辐照食品直线加速器电子枪设计

本文介绍了中国科技大学国家同步辐射实验室研发的一台食品辐照保鲜用直线加速器中电子枪的设计.通过枪体内电磁场模拟计算、优化电子枪形状、并且在考虑空间电荷效应情况下对电子束发射过程进行模拟,得到了满足设计要求的束斑尺寸.另外对电子枪的加工和调试过程也进行了介绍,通过电子枪高压老炼及出束实验表明,其各项参数性能均达到设计要求.另外对直线加速器螺线管聚焦线圈漏场对束流的影响也作了讨论,采用相应措施可增加磁屏蔽,减小漏场影响,保证束流品质.     

可更换阴极热子的辐照加速器用电子枪

本文介绍了工作电压为60 kV、峰值电流为550-600 mA、射程要求为60 mm、注腰不大于Φ4 mm的电子枪的研制.该电子枪用于辐射加工电子直线加速器(10 MeV 1.5 mA).为降低加速器的运营成本,该电子枪特别设计为可更换阴极热子型.采用Egun、Mafia等软件进行模拟计算,基本按照速调管生产的工艺流程...     

10 MeV辐照电子直线加速器真空系统运行情况

10MeV辐照电子直线加速器的真空系统自2004年5月安装完成后,到目前已运行8个月,其运行状况基本正常。本系统使用5台钛泵,保证达到整个加速器对真空度的要求,使加速器正常、稳定地工作。5台钛泵分别放置于波导、电子枪阴极、加速管入口、加速管出口和扫描盒处。为保证电子枪能够     

宽范围高精度电子枪系统的设计与验证

“空间环境地面模拟装置”是“十二五”国家重大科技基础设施项目,针对其子项目“低能电子加速器及束线”中辐照加速器的要求,在原有二极电子枪基础上增加了控制栅极。使用CST Particle Studio仿真研究了电子枪部分结构参数变化对引出束流强度的影响,设计出产生50 mA高品质束流的电子枪,并用PBGUNS(Particle Beam GUN Simulation)软件对设计结果进行验证。最后在电子枪实验平台上检验了电子枪结构参数变化对引出束流强度的影响规律,并对电子枪结构进行了优化。结果表明优化后的电子枪能够以阴极初级加热电压作粗调、栅极电压作细调的方式引出1μA～50 mA高品质电子束。     

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。     

10 MeV辐照电子直线加速器真空系统改造

为达到更好的真空度,保证实验效果更佳,2005年12月对10MeV辐照电子直线加速器的真空系统进行改造。改造后,系统仍使用5台钛泵保证整个加速器对真空度的要求,使加速器正常、稳定地工作。5台钛泵位置保持不变,波导使用原钛泵,电子枪阴极处钛泵由3L/s变为8L/s,加速管入口处钛泵由2     

强流栅控电子枪设计分析

电子枪是超高真空电子器件,可用于各类加速器的束流源与功率源中,是加速器与微波电子管的主要与关键部件之一.结合某辐照加速器电子枪实际需要,对其束流光学系统进行了计算机模拟和优化设计.模拟结果表明该电子枪在80 kv高压下工作时,输出电流可以达到5 A以上,束流发射度、枪区电场以及束腰半径可以满足该加速器运行的需要.电子枪...     

宽范围高精度电子枪控制系统的研制

本文针对"1.2 MeV/10 mA高频高压型电子加速器及束线"项目中钨丝阴极热发射电子枪的控制需求,在了解了系统组成和工作原理的基础上,采用三极式平板热阴极发射电子枪,阴极材料使用钨丝,灯丝加热电源由发电机供电,引出电压从加速管电极分压获得。通过设计一种基于可编程逻辑控制器(Programmable Logic Controller,PLC)的控制系统,实现了电子枪引出1μA～50 mA 4个数量级范围的直流电子束。该控制系统采用PLC作为设备控制器,LabVIEW软件作为用户界面,通过通信协议(Object Linking and Embedding for Process Control,OPC)接口实现控制软件与设备控制器的通讯。实验测试表明,系统具有可靠稳定、灵活高效等特点。     

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。     

基于Poisson Superfish和General Particle Tracer的高亮度高平均功率电子枪设计

设计一个高压350 kV、平均流强10 mA、束流发射度低于20 μm-rad的电子枪.阴极为光阴极时,峰值电流大,导流系数较大,采用Pierce法设计球面阴极结构电子枪.阴极为热阴极直流时,峰值电流较小,导流系数较小,考虑设计一个平面阴极电子枪.用Poisson Superfish构建电子枪的基本结构,再用Gener...     

