多路激光聚焦系统的均匀性分析

本文建立了一套光束焦斑均匀性测量系统，获得了单束与多束聚焦系统的焦斑图像。基于Matlab图像处理与图形用户界面（GUI）设计技术，开发了一套多束激光聚焦系统的均匀性计算程序，可快速有效地给出单束与多束聚焦模拟的不均匀因子与相应的能量占有率（又称桶中功率，PIB）。计算结果表明：当能量占有率为70%时，“天光一号”装置六束聚焦焦斑的不均匀因子小于2%，可为状态方程实验研究提供均匀的焦斑条件。     

脉冲慢束空间聚焦的SIMION模拟

用SIMION 7.0光学离子模拟软件对正电子在慢正电子束装置的静电及静磁场中的加速、输运、空间聚焦情况进行了模拟计算,初步得到了很好的空间聚焦模拟结果。对于加速能量为0.5～30keV的正电子束流聚焦半径控制在5 mm以下,满足了实验的需要。     

10MeV电子直线加速器磁聚焦系统研究进展

磁聚焦系统是电子直线加速器的重要组成部分,10 MeV电子直线加速器的磁场聚焦系统主要依据加速管轴线上的磁场分布进行工程设计。 1 设计要求 依据束流动力学理论计算的结果(图1)进行设计。 图1 理论磁场曲线图 2 聚焦元件布局 根据理论磁场曲线,在加速管上布置6个聚焦线圈     

光学速调管自由电子激光的理论研究

该项目由国家 863 计划和国家自然科学基金资助的理论研究和数值模拟课题。其目的是对光学速调管紫外波段自由电子激光进行理论研究和数值模拟,从而达到对光学速调管自由电子激光规律的认识和掌握实验方案的理论设计能力。研究的内容包括光学速调管内磁场的计算,电子束的能量调制,电子束的密度调制,光学速调管的自发辐射谱和增益谱的计算,谐波超辐射的计算,磁场误差对能量调制的影响和对自发辐射谱的影响等。所有这些工作对实验方案的设计是有实际应用价值的。     

海关集装箱检测用电子直线加速器聚焦线圈磁场设计与测试

介绍了在电子直线加速器粒子动力学基础上进行聚焦线圈轴向磁场的设计；利用ＬＩＮＥ－ＡＣＣ／ＰＣ程序模拟计算，给出了不同初始发射度情况下满足束流包络要求的各种聚焦磁场数据。对已经加工好的聚焦系统进行了磁场分布测量，并将实际磁场与理论计算进行了比较。上述工作为确定聚焦线圈的设计方案和加速器的出束实验提供了可靠、丰富的数据。     

高功率KrF准分子激光及束靶相互作用研究进展

6束角多路高功率KrF系统经运行考验,对MOPA系统光学元件、激光开关、同步高压脉冲触发系统等影响系统稳定的因素进行了改进。经专家小组检查,实测电子束能量不稳定性小于5％,激光能量稳定性可达到5％～10％（每炮能量重复）。 用此系统的一束激光（30J/23ns）配合上海光机所进行了受激喇曼散射（SRS）实验,脉冲宽度压缩实验效率约为17％,脉宽压缩15倍。此外,在前端进行了受激布里渊散射（SBS）压缩脉宽研究工作。 进行了束靶作用初步实验,包括X射线针孔照像、离子飞行时间测量以及探测器（光电     

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。     

海关集装箱检测用电子直线加速器聚集线圈磁场设计与测试

介绍了在电子直线加速器粒子动力学基础上进行聚集线圈轴向磁场的设计；利用ＬＩＮＥ－ＡＣＣ／ＰＣ程序模拟计算，给出了不同初始发射度情况下满足束流包络要求的各种聚焦磁场数据。对已经加工好的聚焦系统进行了磁场分布测量，并将实际磁场与理论计算进行了比较。上述工作为确定聚焦线圈的设计方案和加速器的出束实验提供了可靠、丰富的数据。     

15 TW激光与氮气作用产生稳定电子束的实验研究

利用15 TW激光脉冲,系统研究了基于电离化注入的激光尾波场加速。实验中,研究了等离子体密度、相互作用位置、激光脉宽以及激光能量对电子束的电荷量、发散角、指向性、能量以及产生概率的影响。将约400 mJ、25 fs的激光脉冲聚焦在喷嘴前沿,等离子体密度约9×10¹⁸ cm^-3时,电子的产生概率高达100%,获得了水平（竖直）发散角（6.5±0.5） mrad（（5.3±0.3） mrad）、水平（竖直）指向稳定性±1.2 mrad （±0.7 mrad）、峰值能量（135±8） MeV和电荷量（13.5±2.0） pC（＞50 MeV）的稳定电子束,为其应用奠定了基础。     

