强流直线感应加速器中束流质心横向运动初步计算

 “神龙一号”强流脉冲加速器由72个直线感应加速腔和18个用于测试和真空泵接口的多功能腔组成。直线感应加速器的研制建造中磁轴对中偏差和聚焦磁场的自然偏差所引起的束流质心偏移轨道中心是不可避免的，由于束脉冲期间存在能散，使束流产生Corkscrew运动,导致束流品质变坏。而束脉冲期间的能散只能减小到一定水平，因此必需采取一定的措施抑制Corkscrew幅度的增长。在加速器的安装阶段，脉冲悬丝技术被应用于准直加速段聚焦磁场，并在磁轴准直测试的同时对磁场固有倾斜偏差进行初步校正。根据脉冲悬丝测试所得实验数据，采用传输矩阵法对加速段束质心轨迹进行了初步估计，计算中考虑了各加速腔聚焦磁场的倾斜和偏移误差。给出了计算结果和分析。     

法兰-螺栓连接对加速器对中装配同轴度的影响

由于直线感应加速器束输运系统磁场准直偏差和束脉冲期间所引起的束流Corkscrew运动是导致发射度增长的重要原因之一，因而提高磁场准直精度是抑制和减小Corkscrew振幅的重要措施。机械轴的精密对中是磁轴准直及磁场误差校正的基础。     

“神龙一号”直线感应加速器多功能腔设计

 多功能腔集真空泵安装、束流过渡漂移、束流在线测量及方便机器检修等诸多功能于一体，是“神龙一号”加速器束流传输系统的一个关键部件。简要介绍了多功能腔设计中的磁轴准直、输运磁场的连续性以及横向阻抗几个关键问题，阐明了多功能腔的可维修特性和磁轴准直性能，分析了多功能腔对输运磁场连续性的影响，计算了多功能腔的低横向耦合阻抗，并提出了降低横向耦合阻抗的措施。多功能腔的应用简化了束流传输线的结构，提高了束流传输线的性能，将在“神龙一号”直线感应加速器的调试中起到非常重要的作用。     

采用脉冲悬丝法测量强流加速腔聚焦场磁轴

 介绍了利用脉冲悬丝法校正、测量加速腔磁轴，以及对10MeV LIA束输运系统中40cm长聚焦线圈磁轴偏差的测量，详细描述了实验装置和实验方法。从测得的电压波形可区分出磁轴的倾斜与偏移，并可辨别出倾斜与偏移的方向，在聚焦线圈轴向磁场最强为0.072T的条件下，通过多次实验改变悬丝电流从0 .3A到3.8A，并改变电流脉冲宽度从0.3ms到1.5ms，测出了40cm聚焦线圈磁轴的偏差，并给出了磁轴偏差分布的对应波形。测试灵敏度估计为磁轴倾斜1mrad, 偏移0.2mm。     

“神龙一号”直线感应加速器物理设计

 介绍了 “神龙一号”直线感应加速器物理设计的主要考虑。“神龙一号”加速器是一台电子直线感应加速器，由3.6MeV感应迭加型注入器、72个感应加速腔、脉冲功率系统、束流输运和聚焦系统、控制系统和真空、绝缘油、绝缘气体以及去离子水系统组成。能产生20MeV、束流大于2.5kA，脉冲宽度为60ns的强流脉冲电子束，X光焦斑均方根直径为1.5mm。     

辐照用紧凑连续波电子加速器的物理设计

为适应工业电子加速器需求增多的现状,提出了一种新型的结构紧凑的连续波电子加速器,运行频率为180MHz。依靠置于加速腔外的多个偏转磁铁,使电子束多次穿越加速腔,从而得到持续的加速。设计过程中,用CST软件对谐振加速腔进行了优化,用Parmela软件模拟了束流的粒子动力学。粒子纵向稳定度和横向聚焦也通过模拟进行了分析和验证。结果显示:此种新型加速器能得到9MeV,100kW的稳定电子束流。     