Experimental results from an ECR source using an octupole

The large superconducting ECR source, ECREVIS (Louvain-la-Neuve) has shown better charge state distribution (CSD) than smaller sources like MINIMAFIOS or the Berkeley source. Computer simulation indicates that the reason could be a lower average electron energy in the smaller sources. It has been suggested by Jongen that the size of the magnetic gradients in the source could be the energy limiting factor, and that the average electron energy could be increased by replacing the usual sextupole by an octupole. After an extensive series of tests, the sextupole of the Berkeley source was replaced by an octupole. After modification, the CSD have been substantially improved in the direction of higher charge states, with a substantial reduction of low charge state intensity. The intensity of higher charge states like argon 14+ or krypton 18+ increased by one order of magnitude. The new CSD are now very similar to those of the large ECREVIS source, indicating a probable gain in average electron energy.     

Sheath Criterion for an Electronegative Plasma Sheath in an Oblique Magnetic Field

The sheath criterion for an electronegative plasma composed of hot electrons,hot negative ions and cold positive ions in an oblique magnetic field is investigated.We discuss the effects of negative ions and external magnetic field on the sheath criterion.We find that the ion Mach number is of relatively low value because of Coulomb attraction between positive and negative ions.Also the ion Mach number depends on the magnitude and the angle of the magnetic field as well as the initial velocity of ion flow.     

Mikrosondenuntersuchungen an bestrahltem urancarbid

A shielded Cameca microbrobe, MS 46, was used to examine a UC sample canned in SAP and irradiated to a burnup of 0.7%. An annular zone at about 40% of the outer sample radius was seen to contain precipitates loaded with fission products: microbrobe analysis showed the precipitates to be U₂ (Tc, Ru, Rh)C₂. Small amounts of palladium can be stabilized in this phase. Zirconium and molybdenum were verified in homogeneous distribution in the fuel. The Vickers hardness of the irradiated UC is 1000–1200 kp/mm². No signs of incompatibility with the canning material were detected.     

A wire probe as an ion source for an electron beam ion trap

A thin wire probe inserted near the electron beam in an electron beam ion trap provides a source of ions for the trap. The wire can be plated with a small amount of source material permitting the use of rare or expensive materials. Here we present results on tests with probes of various materials to demonstrate the success of the technique. In one case a sample of approximately 100 ng of ²³³U was plated on a platinum wire tip and used to continuously fill the trap for 10 days.     

Performance evaluation of an advanced integral reactor against an anticipated transient without scram

Performance evaluation of KAERI’s advanced integral reactor against an anticipated transient without scram has been carried out with the transients and setpoint simulation/small and medium reactor code, by considering a decrease in the heat removal by the secondary system, a loss of offsite power and an inadvertent control rod withdrawal event as an initiating event. In a decrease in the heat transfer by the secondary system and a loss of offsite power, the reactor coolant system pressures can be maintained below 110% of the design pressure during the transition period due to the effect of the large negative moderator temperature coefficient. On the other hand, in an inadvertent control rod withdrawal event, the pressure of the reactor coolant system increases up to the ASME service level C stress limit due to a high reactivity insertion into a reactor core by the adoption of a boron free core concept. Therefore, a hardware installation against an anticipated transient without scram is essential to mitigate the consequences resulting from an inadvertent control rod withdrawal event. A diverse protection system, which is an independent and diverse reactor shutdown system that is initiated by the signals of a high core power or a high pressurizer pressure, is adopted in the advanced integral reactor. According to the reassessment results by considering the diverse protection system for a reactor shutdown, the diverse protection system is helpful in mitigating the consequences of an anticipated transient without scram.