最新刊期
卷 42 ， 期 4 ， 2019
- “上海光源优化top-up模式，采用双腔探头精确测定注入束团电荷量，测量精度达0.03%。”摘要：BackgroundThe Shanghai synchrotron radiation facility (SSRF) is a third generation light source. It has been in operation for user experiment in decay mode since 2009. Meanwhile, the top-up operation is also under exploration in order to provide users with stable beam. A key technique for top-up mode is optimizing the injection efficiency by precisely controlling the injecting bunch charge. Therefore, it is essential to measure precisely the bunch charge at the high-energy transport line. The direct-current current transformers (DCCT) can measure the average beam current but can't measure the single bunch charge. Although the integrating current transformer (ICT) can measure the individual bunch charge, it is sensitive to different background noise with a resolution of less than 1% and even worse under low bunch charge case.PurposeThis study aims to improve the measuring resolution for the injected individual bunch charge by using cavity charge monitor.MethodsSince the cavity monitor has high sensitivity and high resolution, it will be used to extract the bunch charge information. Normally, the cavity monitor works at C-band frequency and the generated radio frequency signal (RF) has to be down-converted to intermediate frequency (IF) signal. Thus a dual-cavity monitor working at different frequencies was developed to realize the two RF signals self-mixing. Moreover, because of the limited signal sampling rate, the four channel signal splicing scheme with strict synchronous phase-locked sampling technique was addopted to further improve the sampling rate.ResultsThe experimental results show that IF signal amplitude is linear to the bunch charge quantity. Moreover, the test results presents the measuring sensitivity is better than 0.03%.ConclusionThe novel dual cavity bunch charge system works well and meets the requirement of injection bunch charge measurement.关键词：SSRF;Dual-cavity bunch charge monitor;Precise bunch charge measurement;Signal acquisition
- 317
- |
- 19
- |
- 0
发布时间：2024-10-25 - “在自由电子激光装置领域，上海软X射线自由电子激光装置实现了精确定时系统，满足加速器设备需求。”摘要：BackgroundThe Soft X-ray Free-Electron Laser (SXFEL) is the fourth generation light source. The timing system is the key subsystem of the accelerator which can provide accurate timing trigger signal for the devices.PurposeThis study aims to design a timing system which can totally meet the requirements of SXFEL facility operation.MethodsAccording to the physical requirements and system physical equipments allocation of SXFEL, the hardware design of the timing system was based on the high precision pulse generator to realize high precision timing signals. The machine protection system (MPS) interface circuit and photoelectric converter for long distance transmission were developed as well. Experimental Physics and Industrial Control Systems (EPICS) was employed to perform the network-based distributed remote control system.Results & ConclusionsThe system works stably and reliably during the on line operation. The test results show that the jitter time is less than 150 ps, satisfying accelerator's requirements for timing system.关键词：Timing;Pulse generator;EPICS;Photoelectric conversion
- 338
- |
- 23
- |
- 0
发布时间：2024-10-25 - “在凝聚态物质动力学研究领域，上海同步辐射光源BL08U线站采用X射线光子关联谱技术，设计了基于软X射线的光子关联谱装置，为分析材料动力学信息提供技术途径。”摘要：BackgroundX-ray photon correlation spectroscopy (XPCS) is a new technique for studying the small-scale relaxation dynamics of condensed matter by using the second order coherence of coherent X-ray scattering. It requires high coherence of incident light. The X-ray interference lithograph (XIL) beamline (BL08U) of Shanghai Synchrotron Radiation Facility (SSRF) uses elliptical polarization oscillator as light source, which has good coherence and high photon flux. It is suitable for the dynamics study of mesoscopic scale electrodes or magnetic micro-regions in ferroelectric and magnetic materials.PurposeThis study aims to design a set of photon correlation spectroscopy equipment based on soft X-ray.MethodsSoft X-ray from XIL of SSRF is used as coherent incident beam, and the secondary coherent light is collected, converted and amplified to perform autocorrelation operation. The effects of incident light energy and scattering angle on the scattering vector and period size of sample are discussed.ResultsWhen the spectral range is 90.5~93 eV and the hole diameter is 1 mm, the periodic scales of samples at different positions are 10~60 nm. The second-order correlation intensity function of detector arc region is deduced by using Gauss model, and it is used as a function of detection area, photon energy and time. The multiplicative noise of autocorrelation is suppressed by multilayer film polarization extinction.ConclusionThe development of this device provides a technical approach for better analysis of material dynamics information, and is of great significance.