300kV,5电极负离子束系统的数值模拟研究(英文)

根据用于负离子-中性束注入器的强流负离子引出、加速系统的特点,建立了负离子束系统的数值模拟模型和程序,以便辅助该系统的设计。计算了负离子束和伴随引出的电子束在系统电、磁场共同作用下的运动行为,研究了束密度、负离子初始温度和剥离损失及末电极孔位移等相关参数对负离子束光学特性的影响,优化了电、磁场位形。对 300 kV,5 电极负离子束系统的初步优化结果表明:该系统磁场可以在低能下将电子束偏转到作为接收器的引出电极上;设 H-离子在引出区的剥离损失为 20%并且引出的 H-束密度为 21 mA·cm- 时,所有出射小束的均方根散角和 85%束散角分别 2为 0.327°和 0.460°。     

Thickness distribution of high-speed free-surface lithium flow simulating IFMIF target

International Fusion Materials Irradiation Facility (IFMIF) employs liquid lithium as D⁺ beams target. The liquid Li target is formed as flat plane free-surface flow by a nozzle and flows at high speed around 15 m/s. This paper focuses on flatness of the liquid Li target. The Li flow experiment was conducted in Osaka University Li Loop with a test section which was 1/2.5 scaled model of IFMIF. The thickness of the Li flow was measured and obtained by a contact method which was developed for the measurement. Analytical study on Kelvin wake and numerical calculation on the wake near the side wall of the flow channel were also conducted and compared with the experimental results. As a result, the positions of the wake crest obtained from both of the experiment and numerical calculation assuming contact angle 140° agreed well with the iso-phase line of the analytical model. The generation of the wake likely depends on wettability between Li and the structural material which is 304SS in the present study.     

An experimental apparatus proposed for efficient removal of isobaric contaminants in negative ion beams

Isobaric contaminants are often problematical in accelerated negative ion beams for research at certain radioactive ion beam (RIB) and accelerator mass spectrometry (AMS) facilities since their presence in low-intensity rare isotopic beams seriously compromise experimental results. This article describes a non-resonant, laser-based photo-detachment apparatus for use at these facilities, which, according to calculations efficiently removes isobaric contaminants from these beams. The advantage of the system for isobaric contaminant removal over other systems proposed to date lies in its ability to efficiently capture easily transportable energetic negative ion beams with low, intermediate or high energy spreads by a superconducting solenoid magnetic field. The ability to change the diameter of captured beams by adjusting the magnetic field strength permits optimum control of the radial overlap of the laser/negative ion beam profiles over an extended interaction region under high vacuum conditions without retarding optical affect, collision-cooling or capture losses.     

TEPC壁对重离子束微剂量学测量及相对生物学效应计算的影响

组织等效正比计数器（TEPC）广泛应用于重离子束微剂量学测量,提供用于计算相对生物学效应（RBE）的基础数据。为研究TEPC壁对重离子束微剂量学测量及RBE计算的影响,在蒙特卡罗（MC）模拟中引入理想组织等效正比计数器（Ideal-TEPC）,精确计算得到碳离子束不同水等效深度处的微剂量学量及RBE。Ideal-TEPC和常规TEPC的计算结果表明：TEPC壁会使碳离子束产生较大的辐射场畸变,且会使TEPC测量结果及RBE计算结果产生较大偏差,该偏差随贯穿深度的增加而增大。将TEPC壁视为具有固定水等效厚度的水层可在数值上抵消TEPC壁对RBE计算的影响,但在展宽Bragg峰（SOBP）后端会产生过修正现象。Ideal-TEPC结合MC模拟能有效避免TEPC壁效应及TEPC壁引起的辐射场畸变对重离子束微剂量学量和RBE计算的影响。     

Fishbone Mode Excited by Deeply Trapped Energetic Beam Ions in EAST

This paper describes the fishbone mode phenomena during the injection of highpower neutral beams in EAST(Experimental Advanced Superconducting Tokamak).The features of the fishbone mode are presented.The change in frequency of the mode during a fishbone burst is from 1 kHz to 6 kHz.The nonlinear behavior of the fishbone mode is analyzed by using a prey-predator model,which is consistent with the experimental results.This model indicates that the periodic oscillations of the fishbone mode always occur near the critical value of fast ion beta.Furthermore,the neutral beam analysis for the discharge is done by using the NUBEAM module of the TRANSP code.According to the numerical simulation results and theoretical calculation,it can be concluded that the fishbone mode is driven by the deeply trapped energetic beam ions in EAST.     

