基于束流环形高斯模型对上海硬X射线自由电子激光装置的束流刮束器进行活化分析

在建的上海硬X射线自由电子激光装置(Shanghai HIgh repetition rate XFEL aNd Extreme light facility,SHINE)的加速器隧道内,采用束流刮束器刮掉束晕外围张角比较大的电子,刮束器的束流损失率为0.1‰。本文采用蒙特卡洛程序FLUKA,用SOURCE程序实现电子束在3σ_beam外的高斯分布,以尽量真实模拟电子在束流刮束器处的丢失情况,解决了低功率刮束情况下蒙特卡洛模拟无统计性结果的难题。利用束流环形高斯模型对刮束器的活化进行了分析,结果表明环形高斯模型可以更真实地再现电子在束流刮束器的丢失情况;5年运行后距刮束器30 cm处的剩余剂量率达到了数百μSv/h至数mSv/h,和国外类似装置计算结果相当;通过对放射性核素的种类分析,结果证明刮束器(钨)的放射性废物处置难度不大。     

上海软X射线自由电子激光腔式束流位置测量系统

上海软X射线自由电子激光装置（Shanghai Soft X-ray Free Electron Laser, SXFEL）需1个分辨率达到亚μm量级的束流位置测量系统,并采用基于束流准直的方法实现波荡器段电子束与光子束的紧密重合。为此设计研制了1个由C波段腔式探头、单路混频至低中频的射频前端以及自主研发的专用数字信号束流位置处理器（digital beam position monitor processor, DBPM）构成的腔式束流位置测量（cavity beam position monitor, CBPM）系统。本文对系统的设计、软硬件结构、系统搭建进行了介绍,并基于漂移段搭建的3个紧邻的CBPM阵列完成了在线系统性能评估。束流实验结果表明,在束团电荷量为500 pC、系统动态范围在±800 μm的条件下,位置分辨率可达880 nm,这也是国内首次研制成功可在线运行的具有亚μm位置分辨率的CBPM系统。此外,采用CBPM的相位腔进行相对束团电荷量、束团到达时间的测量,其性能评估结果也均优于SXFEL设计要求。     

用于自由电子激光装置的丝扫描束流横向截面测量系统原型机

基于丝扫描系统的束流横向截面测量为半阻拦式的测量方法,相比于截面靶测量对束流影响较小。上海高重复频率硬X射线自由电子激光装置(SHINE)束团截面在线测量系统计划采用丝扫描技术实现,为此设计研制了由丝靶探头、机械运动机构、束损探测器、电子学系统构成的丝扫描束流横向截面测量系统原型机。本文介绍了该原型机的工作原理、具体设计及在丝扫描探头上游安装腔式束流位置测量(CBPM)系统进行束流中心位置和束团电荷量精确补偿的优化方案。为精确评估该样机系统性能,在上海软X射线自由电子激光(SXFEL)中相邻位置布局了丝扫描探头和YAG靶截面探头,通过同时测量并对比同样束流截面的方法,对丝扫描系统原型机性能进行了束流实验评估。束流实验结果表明,在束团电荷量500 pC、电子能量0.84 GeV的条件下,丝扫描技术可用于电子束团的在线半阻拦式截面测量,测量不确定度好于30μm,测量结果与SXFEL装置标配的YAG靶截面靶测量系统结果一致。     

强激光与固体靶相互作用所致硬X射线剂量的蒙特卡罗模拟

本文利用蒙特卡罗程序FLUKA建立了强激光与固体靶相互作用所致硬X射线剂量估算模型,通过与文献结果进行比较,对计算模型进行了验证。利用该计算模型研究了不同电子温度、不同靶材料(包括金、铜和聚乙烯3种常见靶材)和厚度对X射线剂量的影响。计算结果表明,X射线剂量与电子温度密切相关,并会受到靶参数的影响。相同靶厚情形下,Au靶产生的X射线剂量约为Cu靶产生的X射线剂量的1.2倍,约为PE(聚乙烯)产生的X射线剂量的5倍。另外,相较于其他靶厚,当选取电子的平均射程为靶厚时,产生的X射线剂量较大。这些计算结果将为强激光装置中电离辐射剂量的评估提供相关参考。     

超短脉冲激光与固体靶相互作用的硬X射线能谱

本实验使用高纯锗探测器，运用单光子法，对超短脉冲激光与固体铜靶相互作用产生的硬X射线能谱进行测量。实验结果表明：在激光强度I≈8×10¹⁶W/cm²的P极化光以45°入射角照射5 mm铜靶、探测立体角为4.5×10^－6的实验条件下，产生的硬X射线的能量主要集中在低于100keV能量范围内，超热电子温度分别为(7.4±0.7)keV和(19.5±1.6)keV。     

