Precision Phase Adjustment of a Linear Accelerator High Power Waveguide Feed Network

Each klystron of the SLAC accelerator feeds four consecutive 10-foot accelerator sections through approximately 25 feet of earth shielding. The high power waveguide network which divides and guides the power to the four sections is adjusted so that the rf waves traveling within the accelerator sections are, at the end of each section, phased within ± two degrees of an ideal wave traveling at the velocity of light. A modulated reflection technique is used to compare the electrical phase length from a single input port through the four arms of the network during adjustment. The inclusion of the previously tuned accelerator sections in the network allows the total phase error to be minimized if careful control is exercised over the section terperatures. The measuring system, the reflection modulators, and the possible errors involved are discussed.     

Status of Work on the VÉPP-5 Injection Complex

The VÉPP-5 injection complex under construction at the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences is a powerful source of intense electron and positron bunches at 510 MeV, which covers all needs of the electron–positron colliding beam setups currently operating and under construction at the Institute of Nuclear Physics. The complex includes a 285 MeV linear electron accelerator, a 510 MeV linear positron accelerator, and an accumulator–cooler with beam injection and ejection channels. Intense work on the design, assembly, and tuning of the linear electron accelerator has been conducted in the last 2 yr. As a result, by August 2002 the linear electron accelerator was put into operation with all standard subsystems. By this time, the isochronous achromatic turning of the electron beam, a system for converting electrons into positrons, and the first accelerating structure of the linear positron accelerator were assembled and put into operation. All this made it possible to accelerate the positron beam up to 75 MeV. Preliminary results of tests of the linear accelerators are presented.     

中国散裂中子源加速器注入束流损失调节研究

注入系统是中国散裂中子源（CSNS）加速器的核心组成部分,对束流功率提升和稳定供束运行具有重要意义。注入束流损失是快循环同步加速器（RCS）能否在高功率下运行的决定因素之一。本文首先研究CSNS加速器注入束流损失的主要来源,包括注入参数不匹配、注入方式选择、剥离膜散射粒子损失、未被剥离的粒子损失等。其次,根据加速器的束流调节进程,对不同来源的束流损失进行调节和优化,降低注入束流损失,提高注入效率。最后,总结注入束流损失调节结果,初步测量得到注入效率约99%,并对进一步降低注入束流损失、提高注入效率提出改进方法和意见。     

350keV电子高压加速器研制

加速器辐照装置用于辐照生产医用输液塑料袋原膜材。所研制的350keV电子高压加速器具有以下特点：在静电加速器中采用高压倍压电源代替输电带，此新型结构加速器可输出低能大功率电子束，且体积小、自屏蔽，适于在线辐照加工；一般高压倍压电源采用50Hz供电，而在此装置中由14kHz中频电源供电，高压电源体积小。加速器空载高压达370kV，电子束350keV/20mA，扫描宽度70cm，辐照剂量不均匀性好于7%。该加速器辐照装置已投入运行，并已生产出合格医用输液袋膜材投放市场，产品填补了国内医用输液袋膜材市场的空白。     

多能量档电子直线加速器用栅控电子枪电源研究

本文介绍了一种应用于多能量档电子直线加速器栅控电子枪的专用电源。根据栅控电子枪的工作需求,电子枪的阴极处于-50 kV高压上,电源的3路输出,包括灯丝电源、偏压电源和栅控脉冲电源,均通过高压隔离变压器,将信号输送到高压端的灯丝、阴极和栅极上。利用主控计算机精确调节了电子枪发射束流的大小和脉冲宽度,以满足加速器多能量输出的需求。高压端均为无源器件,以降低故障率。此电源结构简单、调节方便、工作稳定,已在多能量档电子直线加速器上连续工作近4 a,运行状态良好。     

中国散裂中子源强流质子加速器设计、研制及调试运行

中国散裂中子源（CSNS）是基于强流质子加速器的大科学装置,通过高功率质子束流轰击重金属靶产生高通量中子用于开展中子散射研究,CSNS是世界上第四台、发展中国家第一台脉冲型散裂中子源。CSNS包括高功率强流质子加速器、中子靶站和中子谱仪以及相应的配套设施等。加速器由80 MeV负氢直线加速器、1.6 GeV快循环同步加速器及相应的束流输运线组成。CSNS加速器是我国第一台中高能强流高功率质子加速器,本文将介绍CSNS加速器的设计、关键技术、设备研制以及束流调试过程和其中关键问题。     

Heavy-current accelerator based on a transformer

The operating principles of a direct-action accelerator designed to acceIerate electrons to an energy of 1.5 MeV with a mean beam power of tens of kilowatts and an efficiency of around 90% are described. The electron-current pulse length can be varied from 0 to g msec, and the repetition frequency up to 50 times per sec. The mean current im may reach 1/6 of the maximum current in the pulse. Magnetic lenses are installed in order to focus electron currents of up to 100 mA into a beam a few mm in diameter in the accelerating tube. Heavy-metal screens are placed close to the axis of the tube in order to protect the gas gaps and other electrically-stressed parts of the accelerator from radiation arising inside the tube.The construction of a system for producing an electron beam with an energy of 1.5 MeV and a mean power of 25 kW (i_m = 17 mA) is described.Translated from Atomnaya Énergiya, Vol. 20, No. 5, pp. 385–392, May, 1966.     