HIAF电子冷却装置高精度线圈磁轴测量

强流重离子加速器装置（HIAF）将采用电子冷却技术,降低重离子束流的发射度和动量分散,提高核物理及原子物理实验的精度与亮度。电子冷却装置的冷却段磁场均匀度是影响冷却效率的主要参数,HIAF电子冷却装置采用多个独立高精度线圈串联产生纵向磁场的设计,获得极高的冷却段磁场均匀度。本文介绍了一种测量高精度线圈磁轴偏角的装置,采用定位装置测量线圈的几何对称轴,通过旋转霍尔探头测量线圈中心平面上的径向与轴向磁场分布,再根据磁场测量数据计算出线圈磁轴与几何对称轴之间的偏角。实际测量表明该装置的磁轴偏角测量精度达到±0.10 mrad。测量得到的HIAF电子冷却装置冷却段线圈样品的磁轴偏角为（1.28±0.10）mrad,达到设计要求。     

Corkscrew运动影响束流发射度的数值分析

在直线加速器中，始终存在束流质心轴、束流传输管道几何轴、束流聚焦传输磁场磁轴等三轴不一致问题。当束轴与磁轴存在夹角，而且束流脉冲（平顶）期间存在能量差别时，将引起束心的Corkscrew运动。斜入射的束流在轴向磁场中传输时，由于束流脉冲（平顶）期间不可避免的能量差别，导致不同时刻的束片质心螺旋运动的相位不同，在束流到达同一个位置时，不同时刻束片的质心在同一个考察点具有不同的横向位置。束心Corkscrew运动会造成很多不良后果。针对束心Corkscrew运动造成束流积分发射度的增长情况开展数值模拟研究，为采取相应的抑制措施提供参考和依据。     

直线感应加速腔横向阻抗的测量

 采用束流模拟法测量强流直线感应加速器加速腔横向阻抗,给出了加速腔的测量结果。采用了时域变换法提高不匹配情况下测量精度的方法,对引起测量误差的 原因进行了分析。这有助于深入理解强流加速腔内的物理过程,改进加速腔设计,提高 直线感应加速器整机性能     

用于远红外FEL的直线加速器物理模拟计算

波长在２００μｍ附近的自由电子激光对电子束品质有特别要求，不仅要求较长的束流微脉冲，而且对流强、能散度以及束流参数对加速器噪声的稳定性等都有很高的要求。我们采用ＰＡＲＭＥＬＡ程序，对一台由１０８ＭＨｚ分频预聚束器、９腔１３００ＭＨｚ聚束加速段和９腔１３００ＭＨｚ加速段组成的加速器进行了大量模拟计算，得到了满足ＦＥＬ要求的物理设计方案和对加速器各部件稳定性的要求指标。     

Alignment techniques for DRAGON-Ⅰ LIA

DRAGON-Ⅰ designed and manufactured by CAEP is a linear induction accelerator which can produce a 20 MeV-3 kA-60 us electron beam. The high performance required for the machine is determined by the beam quality and thus is greatly dependent on the accelerator alignment. In order to reduce the chromatic effect of the beam, the stretched wire technique has been developed to measure magnetic axes of the cells precisely, and the dipole steering magnets have been equipped into each cell to correct its magnetic axis misalignment. Finally, the laser tracker has been used to examine the installation error of the accelerator. In this paper, different alignment techniques and the primary results are presented and discussed.     

Analysis and experimental concepts of the vibrating wire alignment technique

The vibrating wire alignment technique is a method which, by measuring the spatial distribution of a magnetic field, can achieve very high alignment accuracy. The vibrating wire alignment technique can be applied to fiducializing magnets and the alignment of accelerator straight section components, and it is a necessary supplement to conventional alignment methods. This article gives a systematic summary of the vibrating wire alignment technique, including vibrating wire model analysis, system frequency calculation, wire sag calculation, and the relation between wire amplitude and magnetic induction intensity. On the basis of this analysis, this article outlines two existing alignment methods, one based on magnetic field measurement and the other on amplitude and phase measurements. Finally, some basic experimental issues are discussed.     

相对论磁控管中自磁场的影响

针对相对论磁控管中自磁场的产生与分布、自磁场对电子运动的影响以及自磁场对互作用的影响进行了深入分析。分析认为,由于自磁场分布的不对称,自磁场对不同区域电子束的作用不同。加速器一侧的电子束受到更明显的自磁场作用,促使此区域的电子束角向速度增加,直接激化模式竞争。同时,如果阴极比较靠近加速器一侧的1/4区域(距磁控管对称中心大约1/4高度),模式竞争将进一步被激化。     

对HIRFL几个主要参数的稳定性要求

对ＨＩＲＦＬ（兰州重离子研究装置）的几个主要参数的稳定性对束流指标及运行效率的影响进行了分析,如高频的幅度稳定和相位稳定及主磁场的稳定等,并提出了合理的稳定度要求和需要采取的措施． The stability of the main parameters at HIRFL accelerator complex, which is important to get high extraction efficiency of the beams from cyclotrons has been studied. The RF amplitude stability and the stability of main magnetic field are the key parameters. The reasonable requirements for the parameters at HIRFL and the measures to reach them are proposed.      

