数字化I/Q技术用于磁控管频率控制

采用磁控管做功率源的低能电子直线加速器在医疗、辐照、X射线检测等领域得到较为广泛的应用。磁控管产生的微波信号输入到加速管,对电子束进行加速,磁控管的工作频率稳定性对加速器电子束能量、能散及发射度产生直接的影响。但磁控管是一种振荡器,其频率受到温度、振动、负载牵引的影响会产生漂移,所以需要一套自动频率控制系统(Automatic Frequency Control,AFC)机构对磁控管进行频率控制。目前普遍采用的AFC机构主要是行波控相或双腔鉴频,对两路检波信号差分放大进而控制伺服电机进行调谐的方法实现磁控管的频率稳定。随着数字化I/Q和FPGA(Field-Programmable Gate Array)技术的不断发展,运用该技术进行磁控管的频率控制完全具备可行性。本文从理论和工程设计上阐述了数字化I/Q技术在磁控管频率控制上的应用。     

探伤加速器用磁控管自动调谐调整机构的研制

探伤加速器的剂量率稳定性是反映加速器整体性能的重要指标。剂量率的稳定涉及的因素较多，运行中磁控管与加速管频率的匹配是主要因素。通过磁控管的调谐机构，调整其频率以适应加速管的频率变化是稳定剂量率的一个重要手段。磁控管自动调谐机构采用步进电机驱动磁控管调谐旋钮，采用编码器纪录调谐旋钮的位置，通过位置估算磁控管的频率。     

6 MeV无损探伤电子直线加速器微波系统研制

微波系统是无损探伤电子直线加速器的重要组成部件之一。它包括微波的产生、传输、监测以及保证系统稳定工作的充气装置和自动频率控制装置。 MG5193型磁控管工作频率2998MHz,输出脉冲功率2.6MW,平均功率2.6kW,经过方圆转     

9MeV无损探伤电子直线加速器微波系统研制

微波系统是无损探伤加速器的重要部件之一,它产生频率2 998 MHz、脉冲功率2.6 MW的射频信号,并经传输波导馈入加速管,在加速管内形成驻波电磁场,加速电子到能量9 MeV。 为了保证磁控管稳定工作和运行,采用高功率四端环行器隔离加速管的反射,采用紧凑型定向耦合器分别对入射与反射的射频信号取样,监测功率电平、频率与微波包络波形,同时为自动频率控制装置提供鉴相信号,使磁控管工作频率自动跟踪加速管的谐振频率,从而获得稳定的能量与最大剂量率输出。波导系统充入0.18 MPa的六氟化硫,防止射频电击穿,提高系统运行的稳定性。该系统提供…     

驻波型电子直线加速器自动频率控制的改造

驻波型电子直线加速器采用鉴相式技术实现加速管、磁控管的频率跟踪控制。当加速器出束运行时,加速管、磁控管的温度发生变化,导致二者的频率变化,必须对磁控管进行频率调整,若频率差太大,导致功率不能很好馈入加速管,甚至造成全反射,长时间可能会损坏磁控管等设备。改     

基于PLC自动搜频AFC系统研究

自动频率控制（AFC）系统是电子直线加速器关键系统之一,由于磁控管强烈的频率突变或温度对它的影响极易造成磁控管频率偏移,导致AFC系统失效,并使加速器剂量率急剧下降。为克服现有AFC系统存在的问题,本工作根据磁控管调谐位置和剂量率反馈信号研究设计具有自动搜频功能的AFC系统。实验结果表明,该系统可有效防止频率偏移,维持加速器最大剂量率输出。     

行波电子直线加速器稳频系统的鉴频方法

稳频系统的频率稳定度取决于谐振腔体的有载品质因素。因电子直线加速器的功率源是脉冲磁控管，其功率谱为形状，无限增大品质因素是不正确的，由帕息维尔定理知道腔体平方律检波器输出信号的面积正比于腔体输出能量，于是当磁控管振荡频率改变时，该信号面积的变化等效于腔体输出能量的变化，根据上述原理获得了品质因素的上限和推荐表达式。     

NDZ 20 医用电子直线加速器的设计.运行和临床疗效

NDZ20医用电子直线加速器,属行波反馈型,采用改变工作频率、相位、磁控管输出功率及束流负载的方法调整能量,电子线能量从5—20MeV分七档,X线有10、15MV两档,并设有AFC,ARC,ADC等自动稳定频率、剂量率和照射野均匀度等控制系统,对一些主要部件达到较为先进的指标。该机运行已近两年,停机率86年与87年分别为2.14%和3.53%,剂量稳定性等一系列指标均达到或优于国家GBW4-81所规定指标,两年来治疗病人1366人,疗效显著。     

2MeV行波电子直线加速器自动频率控制系统

在电子直线加速器中,微波功率源输出频率的稳定性非常重要,它直接影响到加速器整机的物理性能指标。由于微波功率源磁控管的输出频率会随外部工作环境变化而发生漂移,所以必需在电子直线加速器中采用自动频率控制(AFC)系统。讨论了2MeV小型行波电子直线加速器AFC系统的设计要素,分析了微波信号的鉴频原理及鉴频模块的测试结果。结合实际的工作环境,测试了信号处理单元主要功能模块的输出,并对测量结果的精度进行了分析。     

新型驻波加速器用恒温水冷系统的研制

驻波加速器系统中需要恒温水冷系统冷却。恒温的部件有加速管管体、靶、微波窗、磁控管、四端环流器、三端负载等。恒温水冷系统主要为加速管和微波系统提供循环冷却水，以保持磁控管的频率跟踪加速管的频率并冷却微波系统的元件。恒温水冷系统分为循环水系统及制冷系统，根据安装位置及环境，可选分体式或一体式。     

