中国加速器驱动次临界系统主加速器初步物理设计

中国加速器驱动次临界系统（C-ADS）计划采用一个平均流强为10 mA的连续波质子加速器作为次临界堆的驱动器,驱动加速器的束流功率为15 MW,最终能量1.5 GeV,其中主加速器是驱动加速器的一个重要部分,完成束流能量从10 MeV到1.5 GeV的加速,所有加速腔均采用超导结构。为了避免频繁束流中断对反应堆的损坏,设计要求驱动加速器在运行过程中束流可以中断的次数非常有限,因此加速器在设计过程植入了容错机制,尝试了各种可能的方法以最大程度地满足C-ADS加速器的高可靠性和稳定性的要求。介绍了C-ADS主加速器的基本设计: 总长度306.4 m, 束流的归一化RMS发射度增长控制在5%以内。总结了各个重要参数选择过程中的考虑以及整个加速段多粒子跟踪模拟的束流动力学结果。     

中国加速器驱动系统的中能传输线-2设计

中能传输线-2（MEBT2）在中国加速器驱动次临界系统（CADS）1.5 GeV加速器的前端具有非常重要的作用。介绍了MEBT2设计思路和束流动力学分析。MEBT2的设计和模拟均使用多粒子跟踪程序TraceWin完成。给出了可以完成束流传输和匹配的消色散MEBT2设计方案。模拟结果显示:在经过此方案所设计的MEBT2后,束流横向和纵向的发射度分别有5%和13%的增长,在此系统可接受的发射度增长范围内。     

中国加速器驱动系统的中能传输线-2设计

中能传输线-2（MEBT2）在中国加速器驱动次临界系统（CADS）1.5 GeV加速器的前端具有非常重要的作用。介绍了MEBT2设计思路和束流动力学分析。MEBT2的设计和模拟均使用多粒子跟踪程序TraceWin完成。给出了可以完成束流传输和匹配的消色散MEBT2设计方案。模拟结果显示:在经过此方案所设计的MEBT2后，束流横向和纵向的发射度分别有5%和13%的增长，在此系统可接受的发射度增长范围内。     

加速器驱动次临界系统注入器Ⅰ束测系统（英）

加速器驱动次临界系统注入器Ⅰ,包括ECR离子源、低能传输线、射频四极加速单元、中能传输段和超导腔,注入器Ⅰ出口能够获得能量10 MeV的强流质子束流。为了调束和运行的需要,注入器Ⅰ将安装束流位置测量、束流截面测量、束流流强测量、束流发射度和能量测量,以及束流损失测量等束流参数测量装置。介绍了这些束流测量系统设计及其他方面的一些考虑。     

质子直线加速器设计研究

当前质子直线加速器发展的两个重要方向是强流质子直线加速器和小型质子直线加速器.前者主要用于核能领域,后者主要用于质子治疗.两类加速器有着共同的特点:1.采用一些新型加速结构,它们是传统结构的组合和发展;2.加速小发射度的质子束;3.加速器应有高度的可靠性.但前者的建造难度远大于后者,它还要求具有很低的束流损失率和尽可能高的能量利用效率.研究了两类加速器设计中的一些重要问题,提出了一些设计方案.     

消毒灭菌用电子直线加速器物理设计

介绍了杀灭邮件中携带炭疽菌用2MeV电子直线加速器的物理设计过程, 其中包括加速结构设计和束流动力学的计算:加速结构基本参数、纵向相运动、能量增长情况以及束流能谱、聚焦线圈设计和束流横向聚焦计算等.该加速装置经过测试各项指标已达到设计要求.     

一种用于C-ADS 低能束流传输线束流强度控制的新型可调限束光阑

为了实现超导直线加速器束流强度的连续可调,并满足加速器在线稳定可靠运行,针对我国加速器驱动次临界系统(C-ADS)低能束流传输线(LEBT)的束流强度调控,提出了一种新型的可调限束光阑。可调限束光阑采用两个相对旋转的镜像对称转芯,转芯的孔径在某一范围内可以实现连续变化,以刮除不需要的外部粒子,提高束流品质,降低束损,最重要的是可实现束流强度的在线连续可调,并满足圆形束的要求。仿真和试验结果表明,在0～10 mA范围内,可以有效地卡掉不需要的外部粒子束流,并实现束流强度的在线连续调节。该装置为质子直线加速器提供了一种方便的束流调试方法,能够满足ADS直线加速器稳定可靠的在线运行。     

中国散裂中子源快循环同步加速器壁电流探测系统

在中国散裂中子源工程中, 快循环同步加速器负责将剥离注入的能量为80MeV的质子束加速至1.6GeV后引出。在快循环同步加速器上共安装了两台壁电流探测器, 用来观测束流从注入至引出过程中束团在时域上的变化情况。详细介绍了壁电流探测器在陶瓷间隙、磁性材料和匹配电阻等方面的设计考虑, 以达到带宽满足百kHz到30 MHz的设计目标, 并对实际带束流测量结果进行分析讨论。经实际在线运行测试, 此壁电流探测器完全满足束流调试及运行需要。     

