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.     

Basic information on new regulatory criteria requiring on-site emergency preparedness for accelerator facilities in Japan

For basic information on new regulatory criteria, the dose rate around a thick target bombarded by proton, electron, or carbon beam having incident energy of 10 MeV–50 GeV (per nucleon in case of carbon) was simulated using the PHITS Monte Carlo code. Based on this simulation, the benchmark which is ‘1 Sv/h at 1 m away from the beam line’ assuming 1% beam loss was evaluated, and compared with the criteria in France and Canada. Based on this evaluation, a new regulatory criteria has been established for requiring on-site emergency preparedness for accelerator facilities in Japan, which is required for the ion accelerator beyond the ion beam of 100 MeV/nucleon and 0.5 kW beam power, and the electron accelerator beyond the electron beam of 50 MeV energy and 1 kW beam power.     

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.     

Preliminary evaluation of beam dump for high current electron beam at JNC

A high current electron beam is required for transmuting fission products using gamma rays. Elemental technology for a linac that generates a high current beam in an efficient and stable manner is being developed at Japan Nuclear Cycle Development Institute (JNC). A beam dump for the high current, low energy electron beam (20 mA, 10 MeV) from this accelerator has been constructed and tested at JNC. A Ring and Disk (RD) structure was adopted to absorb the beam safely and to analyze the beam condition in real time. The thermal and stress analysis showed that a 200 kW electron beam could be securely stopped. The performance of the beam dump was evaluated using a beam of 7.0 MeV and an average current of 0.84 mA. The measured results showed that the electrons transported from the accelerator were completely absorbed. The temperature rise of the plates and the 1 cm dose equivalent rate of bremsstrahlung photons were consistent with the simulation data. In addition, the beam dump was found to be capable of monitoring the beam condition directly from the temperature distributions and peak current.     

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。     

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.     

工业电子辐照加工及加速器性能检测

本文简要介绍了电子辐射加工技术的主要特点以及中国科学院高能物理研究所10MeV/15kW辐照加速器的主要性能。给出了能量、流强、扫描均匀性、扫描长度以及束斑形状等5个重要参数的测量方法及结果。      

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。     

Target optimization for a 10-MeV E-beam neutron converter

Accelerator-based target design and optimization is an approach for neutron generation. The target plays an important role for a neutron source on an electron accelerator. For optimizing a neutron source using 10 MeV electron beams of Rhodotron-TT200, Pb, Ta, or W alloys with Be were calculated as photo-neutron converter. The neutron yield, flux and energy were simulated using the MCNPX code. The results indicate that a 10 MeV electron beam is capable of producing high-intensity neutron flux of 1013n·cm–2·s–1 with average energy of 0.8 MeV.     

Induced Activity of a Tungsten Target in a 10 MeV Electron Accelerator

Experiments are performed to determine the isotopic composition of the induced activity of a tungsten target for a 10 MeV electron beam. The measurement results are used to calculate the dose rate from the induced activity of the target for an accelerator with 100 kW beam power. It is established that ¹⁸⁷W radiation makes a substantial contribution to the dose rate. The neutron yield from the target and the flux density of neutrons scattered in the accelerator room are estimated.     

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.     

高平均束流功率辐照加速器加速结构的研究

本文介绍了10 MeV/100 kW的高平均束流功率工业辐照加速器束流动力学模拟结果及其加速结构的优化设计结果。加速器采用驻波双周期轴耦合结构,1个加速腔和1个耦合腔构成1个加速单元,其工作频率为325 MHz,工作模式为π/2,加速腔和耦合腔之间通过耦合狭缝在轴向以磁耦合的方式耦合在一起。使用SUPERFISH优化加速腔的有效分路阻抗、Kilp系数等关键参数。束流动力学方面,使用PARMELA模拟论证在粒子源提供2.5 keV、500 mA的电子束后,通过6个加速腔可得到10 MeV/100 kW的平均束流功率。加速腔优化完成后使用CST对耦合腔进行了设计,此时由6个加速单元组成的加速结构有效分路阻抗为23.9 MΩ/m、无载品质因数为29 347,各加速腔与相邻的耦合腔耦合系数为4.7%,工作模式与其相邻模式的最小频率间隔为2 MHz,每个加速单元功耗为290 kW。     

在电子驻波直线加速器上获得小束斑电子束

近年来高效率探测器阵列数字辐射照相技术已经用于无损探伤实时在线图象处理检测。厚在则重的关键部位的微小缺陷，需要用加速器产生的高能电子束作为焦点打靶产生Ｘ射线进行无损探伤检测。     

Race-Track Microtron–Recirculator with Superconducting RF Cavities

The importance of designing and building a modern continuous electron beam accelerator for medium energy and possible directions for the design and implementation of the basic systems of such an accelerator are examined. Substantiation is given for the type of accelerator – a race-track microtorn with energy up to 200 MeV using superconducting accelerating cavities operating at liquid-helium temperature. A novel scheme is proposed for the microtron–recirculator. In this scheme, recirculation with individual deflection and focusing systems is orgnized for the first few orbits; further acceleration occurs in a standard microtron regime.     

Depth Smoothing of the Dose under Irradiation by Electrons

Irradiation uniformity is an important problem in radiation technology employing electron beams. One variant of a solution of this problem is the use of filters partially covering the primary beam. A method for optimizing the filter parameters is presented; the method used is the modern certified code package PENELOPE. The influence of filter material on the radiation utilization coefficient of a linear electron accelerator is investigated. For processing of polyethylene with a 6 MeV electron beam, filter parameters giving a high uniformity of the depth distribution of the absorbed dose in the material are obtained.     

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.     

大型工业电子束脱硫脱硝装置辐射等效剂量场模拟与系统参数优化

为优化大型工业电子束脱硫脱硝装置和配套大功率电子加速器工程参数,应用Geant4模拟分析了不同出射能量的单能电子束在烟气中的径迹和偏转后电子束在烟气中的等效剂量场。计算得到1.75 MeV电子束更符合1 000 MWe级火电机组烟气系统工程设计需要,计算结果将为工业化设计提供参考。     

一台2.5MeV电子辐照加速器系统的屏蔽

介绍了一台能量2．5MeV、流强40mA、功率100kW的电子辐照加速器系统的屏蔽设计。实际测量结果表明：屏蔽外的辐射水平低于国家标准规定的限值,设计是合理的。