剥离膜安装与空气动力学分析

在散裂中子源注入系统工作过程中,剥离膜是实现负氢离子转换为质子注入加速的关键部件。百nm到μm级厚度的剥离膜超薄易碎,安装及系统真空获得难度较高,一直是散裂中子源研究的重点。对比了国外膜片固定方式现状,通过设计剥离膜辅助安装装置,实现剥离膜样品批量安装;通过Fluent仿真分析,模拟得出膜片在不同进出口压差下真空获得过程中的压力分布、膜片附件空气扰动及系统空气流动,制定在不破坏剥离膜的前提下真空获得方案,并获得剥离膜系统超高真空环境。     

高剥离态Fe Ⅹ Ⅵ离子能级寿命测量

在原子能院串列加速器上,利用束箔方法,测量了能量为30 MeV Fe离子产生的高剥离态谱线跃迁结构的寿命值.在30 MeV时,Fe通过箔膜的电荷态分布在7+到17+,我们选择Fe XⅥ2p~6(~1S)4p—2p~6(~1S)5d(~2P_(3/2)~o—~2D_(3/2))的谱线,谱线波长124.696(?),能级寿命为79±4 ps.最后对实验误差进行了分析.     

中国散裂中子源RCS注入区H0CT测量系统研制

中国散裂中子源的强流质子加速器采用剥离注入的方式,碳膜将H^-剥离两个电子后变成质子,多圈涂抹注入到快循环同步环加速中,并加速至1.6 GeV。为了精确测量剥离膜的剥离效率并研究不同厚度剥离膜的使用寿命,在I-Dump束线上新研发并安装了一套束流流强探测器(H⁰CT),用于测量未完全剥离的H^-和H⁰(H^-被剥离一个电子)粒子。为了测量μA级束流,H⁰CT弱流强测量系统的研制考虑了外部干扰,配合探头、线缆及电子学低噪声的抗干扰设计,将环境噪声及干扰的影响降至最低,提高信噪比,实现了μA级脉冲电流的测量。     

750 keV射频四极注入器束流动力学设计

 描述了一台750 keV，201.25 MHz的射频四极注入器束流动力学设计。在考虑与35 MeV质子直线加速器匹配、功耗小、传输效率高等原则的基础上，提出了加速器的技术要求。给出了两套设计方案的主要参数和设计结果。分析了能散度、发射度、Twiss参数、注入流强和能量等参数在非理想匹配条件下对束流传输效率的影响。比较了两套方案的异同点。模拟计算结果表明，两套设计方案均可以满足物理要求，传输效率都在99.3%以上。     

高剥离态Fe XVI离子能级寿命测量

在原子能院串列加速器上,利用束箔方法,测量了能量为30MeVFe离子产生的高剥离态谱线跃迁结构的寿命值。在30MeV时,Fe通过箔膜的电荷态分布在7+到17+,我们选择Fe XVI 2p6 (1S) 4p -2p6 (1S) 5d（2P°3/2 -2D3/2）的谱线,谱线波长124.696 Å,能级寿命为79±4ps。并对实验误差进行了分析。     

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。     

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。     

中国散裂中子源快循环同步加速器主剥离膜设计

设计了中国散裂中子源(CSNS)快循环同步加速器(RCS)注入区的主剥离膜装置。为降低研制难度和成本，提高运行可靠性，选择了回转体式的结构。根据在线可调性、高稳定性、高定位精度和超高真空等技术难点，给出了CSNS/RCS主剥离膜的具体结构方案和控制方案。利用ANSYS有限元分析软件和材料力学原理，对设备的核心部件不锈钢同步带进行了模拟计算和理论分析。     

100 MeV电子直线加速器的物理设计

 能量为100 MeV左右的高性能电子直线加速器是第三代同步辐射光源注入器和自由电子激光注入器的重要组成部分,采用热阴极栅控电子枪、聚束系统和4根SLAC型加速管作为加速器主体结构,一套45 MW的速调管调制器系统和波导系统作为微波功率源系统。设计中,使用了国际通用的模拟软件对加速器的动力学特性进行了数值模拟和参数优化,电子束能量达到100 MeV以上,能散小于1%,归一化发射度小于30 mm·mrad。     

“神龙一号”直线感应电子加速器

"神龙一号"加速器是一台20 MeV直线感应电子加速器. 本文介绍了"神龙一号"的物理设计、研制过程和调试结果. 物理设计主要分析了加速器研制的技术难点,并给出各分系统应达到的技术要求和具体结果. 文中重点介绍了脉冲功率系统、注入器、束流的调试情况,调试结果表明,"神龙一号"加速器输出电子束的参数为：电子能量20MeV、束流强度2.5kA、束流脉冲宽度～70ns、能散度0.64%、发射度2060mm·mrad、打靶焦斑尺寸1.2mm .     

Study of energy deposition and stripper temperature for CYCIAE-100

Nowadays high intensity proton accelerators are extensively applied, and this paper gives particular emphasis on CYCIAE-100, a 100 MeV high intensity compact cyclotron being constructed at CIAE. For accelerators of this type, the study is focused on how to improve the beam intensity. As for CYCIAE-100, the charge-exchange extraction is used to get protons. So it is crucial to enhance the lifetime of the stripping foil, which is largely determined by the energy deposition on it. For this cyclotron, due to the influence of the magnetic field, the electrons will spin near the foil and lose energy each time when they cross the foil. The energy deposition refers to all the energy deposition of protons and electrons. This paper stresses the stripper study of CYCIAE-100, in which the particle distribution on the foil is simulated and the energy deposition of the protons and electrons stripped from the H- ions are calculated. The temperature distributions are then calculated as a main reference for the foil design.     