用于HL-2A装置的新型硬X射线探测器

介绍了一种应用于托卡马克等离子诊断领域的新型硬X射线探测器,该探测器主要由硅酸钇镥(Lutetium-yttrium Oxyorthosilicate,LYSO)闪烁体和硅光电倍增管(Silicon Photomultiplier,Si PM)组成。基于项目应用需求,对探测器的选型和基于粒子输运蒙特卡罗仿真软件GEANT4的探测器设计加以阐述,并搭建了前端的探测系统,在HL-2A托卡马克装置上进行了现场诊断实验。实现了硬X射线空间能谱和辐射强度分布的诊断测量。实验表明该探测器阵列具有10 ms的时间分辨率,同时具有结构紧凑、使用方便等特点,能够满足等离子体诊断中硬X射线动态能谱和强度分布测量的诊断需求。     

校准用X射线装置的微机参量控制

论述了核工业华北放射性计量站利用计算机技术实现自制Ｘ射线校准装置参量控制的方法。     

中能X射线自由电子激光SASE脉冲在Cr/B4C多层膜结构上的反射特性

反射光学元件是X射线自由电子激光(Free Electron Laser,FEL)光束线上非常重要的器件,而FEL通常通过自放大自发辐射模式(Self-Amplified Spontaneous Emission,SASE)出光.多层膜结构,尤其是Cr/B4C多层膜结构,在中能X射线范围内具有优越的光学性能.利用GEN...     

SHINE束线站定时系统束团编号的数据采集

上海硬X射线自由电子激光装置（Shanghai High Repetition rate XFEL (X-ray Free Electron Laser) and Extreme light facility,SHINE）是一个高重频XFEL装置,束线站定时系统需要为设备提供基于硬件的精确的X射线束团编号和定时触发。对于SHINE束线站单脉冲工作模式的设备,采集数据包以及对应时刻的束团编号信息,便于后续实验数据分析。设计了一个束团编号采集的测试系统,它基于Zynq-UltraScale+型片上系统（System-On-Chip,SOC）搭建,采用了白兔协议（White Rabbit）协议的定时系统环境。该测试系统通过FPGA夹层卡（FPGA Mezzanine Card,FMC）获取嵌入型从节点的束团编号,使用LwIP(Light weight Internet Protocol)协议搭建的TCP协议栈实现束团编号的采集。采用Basler相机对该系统进行了实验测试,并使用pypylon库来采集相机的数据。实验测试结果表明：该束团采集测试系统获得的束团编号数量和图像帧数相同,可以满足SH...     

强激光与固体靶相互作用所致硬X射线的辐射安全初步研究

激光技术的迅速发展使得国际国内涌现出一批强激光装置,而这些装置中强激光与固体靶相互作用所致硬X射线产生的辐射危害也逐渐被人们发现和重视.通过广泛的调研,对强激光与固体靶产生硬X射线的物理过程及其源项特点进行了分析和讨论,包括激光到电子的能量转换效率,热电子能谱和电子温度,以及热电子所产生硬X射线的能谱等,并且得到了激光强度在1014到1020 W/cm2之间的激光与靶相互作用后,产生的X射线剂量的初步评估结果.最后以斯坦福直线加速器中心(SLAC)的一个强激光装置为例,介绍了其辐射安全系统的初步设计.研究结果为强激光装置的辐射安全评估及其安全系统设计提供了相关参考.     

Manufacturing prototypes for LIPAC beam dump

The purpose of the research is to define the most adequate manufacturing process for the dump of a linear deuteron accelerator. The deuteron beam can be pulsed as well as continuous with energies up to 9 MeV. The maximum beam power is 1.12 MW corresponding to a beam current of 125 mA.The requirements on the surface on which the deuterons will be stopped are quite demanding and the length and slenderness of the cone poses a considerable difficulty in the manufacturing process.The design of the beam dump is based on a copper cone 2500 mm long, 300 mm aperture and 5 to 6.5 mm thickness.Basically only two technologies were found feasible for the manufacturing of the cone: Electroforming and Electron Beam Welding (EBW).The article shows the main results found when manufacturing different prototypes.     

Corrosion and activation analysis of the LIPAC beam dump cooling circuit

The LIPAC beam dump cooling circuit has been modelled by means of TRACT (TRansport and ACTivation) code. TRACT simulates the flow and isotope transport inside a network of 1-D channels. The cooling circuit consists of the beam dump (inner cone and shroud made of EDP Cu (electrodeposited copper) and the cylinder made of SS304L), the piping from the cooling skid to the beam dump cell and the cooling skid itself composed of the heat exchanger, the purifying loop and the pump. Corrosion is an issue that deserves attention because of radioprotection reasons and because it could affect the cartridge thermomechanical performance. A simulation with TRACT for a water pH of 7 at the beam dump entrance has been performed, showing corrosion rates (< 1 g/(m² year)) which do not compromise the beam dump performance.     