Development of a “best representativity” method for experimental data analysis and an application to the critical experiments at the Toshiba NCA facility

For nuclear critical experiments, it is essential to certify similarities of the experiment with the objective of the actual reactor conditions or actual reactor equipment. To judge the applicability of the experimental data, the concept of a “representativity factor” has recently been adopted in the critical experiment field, particularly for fast breeder reactors and future reactor studies. In this study, we extended this concept to the design of a light water reactor system. We developed a new numerical evaluation method and a calculation system. The method is based on a linear combination of the sensitivity coefficient vector of an experiment in which the representativity factor to the target system is maximized to utilize experimental data effectively. Simultaneously, using the measurement data of critical experiments, the method enables us to evaluate calculation errors caused by errors or uncertainties of physical parameters. The derivation of the new calculation method is explained first. We then qualify it with a sample calculation, presenting numerical results for three kinds of critical experiments conducted at the Toshiba Nuclear Critical Assembly facility. Finally, the results are compared with those of an extended bias factor method to clarify the performance of the new method.     

核材料炸药化学爆炸条件下烟云源项的实验与仿真

为获取核材料化学爆炸事故烟云参数和气溶胶扩散规律,本文理论分析了核材料化学爆炸事故烟云扩散过程与机理,建立了基于CFD技术的烟云扩散数值仿真方法,并通过爆炸烟云外场扩散实验对该方法进行了验证。研究结果表明：CFD方法能实现烟云扩散的数值仿真;实验和仿真均显示小当量TNT爆炸高度远小于Church经验公式,宽度比例却增加;气溶胶颗粒在蘑菇云形态的双涡环烟云流场中分布不均匀,粒径大于50 μm的颗粒物大多位于烟柱中,而大部分可吸入颗粒物在烟云顶部聚集;气溶胶在烟云稳定前的驱散与沉降会改变其源项参数,以Operation Roller Coaster实验气溶胶积累质量分布为例的计算显示,空载释放率约为地面气化率的58%,可吸入比率由20%升高至31%,可吸入释放率约为18%。     

ACME试验台架典型小破口工况试验及数值分析

对我国首个大型非能动堆芯冷却系统整体试验台架（ACME）中的典型小破口事故进行了试验及数值分析。分析结果表明：在ACME上开展的典型小破口试验,其事故序列及试验现象符合预期;RELAP5数值分析的主要结果能较好地反映试验现象,与试验结果吻合良好;堆芯棒束区相间摩擦模型的选用对堆芯坍塌液位的计算有较大影响,在不同阶段选用不同的模型可使计算结果更好地与试验值相匹配。     

SPH simulation of liquid metal target dynamics

An implementation of the smoothed particle hydrodynamics (SPH) method to study the dynamics of liquid metal targets under the effect of high power proton beams is presented. The accuracy of the method is verified through the comparison of numerical simulations with experimental results on liquid mercury performed in ISOLDE/CERN. The results are in good agreement and allow to have a better insight on the physics of the phenomenon.     

Effects of m=0 Harmonics on Quasi-Linear Stage of m=1 Double Tearing Mode

Effects of tearing modes are inves shows that the effect of the m = 0 harmonics on the early quasi-linear stage of m = 1 double tigated. The numerical calculation with the harmonics m = 0 included the m = 0 harmonics on the mode is negligible in the linear stage. As the mode begins to grow nonlinearly, both the current and flow profiles are pinched due to the m = 0 harmonics. To make a comparison we also carry out the calculation with m = 0 harmonics turned off. The profiles of the total current, poloidal magnetic field, and poloidal shear velocity in the cases with or without the m = 0 harmonics are compared and discussed. In addition, the formation of a poloidal velocity shear is found and its mechanism is investigated.     

Current self-limitation in a transverse nanosecond discharge with a slotted cathode

A high-voltage transverse pulsed nanosecond discharge with a slotted hollow cathode was found to be a source of high-energy (few kV) ribbon electron beams.Conditions for the formation and extinction of electron beams were experimentally studied in discharges in helium at pressures of 1-100 Torr.It was found that interaction of fast electrons with a non-uniform electric field near the slotted cathode led to limitation of the magnitude of the discharge current.A physical model was developed to describe the discharge current self-limitation that was in satisfactory agreement with the experimental results.Some technical solutions that are expected to increase the upper current limits in transverse nanosecond discharge are discussed.