Development of an electron linac at PNC for transmutation studies

Various methods have been examined to transmute long-lived fission products using accelerators at PNC. The present paper describes the development of a high power continuous wave (CW) electron linac which was started in 1989 to study the feasibility of nuclear waste transmutation. Transmutation by photonuclear reaction using an electron accelerator has the advantage of producing a relatively small amount of secondary radioactive waste. It is also deemed to broaden the base of accelerator technology.

The PNC high power CW electron accelerator, which is designed to accelerate energies up to 10 MeV and an average beam current of 20 mA and has a normal conducting traveling wave resonant ring (TWRR) disk-loaded accelerating tubes, was pre-commissioned with an injector and the first accelerating tube.

In December 1995, the accelerator had been partially built and the pre-commissioning of the injector began. We have been successful to produce electron beams with 3 msec pulse width, 100 mA peak, and about 2.9 MeV energy. The facility construction will be completed in March 1997, followed by the commissioning of the entire 10 MeV linac.     

Measurement of the Beam Position in the Extraction System of the ILU-10 Linear Electron Accelerator

A system for measuring beam position for a ILU-10 pulsed linear electron accelerator is described. The accelerator generates an electron beam with energy up to 5 MeV. The rf generator operates at 115 MHz in the pulsed mode with pulse duration of about 500 sec and pulse repetition frequency up to 50 Hz. The average beam power can reach 60 kW. Two electrostatic sensors (pickups) are used to measure the position of the beam. The principle of operation of the measurement apparatus is based on homodyne detection of the signals from the pickups. The second harmonic of the frequency of the accelerating voltage of the accelerator power supply (230 MHz) is chosen as the working frequency. The detected signal is fed from each pickup plate into an integrator and then a ADC. The beam position is calculated on a computer. The resulting error in the beam coordinates is about 0.5 mm with a 110 mm in diameter position sensor.     

The VEBA Relativistic Electron Accelerator

The VEBA high-current, relativistic electron accelerator has been designed and constructed at NRL for application in the study of high-power microwave sources. To meet the requirements of this study, the accelerator was designed for operation in either a short (60 nsec) or long (2.2 ?sec) pulse mode. The short-pulse mode has been in operation for nearly two years and has proven to be an extremely reliable design. The design of the long-pulse mode is now complete and component fabrication will soon be underway. The pulse-forming network in the short-pulse mode is an unbalanced, water Blumlein with an output impedance of 9.2? The Blumlein is pulse charged by a 17 stage Marx generator which has a series capacitance of 29.4 nF. By transmission along a tapered coaxial line, the output pulse is transformed to 20 ? and the voltage developed across a matched load increased to a maximum of 2.5 MV. The proposed conversion to the long-pulse mode will require that the Blumlein and transformer sections be removed and the diode assembly be attached directly to the oversized Marx tank. The direct coupling between the Marx and the Blumlein will then be replaced by two, nested, water capacitors which are shunted by spiral inductors. When coupled in series with the Marx, this output filter will form a three-section, voltage-fed, Guillemin (type A), pulse-forming network with a characteristic impedance of 40 ? and a maximum output voltage of 0.9 MV.     

基于电子直线加速器的空间电子环境地面模拟用电子源设计与实现

空间电子环境地面模拟装置由1台电子直线加速器提供能量1~5 MeV范围内的电子,后续束流传输系统将电子束进行扩束处理。较大的能量范围对加速器的设计与运行条件提出了较高要求。本文主要阐述了该加速器的设计与实现过程,综合考虑了能量开关技术和束流负载效应,通过研究不同条件下的耦合度参数特性确定了加速管耦合度,分析提出了磁控管输出参数并进行了实验研究。加速器实验测试结果表明,电子束能量参数达到指标要求,为模拟装置提供了有效可靠的电子源。     

Nuclotron: Basic Results and Development Plans

The results of the development and operation of the accelerator complex at the high-energy laboratory of the Joint Institute of Nuclear Research, a nuclotron – the first rapid-cycling superconducting synchrotron – being the main component, are described. The accelerator was developed on the basis of a unique technology for building superconducting magnets which are capable of operating with a cycle repetition frequency up to 1 Hz.Among the latest results, it is mentioned that the energy consumption for operation of the accelerator is substantially decreased and the duration of continuous operation is increased. The beam extraction system recently put into operation is described. For the first time, this system is based on components which operate at low temperature (about 4.5 K). Data on the upgrading of the ion sources are presented.Plans for further development of the accelerator complex are described: production of intense beams of polarized deuterons, application of superconducting magnets in the beam channels, and development of a superconducting nuclotron booster.     