Design of a beam dump for the IFMIF-EVEDA accelerator

The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA cw deuteron accelerator prototype for verifying the validity of the accelerator design for IFMIF. A beam stop will be used for the RFQ and DTL commissioning as well as for the EVEDA accelerator tests. Therefore, this component must be designed to stop 5 MeV and 9 MeV deuteron beams with a maximum power of 1.13 MW.The first step of the design is the beam-facing material selection. The criteria used for this selection are low neutron production, low activation and good thermomechanical behavior. In this paper, the mechanical analysis and radioprotection calculations that have led to the choice of the main beam dump parameters will be described.The present design is based on a conical beam stop (2.5 m length, 30 cm diameter, and 3.5 mm thickness) made of copper plus a cylindrical 0.5 m long beam scraper. The cooling system is based on an axial high velocity flow of water. This design is compliant with the mechanical design rules during full power stationary operation of the accelerator. The radioprotection calculations performed demonstrate that, with an adequate local shielding, doses during beam on/off phases are below the limits.     

Activation analysis of the water cooling system of the LIPAc beam dump

LIPAc stands for Linear IFMIF Prototype Accelerator. LIPAc generates a 9 MeV deuteron beam, which is stopped at a beam dump, depositing over 1 MW of thermal power. A water cooling system has been devised for extracting this energy while keeping operational temperatures within range. The existing high neutron fluxes in the beam dump during operation produce activation of both coolant and beam stopper, which also suffers from corrosion into the coolant. The presence of radioisotopes in the cooling water leads to a radiological hazard.Water purification systems are located outside the accelerator vault and accumulate activated products during filtration, requiring a specific radiological shield to comply with target dose rates. Also devices containing large volume of activated cooling water, like N-16 decay pipes, require specific radioprotection analysis and design. This work identifies the most relevant radiation sources due to the activated cooling fluid, which may result in radiation doses to workers, and propose radioprotection measures into the design to mitigate their effect.     

Analysis of fuel management in the KIPT neutron source facility

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of an experimental neutron source facility consisting of an electron accelerator driven sub-critical assembly. The neutron source driving the sub-critical assembly is generated from the interaction of 100 KW electron beam with a natural uranium target. The sub-critical assembly surrounding the target is fueled with low enriched WWR-M2 type hexagonal fuel assemblies. The U-235 enrichment of the fuel material is <20%. The facility will be utilized for basic and applied research, producing medical isotopes, and training young specialists. With the 100 KW electron beam power, the total thermal power of the facility is ∼360 kW including the fission power of ∼260 kW. The burnup of the fissile materials and the buildup of fission products continuously reduce the system reactivity during the operation, decrease the neutron flux level, and consequently impact the facility performance. To preserve the neutron flux level during the operation, the fuel assemblies should be added and shuffled for compensating the lost reactivity caused by burnup. Beryllium reflector could also be utilized to increase the fuel life time in the sub-critical core. This paper studies the fuel cycles and shuffling schemes of the fuel assemblies of the sub-critical assembly to preserve the system reactivity and the neutron flux level during the operation.     

Design optimization of 3.9 GHz fundamental power coupler for the SHINE project

The third harmonic superconducting cryomodule is being designed for the Shanghai High repetition rate XFEL and Extreme light facility(SHINE)project,which is under construction.In contrast to the European X-ray Free Electron Laser(E-XFEL)project,the 3.9 GHz cryomod-ules in the SHINE project will operate in the continuous wave regime with higher radio frequency average power for both cavities and couplers.We propose a 3.9 GHz fundamental power coupler with an adjustable antenna length,for satisfying the SHINE project requirements.Here,we describe the 3.9 GHz fundamental power cou-pler's design considerations and power requirements for various operating modes of the SHINE Linac.We also present the results of the radio frequency simulation and optimization,including the studies on multipacting and thermal analysis of the proposed 3.9 GHz coupler.     

酒类专用辐照站的设计

本文扼要介绍了酒类专用辐照站的设计原则、物理方案、工艺流程、建筑结构及其安全特性。该辐照站现装钴源0.925×10~(15)Bq,辐照酒量每天10t。它结构简单,操作方便,安全可靠,射线利用率高,很适于在地方小企业推广应用。     

Evaluation of neutron beam characteristics for D-BNCT01 facility

An accelerator-based Boron Neutron Capture Therapy （AB-BNCT） experimental facility called D-BNCT01 has been recently completed and is currently able to generate a high-intensity neutron beam for BNCT-related research.In this study,we perform several experiments involving water phantoms to validate the Monte Carlo simulation results and analyze the neutron beam characteristics.According to our measurements,D-BNCT01 can generate a neutron flux about 1.2×10⁸n/cm²/s at the beam...     

离子束分析技术在抗核加固研究中的应用

本文介绍了核辐射使电子元器件失效的机制以及离子束分析技术在抗核加固研究中的若干应用。