1.5MeV直线感应加速器的初步调试

本文介绍了新近在中国工程物理研究院建成的一台直线感应加速器。这台加速器由六个250kV的加速组元构成。其中四个用于构成电子源,另外两个用作后加速。输出电子束能量为1.5MeV,束流2—3kA,束脉冲宽度90ns,束的非归—化均方根发射度70mrad-cm。     

加速器科学与技术

1998年直线加速器向储存环提供了4080小时的束流，包括注入能量为1．55GeV的束流。总运行效率达98.1％。表4．1．1是该年度的总体运行统计，表4．1．2为该年度的工作安排。     

TRIUMF ARIEL 电子直线加速器设计

TRIUMF 的三期升级工程(ARIEL) 计划建造一个 50 MeV 平均流强为10 mA的电子直线加速器作为注入器,通过光裂反应生成放射性核素。电子直线加速器包括两个主要部分：注入器和后加速器,注入器完成电子能量从100 keV到10 MeV的转换,随后的后加速器将电子能量从10 MeV加速到50 MeV。电子源拟采用重复频率为650 MHz的热电子枪提供初始能量为100 keV,束长为 171 ps的电子束。束流动力学模拟了几种不同的设计方案以获得最优化的设计,模拟显示通过对腔体以及聚焦元件的仔细设计以及电子枪出射电子的参数选择, 电子束能量在达到50 MeV时束长可以被聚焦到 11.75 ps (对应于1.3 GHz 频率下5.5°) ,并且可以使电子束在超导低温柜中的尺寸保持在1.26 cm以下。     

Effect of the transverse parasitic mode on beam performance for the ADS driver linac in China

The ADS(Accelerator Driven subcritical System) driver linac in China is designed to run in CW(Continuous Wave) mode with 10 m A designed beam current. In this scenario, the beam-induced parasitic modes in the ADS driver linac may make the beam unstable or deteriorate the beam performance. To evaluate the parasitic mode effect on the beam dynamics systematically, simulation studies using the ROOT-based numerical code SMD have been conducted. The longitudinal beam instability induced by the HOMs(High Order Modes) and SOMs(Same Order Modes) has little effect on the longitudinal beam performance for the current ADS driver linac design based on the 10 Me V/325 MHz injector I from previous studies. Here the transverse parasitic mode(i.e., dipole HOM)effect on the transverse beam performance at the ADS driver linac exit is investigated. To more reasonably quantify the dipole mode effect, the multi-bunch effective emittance is introduced in this paper.     

TRIUMF ARIEL 电子直线加速器设计

 TRIUMF 的三期升级工程(ARIEL) 计划建造一个 50 MeV 平均流强为10 mA的电子直线加速器作为注入器,通过光裂反应生成放射性核素。电子直线加速器包括两个主要部分：注入器和后加速器,注入器完成电子能量从100 keV到10 MeV的转换,随后的后加速器将电子能量从10 MeV加速到50 MeV。电子源拟采用重复频率为650 MHz的热电子枪提供初始能量为100 keV,束长为 171 ps的电子束。束流动力学模拟了几种不同的设计方案以获得最优化的设计,模拟显示通过对腔体以及聚焦元件的仔细设计以及电子枪出射电子的参数选择, 电子束能量在达到50 MeV时束长可以被聚焦到 11.75 ps (对应于1.3 GHz 频率下5.5°) ,并且可以使电子束在超导低温柜中的尺寸保持在1.26 cm以下。     

A CW superconducting linac as the proton driver for a medium baseline neutrino beam in China

In a long-term planning for neutrino experiments in China, a medium baseline neutrino beam is proposed which uses a continue wave (CW) superconducting linac of 15 MW in beam power as the proton driver. The linac will be based on the technologies which are under development by the China-ADS project, namely it is also composed of a 3.2 MeV normal conducting RFQ and five different types of superconducting cavities. However, the design philosophy is quite different from the China-ADS linac because of the much weaker requirement on reliability here. The nominal design energy and current are 1.5 GeV and 10 mA, respectively. The general considerations and preliminary results on the physics design will be presented here. In addition, the alternative designs such as 2.0 GeV and 2.5 GeV, which may be required by the general design, can be easily extended from the nominal one.     

Physical design of a 10 MeV LINAC for polymer radiation processing

In China, polymer radiation processing has become one of the most important processing industries. The radiation processing source may be an electron beam accelerator or a radioactive source. Physical design of an electron beam facility applied for radiation crosslinking is introduced in this paper because of it’s much higher dose rate and efficiency. Main part of this facility is a 10 MeV travelling wave electron linac with constant impedance accelerating structure. A start to end simulation concerning the linac is reported in this paper. The codes Opera-3d, Poisson-superfish and Parmela are used to describe electromagnetic elements of the accelerator and track particle distribution from the cathode to the end of the linac. After beam dynamic optimization, wave phase velocities in the structure have been chosen to be 0.56, 0.9 and 0.999 respectively. Physical parameters about the main elements such as DC electron gun, iris-loaded periodic structure, solenoids, etc, are presented. Simulation results proves that it can satisfy the industrial requirement. The linac is under construction. Some components have been finished. Measurements proved that they are in a good agreement with the design values.     