关键词：Soft X-ray;Photon correlation spectroscopy;Intensity correlation;Dynamics
- 330
- |
- 19
- |
- 0
发布时间：2024-10-25 - “上海光源硬X射线微聚焦光束线站的控制及数据采集系统均是在EPICS环境下开发的，但基于EPICS软件的荧光扫描系统无法满足荧光面扫描实验的一些特定要求。对此，采用了Bluesky与EPICS软件相结合的方法，基于Python语法结构设计了控制和数据采集系统，集成了运动控制、光强探测和荧光信号采集功能，实现了数据表格的实时显示、荧光图谱的绘制、自适应步长扫描和峰值数据自动计算、多个任意位置样品连续扫描和二维方形螺旋扫描等荧光面扫描相关技术。该系统使用户简单操作即可完成复杂的荧光面扫描，提高了实验灵活性和实验效率。”摘要：BackgroundThe control and data acquisition system of the Shanghai synchrotron radiation facility (SSRF) hard X-ray microfocus beamline station was developed in the experiment physics and industrial control system (EPICS) environment. The existing fluorescence mapping system using EPICS software does not meet some specific requirements of fluorescence experiments.PurposeThis study aims to flexibly realize complicated fluorescent mapping techniques for SSRF hard X-ray microfocus beamline.MethodsBluesky and EPICS software were combined to design and implement a control and data acquisition system based on Python grammar structure. Functionalities such as motion control, light intensity detection and fluorescence signal acquisition were integrated in this system.ResultsThis system realizes real-time display of detected data and fluorescence mapping, adaptive step-size scanning, automatic calculation of peak statistics, continuous scanning of different samples in any spatial positions and two-dimensional square-spiral mapping.ConclusionThis proposed system allows users to perform complex fluorescence mapping with simple operation. It greatly improves the flexibility and efficiency of the experiment.关键词：Fluorescence mapping;Data acquisition
- 325
- |
- 19
- |
- 0
发布时间：2024-10-25 - “上海同步辐射光源主信号源研究取得进展，采用锁相环和直接模拟合成技术，实现了500 MHz单频信号源，相位噪声达到-125 dBc/Hz@1 kHz和-132 dBc/Hz@1 kHz，满足高频系统性能要求。”摘要：BackgroundThe main signal source is an essential part of digital low level radio frequency (LLRF) control system. It is used not only to generate the highly stable reference signals, but also to produce the high precision working clock required by the control system of LLRF.PurposeThis study aims to develope a high performance frequency synthesizer for Shanghai Synchrotron Radiation Facility (SSRF) so as to ensure high frequency system performance.MethodsTwo different techniques: phase-locked loop (PLL) and direct analog synthesis were employed to obtain the 500 MHz single frequency main signal source. Performance was measured and compared with the existing main signal source.ResultsThe experimental results show that the phase noise is -125 dBc/Hz@1 kHz and -132 dBc/Hz@1 kHz respectively, both of them meet the performance requirements of the RF system of SSRF.ConclusionDirect analog synthesis can be used to produce main signal source for SSRF and achieve better performance.关键词：LLRF;PLL;Direct analog synthesis;SSRF
- 313
- |
- 19
- |
- 0
发布时间：2024-10-25 - “钍基熔盐堆核石墨损伤机制研究取得新进展，揭示了熔盐浸渗对核石墨微结构的影响，为高性能核石墨制备和TMSR安全可靠运行分析提供理论依据。”摘要：BackgroundNuclear graphite is easily impregnated by liquid molten salt under high pressure environment due to its porous structure, which will affect the mechanical properties of the nuclear graphite. In-situ real-time tensile synchrotron-based two dimensional X-ray diffraction (2D-XRD) plays an important role in exploring the interaction between graphite and molten salt.PurposeThis study aims to reveal the in-situ real-time interaction mechanism between IG-110 nuclear graphite and FLiNaK molten salt and the microscopic mechanism of material fracture under the external stress load.MethodsIn-situ real-time tensile synchrotron-based 2D-XRD at several fixed external forces, i.e., 0 N, 15 N, 21 N, 27 N and 32 N, were implemented to reveal the microstructure evolution of IG-110 nuclear graphite and FLiNaK salt during the tensile fracture process.ResultsDuring the tensile fracture process, the (002) diffraction peak of IG-110 nuclear graphite infiltrated with molten salt presents an obvious shift to a lower q, a gradually decreasing peak intensity and a gradually increasing full width at half maximum (FWHM). Meanwhile, the diffraction peaks of the FLiNaK salt also present a gradually decreasing peak intensity.ConclusionIn the process of tensile fracture, the larger the interlayer spacing, the worse the crystallinity of IG-110 nuclear graphite and FLiNaK salt are emerged.