第四代ECR离子源的主要概念(摘要)

To go beyond the present and planned third generation ECR ion sources operating at microwave frequencies between 20 and 30GHz to a fourth generation of sources operating above 50GHz offers new oppor- tunities and challenges.Based on the experimentally demonstrated frequency scaling,a doubling in operating frequency could provide more intense high charge state beams with higher charge states.The technical chal- lenges include the development of magnetic structures capable of producing 8T solenoid field and 4T sextupole fields,production and coupling of high power microwave power to heat the plasma,extraction of intense mul- tiple charge ion beams from a region of strong magnetic field and shielding of bremstrahlung from the hot electrons.In this paper,the status of high field superconducting magnets now under development for acceler- ator applications,gyrotrons for microwave power and other technical aspects that would be incorporated into a fourth generation ECR ion source are explored and applied to a conceptual design.     

Radioactive nuclear beams: Present and future

Some results of investigations into a new nuclear-physics field associated with the production of radioactive nuclear beams and physical studies with these beams are presented. The most recent results obtained by studying the structure of nuclei and reaction mechanisms with radioactive nuclear beams are surveyed. Data obtained in Dubna at the DRIBs accelerator complex are presented along with allied results from other research centers. In this connection, existing experimental data on light loosely bound exotic nuclei are discussed. The parameters of DRIBs3, which is a new accelerator complex, are presented, and the physics research program that will be implemented with the aid of new setups, including a high-resolution magnetic analyzer (MAVR) and a 4π neutron detector (TETRA), is described. A collaboration in the realms of employing radioactive nuclear beams at the DRIBs complex together with other accelerator complexes [SPIRAL2 (France), RIKEN (Japan), FAIR (Germany), and RIBF (CIIIA)] on the basis of employing new highly efficient experimental facilities has already led to the discovery of new phenomena in nuclear physics and will make it possible to study in the future new regions of nuclear matter in extreme states.     

直线感应加速器机械轴精密对中方法

 介绍了大型直线感应加速器机械轴精密对中安装方法和工艺。直线感应加速器由多个组元连接而成，总长几十m。采用激光跟踪仪并配以全站仪、水准仪进行准直测量，再用专门设计的高精度调节机构调节，可使机械轴的准直达到较高的精度。分析了准直安装各步骤能达到的精度，研究了几十m长机械轴准直控制测量网的建立和理论坐标值的修正。     

Pulse compression in radio frequency photoinjectors-applications toadvanced accelerators

While RF photoinjectors are an excellent source of high brightness electron beams, there are constraints to tying together the expected emittance and peak current performance of a given photoinjector system. These constraints, which arise from the complicated dynamics of the electrons due to the interplay of RF and space-charge forces within the photoinjector, tend to favor lower peak current operation. For some ultimate uses of photoinjector beams, such as linear collider test beams, wakefield accelerators, and free-electron lasers (FEL's), one may desire much higher peak currents. In this case, an inexpensive and reliable method for producing extremely short high-current electron bunches is to use magnetic compression. We examine this scheme analytically and by computer simulation. Many applications are illustrated, including the TESLA Test Facility/FEL injector, ultra-high current beams for plasma wakefields and generation of femtosecond electron pulses for injection into short wavelength laser-based accelerators. It is shown that the injection timing jitter associated with the laser can be nearly eliminated using this scheme, making it an indispensable component in many of the advanced accelerator injectors we consider     

三阴极强流加速器研制

 研制了一台能同时产生3电子束的高功率强流加速器,该加速器主要由初级储能部分、线绕式脉冲变压器、水介质形成线和三阴极二极管组成,3根阴极分别伸入3个独立的漂移管,对3个电子束之间相互作用的电磁力起屏蔽作用。当该加速器二极管接单个阴极时,产生的电功率超过50 GW;当该加速器二极管同时接3个阴极时,产生3个电子束的电功率分别超过10 GW;当该加速器被用于驱动3个高功率微波管时,能产生L波段1.0 GW,S波段1.0 GW和C波段300 MW的微波输出。