射频反馈电子直线加速器的稳态特性

本文讨论了含聚束器的射频反馈电子直线加速器基于耗散方程的稳态束负载理论,导出了加速器稳态特性的解析关系,最后计算了桥比n=1和n=n_(opt)加速器的负载特性。     

Alternative of RF System Design for CYCIAE-100 Project

The RF system is a key part of the 100 MeV cyclotron in the upgrade project of HI-13 tandem accelerator, which includes RF generators, resonant cavities, transmission components, power supply and water cooling devices, computer control, and so on.     

70 MHz回旋加速器谐振腔高频性能的数值研究

介绍了用数值模拟手段设计加速腔体的方法。在设计70MHz回旋加速器谐振腔的过程中，为满足回旋加速器磁铁的结构要求，对高频频率、Q值等高频参数进行了研究。在设计阶段，应用基于有限元方法的程序对高频实验进行模拟计算。回旋加速器腔体的初步设计结果将用于最终物理设计和工程设计。     

铁氧体定向耦合器及其在加速器高频控制中的应用

设计了一种６ＭＨｚ、３ｄＢ铁氧体定向耦合器，并用于制作加速器高频系统的控制单元。此种定向耦合器是用紧密绞合的双股漆包线绕在射频铁氧体磁环或磁芯上做成，具有尺寸小、结构简单和频带宽等优点，工作范围一般在几个ＭＨｚ到几十个ＭＨｚ。在此基础上设计制作了鉴相器、反设式电调移相器、电调衰减器和ＡＬＣ等线路，使加速器高频谐振腔实现了自动调谐。     

高频单腔加速器的束流动力学和数值计算

文章介绍的束流动力学与高频谐振腔数值计算相结合的方法,可以简化常规束流动力学计算,也为谐振腔的优选提供了重要的判断标准。同时给出了将此方法用于高频单谐振腔加速器设计时所得到的一些主要结果。     

Studies on the Matching Network of the High Power Radio Frequency Transmitter for the NBI RF Ion Source

A radio frequency (RF) driven ion source has been developed at ASIPP (Institute of Plasma Physics, CAS) for the neutral beam injector with a 1 MHz, 25 kW RF power supply system. The paper describes the studies performed with emphasis on the RF matching network system design based on the dedicated Smith chart analyses to improve and simplify the optimized solution. Also the future RF matching network design was analyzed with the matching transformers which were set between the high-power RF transmitter and the RF driven ion source to isolate the high voltage from the accelerator of the ion source.     

230 MeV超导回旋加速器高频低电平系统设计与桌面实验研究

中国原子能科学研究院正在研发一台230 MeV医用超导回旋加速器,用于天津肿瘤医院的质子治疗项目。为满足加速器高频系统的腔体负载Dee电压稳定度、高频频率稳定度及加速电压幅度平衡度的要求,本文研制一套包含模拟数字混合型幅度环、数字型调谐环和数字型电压平衡环3个环路的低电平控制系统。该低电平系统通过串口与上位机进行通信,以实现本地调试;利用Profibus-DP通信协议,实现低电平系统和PLC组网的交互通信。在1个缩比例无氧铜实验腔体上完成了低电平系统低功率桌面实验与联合调试,验证了电压调平衡算法的有效性,并实现了低电平控制系统的一键启动,无需人工干预,满足了加速器高频系统对低电平控制系统的需求。     

用于2 GeV固定场交变梯度质子加速器的高品质因数、高分路阻抗波导型高频腔设计

在核工业、民用及基础研究领域，高能强流质子加速器有着十分广泛而重要的应用，中国原子能科学研究院提出了1台2 GeV连续波固定场交变梯度质子加速器的解决方案。在该方案中，工作在44.4 MHz的大功率高品质因数、高分路阻抗波导型高频腔研制极其重要。本文首先对工作在44.4 MHz的矩形、欧米伽形、跑道形及船形等4种形状的波导型高频腔进行了模拟计算研究，经比较发现，船形高频腔具有最高的品质因数和分路阻抗，是2 GeV连续波固定场交变梯度质子加速器的较好选择。在此基础上，为掌握船形高频腔的实际加工工艺，同时利用现有230 MeV超导回旋加速器的功率源设备开展高功率实验研究，设计了71.26 MHz的缩比例船形高频腔样机。     