关键词：Thorium molten salt reactor;IG-110 nuclear graphite;Molten salt impregnation;In-situ tensile synchrotron- based two dimensional X-ray diffraction
- 337
- |
- 23
- |
- 0
发布时间：2024-10-25
SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
- “在无损检测领域，利用快中子层析成像技术，成功获取了模拟样件的三维结构分布，具备内部轻材料孔洞缺陷检出能力。”摘要：BackgroundWith the strong penetrability of fast neutrons, it is significant to use computed tomography(CT) neutron imaging to perform non-injury detection of large size samples. Fast neutron tomography is seldom performed because of the low efficiency of fast neutron detection and low signal to noise ratio of raw projected fast neutron image.PurposeThis study aims to fulfill non-injury detection of some big size samples by using fast neutron tomography technology.MethodsFirst of all, based on a pre-developed compact accelerator neutron source, a fast neutron tomography system was established. Then the raw projections of light and heavy material mixture sample from different angles were obtained. Fast neutron CT images were successfully reconstructed by algebraic reconstruction technique (ART) using the pre-processing projection.ResultsThe results show that the structure of the object consisting of copper and PTFE was clearly reconstructed and the flaws of different holes in light material were detected.ConclusionsThe fast neutron tomography can be realized by using small accelerator neutron source.关键词：Fast neutron;CT;Denoising;ART algorithm
- 330
- |
- 28
- |
- 0
发布时间：2024-10-25
ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
-
Design and simulation study of an online activity measuring detector for radioactive noble gases AI导读
“在核反应堆运行和核应急情况下，准确测量放射性惰性气体活度至关重要。研究人员设计了4π双叠层闪烁体探测器，通过β-γ符合测量实现不同核素的分辨及活度测量，为核反应堆运行状况监测和核应急预警提供重要参考。”摘要：BackgroundIn normal operation or emergency, nuclear reactor can produce radioactive noble gases, the main components are 85Kr, 133Xe, 135Xe and 41Ar. It is of great significance to monitor the radioactivity of these mixed noble gases accurately for the operation of nuclear power plant.PurposeThis study aims to develop a 4π phoswich scintillator detector to measure the radioactivity of noble gases in online model.MethodsThe 4π phoswich scintillator detector consists of a sampling chamber, an inner plastic scintillator chamber for β measurement, and a CsI scintillator chamber for γ measurement. The pulse shaping discrimination (PSD) method is developed to distinguish the events between β, γ and β-γ coincidence events. Based on GEANT4 simulation toolkit, the performance of the detector, including the detection efficiency is investigated.ResultsThe simulation results show that both 0.3 mm plastic scintillator layer and a 20 mm CsI layer are necessary for measuring the radioactivity of noble gases. The size of sampling chamber should not be larger than ø50 mm×50 mm. Under these conditions, the detection efficiency for the above nuclides can be up to 90%.ConclusionsAccording to the simulation results, a composed 2-layer scintillation detector is designed, and its detection and recognition capability for different inert gases is studied. The comparison of these characteristics with actual calibration is the crucial step for this device.关键词：Radioactive noble gases;Radioactivity measurement;4π phoswich scintillator detector;β-γ coincidence;GEANT4- 318
- |
- 25
- |
- 0