CSRm内靶实验中的轻离子束流寿命模拟研究

 建立了内靶对兰州冷却储存环主环束流影响的单粒子跟踪模拟程序,对pellet小丸靶和碳靶对束流带来的负面影响进行了模拟研究,主要讨论CSRm内靶实验中的束流存活率和束流寿命状态。结果显示利用厚度为1×10¹⁶ atoms×cm^-2小丸内靶时,2.6 GeV质子束流寿命在100 s量级,而对于目前技术水平下的碳膜靶 (厚度为 5×10¹⁷ atoms×cm^-2),质子束流寿命为s量级;束流寿命和束流能量基本成正比关系,束流寿命和内靶厚度近似成反比关系。     

Study of energy deposition and stripper temperature for CYCIAE-100

Nowadays high intensity proton accelerators are extensively applied, and this paper gives particular emphasis on CYCIAE-100, a 100~MeV high intensity compact cyclotron being constructed at CIAE. For accelerators of this type, the study is focused on how to improve the beam intensity. As for CYCIAE-100, the charge-exchange extraction is used to get protons. So it is crucial to enhance the lifetime of the stripping foil, which is largely determined by the energy deposition on it. For this cyclotron, due to the influence of the magnetic field, the electrons will spin near the foil and lose energy each time when they cross the foil. The energy deposition refers to all the energy deposition of protons and electrons. This paper stresses the stripper study of CYCIAE-100, in which the particle distribution on the foil is simulated and the energy deposition of the protons and electrons stripped from the H^－ ions are calculated. The temperature distributions are then calculated as a main reference for the foil design.     

Stripping extraction calculation and simulation for CYCIAE-100

A 100 MeV H- compact cyclotron is under construction at China Institute of Atomic Energy (CYCIAE-100). The proton beams of 75 MeV-100 MeV at an intensity of 200 μA will be extracted in dual opposite directions by charge exchange stripping devices. The crossing point at the switching magnet center is fixed inside the magnet yoke and the stripping points for various extraction energies are calculated by the code CYCTRS. With the code GOBLIN, we can calculate the transfer matrix including the dispersion effects from the stripping point to the switch magnet. The beam distribution just after stripping foil can be obtained from the multi-particle tracking code COMA and the extracted beam parameters after the switch magnet such as emittance, envelope, dispersion, energy spread, bunch length, etc. are given by the extraction orbit simulations.     

HITFiL同步加速器剥离注入

一台新的治癌专用加速器HITFiL正在设计和建造中,其中一台同步加速器为其主加速器,以高紧凑性、高可靠性和低成本为设计目标。同步加速器的注入系统采用剥离注入方式,剥离注入与单圈注入方式相比能达到较高的注入效率,而其造价明显低于多圈注入加电子冷却的注入方式。治癌采用碳粒子束,从ECR离子源产生的C5+离子经过回旋加速器预加速后在同步加速器注入点处剥离成为C6+注入到环里。详细阐述了该注入系统的设计方案,并对整个注入过程进行了计算机模拟。在模拟过程中,对束流的注入效率、束流损失机制和粒子数增益进行了研究,得到了实空间和相空间的粒子分布和发射度增长趋势,得到了满足要求的束流流强。     

Application of aluminum and titanium foils in low-energy wide-aperture electron accelerators

We have reported on the results of theoretical and experimental investigations of characteristics of aluminum and titanium foils used in devices to extract electron beams from wide-aperture low-energy accelerators with a high current density. The mechanical properties of foils at different temperatures and the electron beam transmission and absorption coefficients have been compared. The results of analyzing the dependences of the efficiency of the electron beam extraction from accelerators on the type of the electron–optical system, material, and thickness of the foil for various sizes of extraction windows and the same type of the slot support grids have been presented. We have proposed an analytic model for calculating the temperature of the foil in the unit cell of the support grid. The electron transmittance and absorbance, as well as the temperature regimes of the foils, have been calculated using different methods.     

Dissociation of CN+ into atomic excited states after acceleration in a tandem accelerator

A CN⁺ beam produced by stripping CN^- in the terminal of a Pelletron Tandem accelerator was dissociated in a thin carbon foil. Optical observations of ultraviolet transitions of C III–C IV and IV - N V showed intensity variations as a function of foil thickness. The results indicate an enhancement of population due to the neighboring partner projectile for some but not all excited states.     

Experiments and analysis of thin tungsten slice and W/Cu brazing for primary collimator scraper in CSNS/RCS

According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.     

低能宽幅电子束引出特性研究

研究了能量在100到300 keV区间的低能宽幅电子束从真空引出到空气中的特性。利用EGS5程序模拟了电子束穿过不同厚度钛箔后,在空气中距离钛箔5~10 cm距离处的能量损失、束流损失和束流分布均匀性等。模拟结果显示,对于低能电子,钛箔厚度应该在10 μm左右为宜,其透射率与能量直接相关,在距离钛箔5 cm的位置,电子束的分布不均匀度低于±2%,优于工业应用±10%的标准（特殊情况下要求为5%）,完全满足工业辐照要求。In order to investigate the characteristics of extracting low-energy electron beam from vacuum into air, EGS5 is used to simulate the energy loss, beam loss and spatial distribution uniformity at the irradiation position, which is 5~10 cm to titanium foil with different thickness. The simulation results show that the transmittance is directly related to the incent energy of low-energy electron. When the titanium foil thickness is 10 μm, the inhomogeneity about the energy beam spatial distribution is below 5% on the treatment plane 5 cm away from the titanium foil. And totally meet the industrial needs.