photocathode RF electron gun for applied research at the Waseda University

A compact electron accelerator based on photo-cathode RF electron gun is under development for applied research at the Waseda University. Higher charge and higher energy are key issues for applications such as pulse radiolysis experiment and laser-Compton X-ray generation. The new RF-gun cavity with cesium telluride (Cs-Te) photo-cathode which has higher quantum efficiency (Q.E.) compared with metal cathodes has been installed. The evaluation of Q.E. of the photo-cathode has been performed and the value obtained is more than 5% at the preparation stage. For understanding the Cs-Te cathode properties and the higher Q.E. operation, fundamental studies by single bunch beam operation have been performed resulting in more than 6 nC bunch charge with a high Q.E. of 2.9%. Additionally, the new RF-gun cavity was improved for obtaining a higher Q value. Higher beam energy, i.e. shunt impedance compared with old type cavity, was observed. The shunt impedance increased by about 20%. These successful results will considerably contribute to the applied research.     

利用二维平台扫描系统研究光电倍增管阴极位置响应

大型高海拔空气簇射观测站(LHAASO)计划中的各种探测器将使用几万只光电倍增管测量探测器收集到的光子数,光电倍增管阴极位置响应的均匀性是影响探测器能量分辨的重要因素之一.为此搭建了由步进电机驱动的二维扫描平台控制LED光源,逐毫米扫描光电倍增管光阴极,测量光源照射光阴极不同位置时的阳极输出信号.实验中对多种候选光电倍...     

Analytical model and simulation of the Schottky effect on a cryocooled bialkali photocathode

A bialkali photocathode with the quantum efficiency(QE) in the range of a few percent was fabricated for the 704 MHz SRF gun at Brookhaven National Laboratory. The photoemission properties of the bialkali photocathode in the superconducting radio frequency(SRF)gun were measured for the first time, and a good beam experiment result was obtained. The performance of the bialkali photocathode was investigated during the commissioning process of the 704 MHz SRF gun. The effect of electric field on the QE of the cryo-cooled cathode was characterized by an analytical model and a code for the first time.     

Photomultiplier Control by a Clamping Cross-Bar Grid

This paper reports on the possibilities for locating light events randomly distributed in a plane by using only one photomultiplier with original electron optics. This experimental 2 inch phototube designed at LEP allows a spatial and temporal control of the electron emission from small elements of the photocathode. The originality of the tube lies in the use of a cross bar control grid embedded in the glass of the window at a short distance (d = 1 mm) from the photosensitive layer. The amplitude of the anode signal obtained in response to a light flash is dependent on the electrical voltage applied to the X or Y wire of the grid associated with the excited element of the photocathode. In such a way it has been shown that the position of a point light source scanning the photocathode plane of the PM could be determined with a resolution of 5 mm. Some results obtained by using a coding process to supply the blocking electrical pulses are given.