发布时间：2024-10-25 - “在材料表面分析领域，中国先进研究堆冷中子束建立的中子深度剖面分析系统，真空度和中子注量率优于其他设备，可同时测量6个样品，性能得到验证。”摘要：BackgroundNeutron depth profiling (NDP) is a non-destructive near-surface analysis technique and it is widely used in characterization of polymers, semiconductors, alloys, lithium ion battery materials, photoelectric materials and many other materials.PurposeThis study aims is to develop NDP system to obtain the depth profiles of several crucial light nuclides (e.g., 6Li and 10B) in nearly any substrate.MethodsBased on the cold neutron beam of China advanced research reactor (CARR), a NDP system was developed with vacuum reached 3.4×10-5 Pa and neutron flux rate of 4.8×108 cm-2∙s-1. The standard reference material (SRM-2137) sample was used to test the performance of this NDP system. The measured α-particle spectrum was calculated by the inversion iterative algorithm to obtain the depth profiles of crucial elements.ResultsThe experimental results show that the simulation results of SRM-2137 agree well with the experimental results. The maximum error is less than 4% at each layer of 5 nm thickness. The peak depth is very close to the reference value (188 nm). The depth accuracy is 0.53%.ConclusionsEstablished CARR-NDP system and relevant experiments and data analysis techniques have been verified. The system will be further applied to investigating the lithium ion batteries, multilayer films and high-temperature alloys, etc.关键词：Neutron depth profiling;CARR;Near-surface analysis
- 320
- |
- 21
- |
- 0
发布时间：2024-10-25 - “在数字信号处理领域，研究者提出了平均值阈值法，有效计算随机波形信号数字化基线，具有占用内存小、计算速度快、稳定性好等优点。”摘要：BackgroundAfter the analog-to-digital converter (ADC) conversion, the baseline drift caused by CR differential circuit always exists. It increases the complexity of digital baseline estimation algorithm, and affects the real-time and accuracy of online baseline.PurposeThis study aims to improve the average method for extracting the digital baseline algorithm of random waveform signals in real-time.MethodsAn improved method of nuclear pulse digital baseline named average threshold method that can be implemented in field-programmable gate array (FPGA) was proposed. A measured signal with undershoot was taken as simulation nuclear pulse signal by disassembling and splicing to obtain a new signal with a fixed baseline value.ResultsThe baseline obtained by the average threshold method was consistent with the splicing baseline value. This algorithm exhibited strong real-time tracking effect while the baseline was changing.ConclusionThe average threshold method for real-time extraction of random waveform signals digital baseline algorithm can effectively calculate the baseline with less memory occupation and quick speed. The baseline value processed by the algorithm is stable, has a strong follow-up effect.关键词：Nuclear signal with undershoot;Digital baseline;Average threshold method
- 320
- |
- 20
- |
- 0
发布时间：2024-10-25
NUCLEAR ELECTRONICS AND INSTRUMENTATION
- “在生物技术领域，科学家利用DNA折纸技术，成功实现了链霉亲和素分子的高分辨成像，为研究生物分子形貌和功能提供了新思路。”摘要：BackgroundThe strong non-covalent interaction between streptavidin (STV) and biotin has been applied to various fields including molecular biology, immunology and biotechnology. The unique binding ability of STV to biotin is closely related to its structure. The crystal analysis results show that STV is a tetramer protein. Atomic force microscopy (AFM) plays an important role in studying the structure and function of proteins because it can provide morphological information of individual biomolecules in liquid environment. However, resolving STV with high-resolution AFM imaging remains challenge due to the small size and soft property.PurposeThis study aims to obtain high resolution single molecule STV images by AFM.MethodsWith modified biotin location on DNA origami, the addressable DNA origami was employed to selectively fix STVs. Then, AFM was used for image processing of STVs.ResultsThe single-molecule STV image at high-resolution was obtained. The observed STV showed an "hourglass-shaped" structure which consisted well with its crystal structure. At the same time, we noted that the STV morphology was susceptible to the effect of the loading force, indicating that it may be related to the flexibility of STVs.ConclusionThe simple and convenient method will provide a new way for studying the morphology and function of biomolecules.关键词：Atomic force microscopy;Single-molecule;High-resolution imaging;Streptavidin;DNA origami
- 319
- |
- 18
- |
- 0