An accelerator operator's companion for the McMaster UniversityModel FN tandem accelerator

A prototype accelerator operator's companion was developed to investigate the feasibility of automating the operation of the McMaster University Model FN Van De Graaff accelerator. Its purpose is to provide the accelerator staff with a working model with which they can experiment and which would motivate discussions to further pinpoint their needs. Initial needs and goals were established at the outset of this project and, on the whole, were met with this first version of the software system. As presently constituted, the operator's companion functionally provides an electronic log book system that stores all the operating parameters, a procedures system that presents the operating procedures with the appropriate operating parameters embedded in them at display time, and a diagnostic system that is able to diagnose problems associated with the accelerator when utilizing information from the log book and input from the user. Through discussions with the accelerator staff at various stages throughout the development and at the final evaluation, important feedback was generated, which helped to define operational needs further     

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.     

A Comparison of Triodes and Klystrons for Particle Accelerator Applications

In the frequency range between 200 and 1200 mcs, it is possible to use either klystrons or triodes for particle accelerator applications. This paper analyzes the bases of choice between these tube types from a systems point of view. It treats development status, initial and operating costs, reliability, system complexity, and all pertinent technical factors. The tentative specifications of the proton linear accelerator r-f system proposed by Los Alamos are used as a basis for comparison, and the conclusions reached on this system are extrapolated to higher and lower frequencies. It is concluded that either triodes or klystrons can be used in most, if not all, applications and that in almost every significant respect, in the frequency range considered, the klystron system is superior to the triode system.     

High Energy Electron Accelerators

The Cambridge Electron Accelerator is now in full-scale operation for research at energies up to 6 Bev, five times higher than earlier electron accelerators. The machine, a synchrotron, uses a ring of 48 alternating gradient magnets in a circle 236 feet in diameter. Electrons are accelerated by RF fields produced in a set of sixteen resonant cavities spaced around the orbit. The frequency used is 476 Mc/s, the 360th harmonic of the orbital frequency. Injection of 30-Mev electrons is accomplished by using a linear accelerator operating at 2855 Mc/s. The main machine accepts and-accelerates to maximum energy beam currents of up to 1.2 x 1012 electrons/sec. The quality of the beam is fully as good as that from a linear accelerator. The CEA laboratory operates five days a week on a three-shift basis and has a staff of 160 people.     

Upgrade of the Slow-Extraction System in the U-70 Proton Accelerator

The purpose of this work was to increase the efficiency of slow extraction of accelerated protons from the U-70 accelerator in order to provide the extracted beam for a physical setup requiring high intensity. On account of the limited power of the first extraction setup – an electrostatic deflector, the angle spread of the beam near the deflector barrier had to be decreased in order to decrease the losses and increase the efficiency. For this, the structure function was increased by inserting two additional quadrupole lenses into the magnetic structure of the accelerator. As a result of the inadequate strength of the system which corrects the frequencies of the betatron oscillations at the maximum accelerator energy 70 GeV, the beam was extracted at energy 64 GeV, where the frequency of the vertical betatron oscillations could be set above the line of the resonance 4Q _z = 39. As a result, the losses at the first two extraction setups increased by a factor of 3 and the efficiency of the slow-ejection system increased from 85% to 95%.     

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.     

3 GHz Superconducting Accelerator Cavity for Use in an Electron Synchrotron

Experience has shown that superconducting accelerator cavity performance improves as the operating frequency rises. To use this effect to advantage in an electron synchrotron one must develop cavities of aperture large enough to provide the necessary phase space admittance and of such a configuration as to avoid problems with lost particles and synchrotron radiation in the orbit plane. The development of such a cavity, open in the mid-plane, is described and test results given.     

高能电子单粒子效应模拟实验研究

本文基于2 MeV自屏蔽电子加速器和10 MeV电子直线加速器,开展了电子单粒子效应实验研究,并分析了其机理。在保持入射电子能量不变的情况下,在±20%范围内改变器件的工作电压进行了单粒子翻转实验。实验结果表明：45 nm SRAM（额定工作电压1.5 V）芯片在电子直线加速器产生的高能电子照射下能产生明显的单粒子翻转,单粒子翻转截面随入射电子能量的变化趋势与文献数据相符合;电子引起的单粒子翻转截面随器件工作电压的变化趋势与理论预期一致,即工作电压越小,单粒子翻转临界电荷越小,翻转截面也越高。     

Secondary and activated X(γ) radiation of SPHIC particle therapy facility

We report the secondary X(γ) radiation from the accelerator in a normal operating state and activated X(γ) radiation from the accelerator devices when the accel...     

Gas flow and related beam losses in the ITER neutral beam injector

The gas flow in the ITER neutral beam injectors has been studied using a 3D Monte Carlo code to define a number of key parameters affecting the design and operation of the injector. This paper presents the results of calculations of the gas density in the two accelerator concepts presently considered as options for the ITER injectors, and the resultant stripping losses of the negative ions during their acceleration to 1 MeV. The sensitivity of the model to various parameters has been studied, including the gas temperature in the ion source and the subsequent accommodation by collisions with the accelerator structure, and the degree of dissociation of the D₂ or H₂ in the ion source, and subsequent recombination during collisions with the accelerator structure. Additionally the sensitivity of the losses to details of the beam source design and operating parameters are examined for both accelerator concepts.