Design of the Prototype Negative Ion Source for Neutral Beam Injector at ASIPP

In order to support the design,manufacture and commissioning of the negativeion-based neutral beam injection(NBI) system for the Chinese Fusion Engineering Test Reactor(CFETR),the Hefei utility negative ion test equipment with RF source(HUNTER) was proposed at ASIPP.A prototype negative ion source will be developed at first.The main bodies of plasma source and accelerator of the prototype negative ion source are similar to that of the ion source for EAST-NBI.But instead of the filament-arc driver,an RF driver is adopted for the prototype negative ion source to fulfill the requirement of long pulse operation.A cesium seeding system and a magnetic filter are added for enhancing the negative ion density near the plasma grid and minimizing co-extracted electrons.Besides,an ITER-like extraction system is applied inside the accelerator,where the negative ion beam is extracted and accelerated up to 50 kV.     

600kV强流毫微秒脉冲加速器中的前切割与后聚束系统

介绍了６００ｋＶ强流微秒脉冲加速器中束流脉冲化系统的物理设计、工艺结构特点、粒子动力学计算、聚束腔的静态特性调整与测量、高频功率发射系统以及载束实验结果。     

用于回旋加速器射频低电平系统的通用DSP固件程序设计

针对回旋加速器射频系统幅度、相位、启动逻辑、联锁保护、在线参数修改等控制需求,编写了一种基于有限状态机的通用DSP固件程序。该固件程序将射频系统启动过程划分为5个状态:封锁RF信号、搜索腔体谐振点、提升射频功率、匹配相位、幅相闭环控制。该固件程序通过串口与本地上位机和远程控制机进行实时通信,支持在线修改射频系统启动参数;采用异步事件驱动方式,实现对打火和反射功率过大等异常情况快速响应。该固件程序成功应用于CYCIAE-100回旋加速器射频低电平系统中,在CYCIAE-100回旋加速器调束过程中,完成了射频系统的启动控制和设备保护,满足加速器控制系统的需求。     

First results of negative ion extraction with Cs for CRAFT prototype negative beam source

In order to understand the physics and pre-study the engineering issues for radio frequency(RF)negative beam source, a prototype source with a single driver and three-electrode accelerator was developed. Recently, the beam source was tested on the RF source test facility with RF plasma generation, negative ion production and extraction. A magnetic filter system and a Cs injection system were employed to enhance the negative ion production. As a result, a long pulse of 105 s negative ion beam with current density of 153 A m-2 was repeatedly extracted successfully. The source pressure is 0.6 Pa and the ratio of co-extracted electron and negative ion current is around0.3. The details of design and experimental results of beam source were shown in this letter.     

脉冲高频加速器束流动力学计算

用增补后的Parmela程序模拟了脉冲高频加速器中粒子的三维运动,给出了粒子在各相平面上的发射度大小和图示,同时简述了谐振腔的载束性能,并讨论了螺线管里束流横向发射度的变化。     

EPICS based low-level radio frequency control system in LIPAc

The IFMIF–EVEDA (International Fusion Materials Irradiation Facility – Engineering Validation and Engineering Design Activity) linear accelerator, known as Linear IFMIF Prototype Accelerator (LIPAc), will be a 9 MeV, 125 mA continuous wave (CW) deuteron accelerator prototype to validate the technical options of the accelerator design for IFMIF. The primary mission of such facility is to test and verify materials performance when subjected to extensive neutron irradiation of the type encountered in a fusion reactor to prepare for the design, construction, licensing and safe operation of a fusion demonstration reactor (DEMO). The radio frequency (RF) power system of IFMIF–EVEDA consists of 18 RF chains working at 175 MHz with three amplification stages each. The low-level radio frequency (LLRF) controls the amplitude and phase of the signal to be synchronized with the beam and it also controls the resonance frequency of the cavities. The system is based on a commercial compact peripheral component interconnect (cPCI) field programmable gate array (FPGA) board, provided by Lyrtech and controlled by a Windows host PC. For this purpose, it is mandatory to communicate the cPCI FPGA board from EPICS Channel Access [1]. A software architecture on EPICS framework in order to control and monitor the LLRF system is presented.     

