The effects of beam line pressure on the beam quality of an electron cyclotron resonance ion source

The results of a series of measurements studying the possibility to use neutral gas feeding into the beam line as a way to improve the quality of the heavy ion beams produced with an electron cyclotron resonance ion source (ECRIS) are presented. Significant reduction of the beam spot size and emittance can be achieved with this method. The observed effects are presumably due to increased space charge compensation degree of the ion beam in the beam line section between the ion source and the analyzing magnet. This is the region where the neutral gas was injected. It is shown that the effects are independent of the ion source tuning. Transmission measurements through the beam line and K-130 cyclotron have been carried out to study the effects of improved ion beam quality to the transmission efficiency.     

Design of a low energy positron beam

A low energy positron beam apparatus has been designed and constructed. Experimental details are presented and the performance characteristics are described.     

高梯度加速管的束流传输

对不同能量、不同质量数、不同初始条件的入射束和有无空间电荷效应的离子束流在高梯度加速管中的传输进行了计算，并讨论了一些影响加速管聚焦作用的主要因素，计算结果与实际情况相符。     

电子束注入PMMA空间电荷分布的Monte-Carlo模拟与实验验证

精确控制和测量电子束注入样品后电荷量以及电荷的沉积分布,对于进行高压电力电缆材料的击穿以及航空器受到高能宇宙射线破坏的研究有着非常重要的意义。本工作结合空间电荷对固体电介质材料击穿影响的研究课题,利用Monte-Carlo方法模拟计算了电子束注入聚甲基丙烯酸甲脂(PMMA)样品中电荷的沉积分布,并通过激光感应压力波法(LIPP)对电子束注入后的PMMA进行测量;实验验证计算结果,吻合较好,为以后实验参数的设计提供了重要依据。     

Characteristics of the beam injection system in an electron LINAC

The main characteristics of an electron beam injection system are described; the system is used for injecting and focusing electron beams into the acceleration structure of an 10 MeV linear electron accelerator. The beam injection system consists of a Pierce convergent diode-type electron gun with pulse modulator for power supply and a thin axially symmetric lens. The perveance and the capture coefficient were optimized by the analogical resistors network. This type of injection system was used in the linear electron accelerators: ALIN - 3 MeV, ALIN - 10 MeV and ALID − 8 MeV, performed at NILPRP^∗ Bucharest, Romania.     

低能重离子束注入小麦种子诱导根尖细胞有丝分裂畸变的研究

比较研究了低能重离子束注入小麦干种子和萌动的种子对种子发芽及根尖细胞有丝分裂畸变的影响。结果表明,离子注入对萌动的种子的发芽有明显的影响,而对干种子的发芽影响不明显。在一定剂量范围内(0-6×1016/cm2),N+注入诱导的萌动种子的有丝分裂畸变率略高于干种子,并且随辐射剂量的升高而升高;但超过一定的剂量(>6×1016/cm2),无论是干种子还是萌动种子的有丝分裂畸变率达到一定程度的饱和。就实验结果对N+离子束注入诱变的机理进行了一些探讨。     

Simulation of high-intense beam transport in electrostatic accelerating column

An electrostatic accelerating column was designed and fabricated by Lanzhou University for an intense DT/D-D neutron generator. In order to achieve a neutron yield of 5.0 × 10~(12)n/s, a deuteron beam of 30 mA,accelerated to 400 kV, and transported in the electrostatic accelerating column smoothly are required. One particle-in-cell code BEAMPATH was used to simulate the beam transport, and the IONB 1.0 code was used to simulate the intense beam envelopes. Emittance growths due to space charge effect and spherical aberration were analyzed. The simulation results show that the accelerating column can transport deuteron beam of 30 mA smoothly and the requirement for the neutron generator is satisfied.     

束流位置探头用于束团电荷量测量的数值仿真研究

加速器常用的束流位置探头为电磁耦合型,其输出信号包括束流位置信息和束团电荷量信息.本文采用数值仿真方法研究探头电极和信号与束流位置之间的关系,基于Matlab开发一个用于仿真计算探头电荷量标定系数的软件包.对上海光源储存环束流位置探头的仿真结果表明,探头流强标定系数在2.5 mm半径内差值小于千分之二,在此精度范围内可认为流强标定系数为常数.     