DG系列大功率工业辐照电子加速器

中国科学院近代物理研究所成功研制了DG系列中频变压器型工业电子加速器,其中DG-2.5型加速器能量范围1.0-2.5 MeV,最大束流功率90 kw,束流扫描有效宽度1000 mm,适用于各种辐照领域;DG-1.2型能量范围0.8-1.2 MeV,最大功率50 kw;这两种型号加速器均通过了长时间测试,工作稳定、故障率低,采用计算机自动控制,并可与束下传动系统连锁,完全达到了工业应用的标准.     

基于IOT放大器的微波功率源在超导直线加速器上的应用

中国工程物理研究院太赫兹自由电子激光装置（CTFEL）的直线加速器由两个4-cell超导加速腔构成,每个加速腔的激励由1套基于感应输出管（IOT）放大器的L波段微波功率源（25 kW）提供。本文介绍了微波功率源的基本原理、组成结构和调试过程,以及微波功率源在功率耦合器老炼平台和超导直线加速器上的一些实验结果。微波功率源安装调试后工作稳定,两套微波功率源的主要参数均达到设计要求。超导直线加速器的幅值稳定度和相位稳定度分别为0.04%和0.08°,优于设计指标。     

DZ-12/4多能量档电子直线加速器辐照关键参数测试

中国原子能科学研究院建立了一台DZ-12/4多能量档电子直线加速器,该装置主要用作辐射加工级电子束辐照实验平台。为了检测该电子束辐照实验平台辐照工艺控制参数,本文利用中国原子能科学研究院FJL-02型辐射变色薄膜剂量计对DZ-12/4多能量档电子直线加速器关键参数能量进行了测量,并对研制的束流监测系统法拉第筒的可靠性进行了验证。结果表明,DZ-12/4多能量档电子直线加速器能量在4~12 MeV范围可调,运行参数准确可靠;日常运行中,加速器运行人员通过监测设备和调节加速器参数可有效控制并估计辐照剂量,具有非常好的实用性和简便性。     

Analysis of X-ray spectra in 14.5-GHz ECR ion source for optimizing operation conditions

An electron cyclotron resonance (ECR) ion source operating at 14.5 GHz was developed for the generation of charged ions at the Korea Atomic Energy Research Institute (KAERI). Experiments were carried out to study the plasma inside the ECR ion source by analyzing the X-ray spectra generated by it. The X-ray energy distribution and electron energy inside the plasma chamber are influenced by the status of the heated plasma. That status depends on various operation parameters such as microwave power, injected gas-pressure, and solenoid and trim coil currents. X-ray spectra were recorded to find the correlation between the plasma and the X-rays for variations in the operation parameters. A standard NaI(Tl) detector was used for that purpose. The X-ray energy distribution was studied in the range of 100–500 W for radiofrequency power. The influence of the injected gas pressure and the mirror ratio in the emission of X-rays were analyzed.     

Dose-voltage dependence of coaxial Bremsstrahlung diodes

The relation ∝ IV^2.65 is widely used to estimate the on-axis radiation-dose rate for flash X-ray sources, as a function of diode current, I, and voltage, V, 1 m downstream of an optimized bremsstrahlung target. This relation is valid only for pencil beams. In this paper, we show that for diodes having beams with finite spatial and angular extent, this relation can still be used if the power 2.65 is modified. Using particle-in-cell and radiation-transport codes, this modification is evaluated for a diode proposed for the 20-MeV HERMES III accelerator that is currently under construction. Predictions of the calculational model are compared with measurements obtained from experiments on the existing 3-MeV HELIA accelerator and are found to be in good agreement. These results are characteristic of finite-area coaxial diodes in general and show the trend of the deviation from 2.65 for such sources.     

核电建安工程辐射安全风险分析及管理实践

建立了核电工程施工领域射线探伤辐射安全故障树模型,采用故障树分析方法全面分析了射线探伤作业过程中发生辐射安全事件的风险。结合我国辐射防护相关法律、法规和标准的具体要求,参考Bechtel和FA3等公司的做法,按照作业工艺流程,制定了一套完整的核电施工现场射线探伤控制措施,从管理制度上和技术手段上杜绝安全事件的发生,规范核电工程施工领域射线探伤的辐射安全防护管理。