Hefei utility negative ions test equipment with RF source: commissioning and first results

In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). Its negative ion source can be equipped with single or double RF drivers. There is a plasma expansion chamber with depth of 19 mm and an enhanced filter field. A three electrodes negative ion accelerator was employed to extract and accelerate the negative ions, which are plasma grid, extraction grid and ground grid. And there are several diagnostic tools for the plasma and beam parameters measurement. The characteristics of plasma generation, negative ion production and extraction were studied on the test equipment. The negative ion beam was extracted from the RF driven negative ion source for the first time. The detailed structure and main results are presented in this article.     

基于冗余技术的强流质子RFQ控制系统设计

中国科学院近代物理研究所研制了一台用于ADS注入器Ⅱ的强流质子RFQ加速器。相对于常规功率源,用于RFQ腔体的功率源的控制精度要求更高、过程更复杂。控制系统需通过精确的水温控制实现频率调谐,水温的控制和监测精度要求为0.1 ℃。同时,为避免腔体因局部温度过高而损毁,控制系统必须实现实时的温度监测和可靠的联锁保护功能。为此,基于EPICS控制架构设计了RFQ控制系统,对关键控制代码的运行平台采用高性能冗余控制器,开发了具有网络冗余功能的IOC驱动程序,实现了水温联锁保护及高频系统控制。RFQ控制系统经现场测试,通信正常、运行稳定,冗余系统的主备切换时间在ms量级,满足RFQ腔体的控制要求。     

CSNS/RCS中主要阻抗元件的仿真计算研究

中国散裂中子源（CSNS）快循环同步加速器（RCS）是强流质子加速器,对环中真空元件的阻抗研究是判断束流能否稳定运行的重要依据。通过正确估算环中元件阻抗,可及时对元件的阻抗进行有效控制和防止束流不稳定性发生,从而减小束流损失。本文利用CST电磁场仿真软件给出了RCS环中高频腔及准直器的耦合阻抗,并探讨了bus-bar结构对高频腔本身及束流稳定的影响,发现需重新设计bus-bar结构使腔固有频率大于10 MHz才能彻底解决因共振可能引起的丢束。此外,计算表明,主准直器屏蔽有利于减小耦合阻抗及损失功率,在安装代价较小的情况下需对主准直器进行屏蔽。     

中国散裂中子源直线加速器高功率自动老炼平台研制

本文研制了中国散裂中子源(CSNS)直线加速器高功率自动老炼平台,该平台集成了驻波比保护、真空检测、弧光打火探测器、腔体谐振频率计算和变频等功能,可根据腔体的打火情况自适应调节功率进行腔体老炼,通过软件界面对相关参数进行修改即可适应不同腔体的需求。该平台具有高安全性、高智能化、灵活性强的特点,其已在CSNS直线加速器8套功率源系统上使用,在保证腔体和功率源安全的前提下,大幅提高了老炼效率和降低值班人员的劳动量。     

Progress of the RF negative hydrogen ion source for fusion at HUST

Huazhong University of Science and Technology has developed an experimental setup of a radio frequency (RF) driven negative hydrogen ion source, to investigate the physics of production and extraction of the H− ions for neutral beam injection in nuclear fusion reactors. The main design parameters of the ion source are: RF power ≤40 kW; extraction voltage ≤10 kV; accelerator voltage ≤20 kV. This paper gives an overview of the progress of the ion source with particular emphasis on some issues. The RF driver and source plasma are analyzed and optimized in terms of impedance matching, plasma characteristics and power coupling. In regard to the simulation analysis, a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion source. Furthermore, a collisional radiative model of H and H2 is built for plasma optical diagnosis.     

Laser-RF synchronization based on digital phase detector

Laser oscillator synchronization with RF reference signal is ultra-important for a modem light source based on the accelerator.For Tsinghua Thomson scattering X-ray source,we have synchronized the mode-locked laser oscillator to RF reference signal with 48.2 fs RMS relative jitter.Both fundamental and harmonic signals derived from photo diode detection are used for laser-RF synchronization in our scheme.The fundamental signal is for coarse laser-RF synchronization and multiple laser oscillator synchronization.The harmonic signal is for high precise phase locking.The digital phase detector is implemented in the synchronization scheme for less noise,replacing the mixing to DC phase detection scheme.The digital processing algorithm for synchronization is commonly used in low-level RF control field.In order to test the phase locking loop logic without damaging the real laser oscillator,a laser oscillator emulator was developed for phase locking.This paper will report the laser-RF synchronization scheme and its performance.The laser oscillator emulator system will also be introduced here.