All-metal transformer core for a low aspect ratio tokamak

A novel concept for incorporating an iron core transformer within a axisymmetric toroidal plasma containment device with a high neutron flux is described. This design enables conceptual design of low aspect ratio devices which employ standard transformer-driven plasma startup by using all-metal high resistance inserts between the toroidal field windings. This design avoids the inherent problems of a multi-turn air core transformer which will inevitably suffer from strong neutron bombardment and hence lose the integrity of its insulation, both through long term material degradation and short term neutron induced conductivity. A full 3-dimensional model of the concept has been developed within the MAXWELL program and the resultant loop voltage calculated. The utility of the result is found to be dependent on the resistivity of the high resistance inserts. Useful loop voltage time histories have been obtained using expected resistivities.     

注砷硅片低能电子束退火

本文报道了用低能大面积电子束处理注砷硅片的实验结果。由四探针和背散射、沟道效应测量结果表明，用本方法退火的样品具有电激活率高和砷原子再分布小的优点。     

呈任意能量分布的核信号模拟

针对核信号在脉冲幅度和相邻脉冲产生的时间间隔上存在的随机性,探讨了核信号统计特性的模拟方法.在进行核信号的能量随机性模拟中,可将核信号的统计特性分解为均匀分布、高斯分布、指数分布、多项式分布和泊松分布等基本分布,并用本文所述方法来实现;对于不便于分解、呈任意能量分布的核信号也可用此法实现,模拟效果较好.     

Diagnosis and dynamics in a simple low energy medium current electron beam channel

We present a simple experimental setup and an associated method enabling both the non-destructive diagnosis and the calculation of the beam evolution in a low energy medium current electron beam channel, where the space-charge and emittance effects are comparable. The diagnosis makes use of an axially symmetric magnetic lens while a second lens is added to increase the flexibility in the beam processing. The paper emphasizes the three steps involved in the method: the evaluation of the lenses' magnetic field by numerical simulation, the beam diagnosis, and the computation of the beam envelope. The calculation of the magnetic field is based on the finite element method. Subsequently, the beam parameters at the electron source exit – emittance and cross-over radius and position – are found with the modified three gradient method. Finally, the beam dynamics are modeled with the K–V equation adapted for the particular case of axial symmetry. The results obtained in this paper can be used to optimize technological processes, such as welding, hardening, cladding, and surface alloying.     

Synthesis of carbon-nitride films using a fast-switched dual-source low energy ion beam deposition system

Thin C_xN_y films were deposited in UHV using alternating low energy ion beams of C⁺ and N⁺ or N₂⁺ in the energy range of 5 to 100 eV. The ion beam deposition system is equipped with two Freeman ion sources, mass analysis and fast automated beam switching, allowing perpendicular bombardment of the target with a single ion beam at a time. The composition and density of the films were studied by ARS (in situ), XPS and RBS. The dependence of the film properties and growth mechanisms on ion energy, beam switching rate, and C-to-N arrival ratio have been investigated. The influence of the deposition parameters on the film stoichiometry is discussed. Exposure of the film to atmosphere leads to oxygen incorporation, resulting in a lowered surface concentration of nitrogen. The XPS N 1s and C Is binding energies vary in a relatively broad range indicating that several bond states may be present. The influence of the substrate material on film growth has also been studied. On Si{100}, film growth commences with the formation of an interfacial silicon nitride. No film growth was observed on gold, however deposition was possible on tantalum and molybdenum.     

The new Cyclone 18/9 beam transport line at the CNA (Sevilla) for high energy PIXE applications

The Cyclone 18/9 cyclotron system at the Centro Nacional de Aceleradores (Sevilla, Spain) is commonly used to create short life radioisotopes for PET applications. Besides, an external beam transport line has been recently installed in one of the target ports with two major purposes: to study the effects of 18 MeV protons irradiation on the behaviour of electronic devices for space applications and to complement the analysis of materials using our 3 MV tandem accelerator with the PIXE measurements at high energy.In this work, the main elements of our beamline will be briefly described and the first PIXE application will be presented. The usual PIXE, in the analysis of archaeological metallic objects, using around 3 MeV protons requires having a shiny area. Our purpose is to obtain a deeper determination of the bulk composition bombarding with 18 MeV protons through the corroded samples surfaces, without polishing the ancient object. To check this methodology high energy PIXE has been performed on two fibulae of the Later Bronze Age and First Iron Age, coming from the area around Sevilla.     