Beam experiments with a non-intercepting beam induced f luorescence profile monitor for the ADS LINAC

An accelerator-driven subcritical system(ADS) project was launched in China in 2011, aiming to design and build an ADS demonstration facility with the capability of more than 1000 MW thermal power. The driver linac is defined to be a 10 m A current of high energy protons at 1.5 Ge V in continuous wave operation mode. To meet the extremely high power and intense beam accelerator requirements, non-interceptive monitors for the beam transverse profile are required for this proton linac. Taking advantage of the residual gas as active material, the Beam Induced Fluorescence(BIF) monitor exploits gas-excited fluorescence in the visible spectrum region for transverse profile measurements. The advantages of this non-intercepting method are that nothing is installed in the vacuum pipe,component design is compact and there is no need for expensive signal processing electronics. Beam experiments have been performed under constant beam conditions. The helium spectrum has been verified with different optical filters, showing that a proper optical band-pass filter covering 400–500 nm is necessary for fluorescence experiments with helium. By changing gas pressure, it is shown that gas pressure is proportional to the signal amplitude but has no influence on detected profile width. Finally, a comparison experiment between the BIF monitor and a wire scanner shows that the detected profile width results of both methods agree well.     

Physics design for the C-ADS main linac based on two dif f erent injector design schemes

The China ADS（C-ADS） project proposes to build a 1000 MW Accelerator Driven sub-critical System around 2032. The accelerator will work in CW mode with 10 mA in beam current and 1.5 GeV in final beam energy. The linac is composed of two major sections： the injector section and the main linac section. There are two diferent schemes for the injector section. The Injector-scheme is based on a 325 MHz RFQ and superconducting spoke cavities of the same RF frequency and the Injector-scheme is based on a 162.5 MHz RFQ and superconducting HWR cavities of the same frequency. The main linac design will be diferent for diferent injector choices. The two diferent designs for the main linac have been studied according to the beam characteristics from the diferent injector schemes.     

Mismatch study of C-ADS main linac

The ADS accelerator in China is a Continuous-Wave(CW) proton linac with 1.5 Ge V beam energy,10 m A beam current, and 15 MW beam power. To meet the extremely low beam loss rate and high reliability requirements, it is very important to study the beam halo caused by beam mismatch, which is one major sources of beam loss. To avoid envelope instability, the phase advances per period are all smaller than 90 degrees in the main linac design. In this paper, simulation results of the emittance growth and the envelope oscillations caused by mismatch in the main linac section are presented. To meet the emittance growth requirement, the transverse and longitudinal mismatch factors should be smaller than 0.4 and 0.3, respectively.     

Design study of a radio-frequency quadrupole for high-intensity beams

The Rare isotope Accelerator Of Newness(RAON) heavy-ion accelerator has been designed for the Rare Isotope Science Project(RISP) in Korea. The RAON will produce heavy-ion beams from 660-MeV-proton to200-MeV/u-uranium with continuous wave(CW) power of 400 k W to support research in various scientific fields.Its system consists of an ECR ion source, LEBTs with 10 ke V/u, CW RFQ accelerator with 81.25 MHz and 500 ke V/u, a MEBT system, and a SC linac. In detail, the driver linac system consists of a Quarter Wave Resonator(QWR) section with 81.25 MHz and a Half Wave Resonator(HWR) section with 162.5 MHz, Linac-1, and a Spoke Cavity section with 325 MHz, Linac-2. These linacs have been designed to optimize the beam parameters to meet the required design goals. At the same time, a light-heavy ion accelerator with high-intensity beam, such as proton,deuteron, and helium beams, is required for experiments. In this paper, we present the design study of the high intensity RFQ for a deuteron beam with energies from 30 ke V/u to 1.5 MeV/u and currents in the m A range. This system is composed of an Penning Ionization Gauge ion source, short LEBT with a RF deflector, and shared SC Linac. In order to increase acceleration efficiency in a short length with low cost, the 2nd harmonic of 162.5 MHz is applied as the operation frequency in the D~+RFQ design. The D~+RFQ is designed with 4.97 m, 1.52 bravery factor. Since it operates with 2nd harmonic frequency, the beam should be 50% of the duty factor while the cavity should be operated in CW mode, to protect the downstream linac system. We focus on avoiding emittance growth by the space-charge effect and optimizing the RFQ to achieve a high transmission and low emittance growth. Both the RFQ beam dynamics study and RFQ cavity design study for two and three dimensions will be discussed.