Dynamic energy spectrum and energy deposition in solid target by intense pulsed ion beams

A method for analyzing the dynamic energy spectrum of intense pulsed ion beam (IPIB) was proposed.Its influence on beam energy deposition in metal target was studied with IPIB produced by two types of magnetically insulated diodes (MID).The emission of IPIB was described with space charge limitation model,and the dynamic energy spectrum was further analyzed with time-of-flight method.IPIBs generated by pulsed accelerators of BIPPAB-450 (active MID) and TEMP-4M (passive MID) were studied.The dynamic energy spectrum was used to deduce the power density distribution of IPIB in the target with Monte Carlo simulation and infrared imaging diagnostics.The effect on the distribution and evolution of thermal field induced by the characteristics of IPIB dynamic energy spectrum was discussed.     

单能光子在HPGe探测器上的能量响应函数模拟

根据单能光子与探测器发生相互作用的原理,本文利用蒙卡方法(MC)模拟了系列单能光子在HPGe探测器上的能量响应曲线并提取曲线的特征数据,然后采用最小二乘法对提取的特征数据进行拟合,得到单能光子在该探测器上的能量响应曲线理论函数表达式,最后采用准单能γ源测量数据对理论表达式进行修正,确立了该响应函数随光子入射能量变化的修正函数表达式,为连续光子能谱解谱提供了依据.     

计算脉冲电子束辐照下能量沉积剖面的新方案

脉冲电子束辐照材料试验研究中,束流电子具有不同的速度和角度分布。但数值模拟计算一般都考虑电子束垂直入射靶材料,这可能导致数值计算结果与试验结果不符。针对该问题,提出了一种计算电子束辐照下能量沉积剖面的新方案,利用MCNP(Monte Carlo N Particle Transport Code)软件对铝、铜、钽金属材料在电子束辐照下的能量沉积进行模拟,分析了电子束垂直入射与带有角度分布入射时能量沉积的差异,为解释电子束辐照试验测量数据与理论计算结果之间的差异提供了依据。     

低能电子束循环辐射硫化天然橡胶乳液

应用250keV低能电子束循环辐射硫化二丙烯酸壬酯（1,9-nonanedilo diacrylate，NDDA）敏化的天然橡胶乳液，探讨了影响低能电子束循环辐射硫化天然橡胶乳液的因素。结果表明，提高电子束束流，可缩短辐射硫化时间；40％的天然橡胶乳液更适合低能电子束的辐射硫化；适当提高循环乳液的重量有利于辐射硫化乳液的质量控制。     

半球形偏转电子能量分析器的设计和应用

本文较详细地介绍了静电半球偏转电子能量分析器的原理，设计和实际制作，并说明半球分析器作为单色器和分析器在中能电子能量损失谱仪的成功使用。     

Simulation of damage to tokamaks plasma facing components during intense abnormal power deposition

Intense power deposition on plasma facing components (PFC) is expected in tokamaks during loss of confinement events such as disruptions, vertical displacement events (VDE), runaway electrons (RE), or during normal operating conditions such as edge-localized modes (ELM). These highly energetic events are damaging enough to hinder long term operation and may not be easily mitigated without loss of structural or functional performance of the PFC. Surface erosion, melted/ablated-vaporized material splashing, and material transport into the bulk plasma are reliability-threatening for the machine and system performance.A novel particle-in-cell (PIC) technique has been developed and integrated into the existing HEIGHTS package in order to obtain a global view of the plasma evolution upon energy impingement. This newly developed PIC technique is benchmarked against plasma gun experimental data, the original HEIGHTS computer package, and laser experiments. Benchmarking results are shown in this paper for various relevant reactor and experimental devices. The evolution of the plasma vapor cloud is followed temporally and results are explained and commented as a function of the computational time needed and the accuracy of the calculation.