发布时间：2024-10-25 - “在C-ADS超导强流质子加速器研究中，专家基于实验平台，采用PLC、嵌入式Linux系统和EPICS，完成了超导腔失效补偿实验研究，为实际应用奠定基础。”摘要：BackgroundThe failure compensation of superconducting cavity directly affects the stability of the proton beam, which is the focus of the study on accelerator-driven superconducting proton accelerator (C-ADS).PurposeThis study aims to design and implement an experimental platform to explore the results of the failure compensation of superconducting cavity.MethodsBased on experimental physics and industrial control system (EPICS) with embedded Linux system, programmable logic controller (PLC) was employed as the input/output controller (IOC) to communicate with the low level radio frequency (LLRF) of the cavity via the network of EPICS to obtain experimental results.ResultsSimulated failure data was quickly searched in IOC database, and the calculation of the time length of failure compensation at each stage was verified.ConclusionsThis experiment realized the rapid detection of failure of superconducting cavity and the automatic compensation operation of other cavities, which laid the foundation for practical application in future.关键词：Injector-I;Superconducting cavity;Proton accelerator;Experimental study;EPICS
- 363
- |
- 19
- |
- 0
发布时间：2024-10-25
NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
- “在高温熔盐热工实验中，研究者探究了硝酸盐熔盐在圆管内的换热特性，建立了适用于高温熔盐的换热关联式，验证了其与经典关联式的符合性。”摘要：BackgroundWith advantages of large thermal capacity, good chemical stability, high temperature, molten salt has recently been widely used in concentrated solar thermal power plants, nuclear reactors, chemical engineerings, and other fields.PurposeThis study aims at the convective heat transfer characteristics and verifying the heat transfer laws of molten salt in a circular tube.MethodsFirst of all, a thermal experimental loop of Nitrate (KNO3-53%, NaNO2-40%,NaNO3-7%) was built as basic experimental facility. The turbulent convective heat transfer coefficient of molten salt in circular tube for fully developed was obtained by Wilson's correction method. Then the experimental results combining with the experimental data of five kinds of molten salt in the open literature were fitted to get the experimental correlation of molten salt in the range of 10 000<Re<50 000 and 4<Pr<26 for the turbulent flow in the round tube. Finally, comparisons of different kinds of molten salt with classical correlation Dittus-Boelter correlation, Sieder-Tate correlation, Hausen correlation and Gnielinski correlation were conducted.ResultsThe experimental data of molten salt agree well with the existing known relationship, and the deviation was below 25%.ConclusionThe results show that the heat transfer characteristics of the molten salts still conform to the classical heat transfer relationship.关键词：Molten salt;Turbulent flow;Forced convection;Convective heat transfer;Correlation
- 318
- |
- 20
- |
- 0
发布时间：2024-10-25 - “在熔盐环境中，高剂量辐照导致镍基合金表面孔洞和Cr元素流失，硬度降低。”摘要：BackgroundUNS N10003 alloy is considered to be the primary option of metal structural materials for the molten salt reactor (MSR). It will be affected by the extreme environments, i.e. high temperature, high neutron doses and corrosive coolant during the operation of MSR. Considering that the safe operation of MSR will mainly depends on the service performance of structural alloys, it is necessary to evaluate the performance of such kind of alloys in the complicated environments.PurposeThis study aims at understanding the effect of He bubbles on the corrosion properties of UNS N10003 alloy in molten salt environment.MethodsFirst of all, the 1.2 MeV high temperature He ion irradiation was performed on the UNS N10003 alloy at 650 oC. The irradiation fluence was set up to 5×1015 ions∙cm-2 and 5×1016 ions∙cm-2 respectively. Then, samples were immersed in a dry high-purity graphite crucible filled with 200 g FLiNaK salts and heated to 650 oC for 200 h. Finally, scanning electron microscopy (SEM) and transmission electron microscope (TEM) were employed to investigate the surface morphology, the distribution of elements and the microstructure, respectively. Nano-indentation technique was used to obtain the hardness.ResultsAt the dose of 5×1015 ions∙cm-2, there was not obvious difference in the surface morphology and distribution of element distribution of the corroded alloy with and without irradiation. While for the corroded alloy pre-irradiated with He ions at the dose of 5×1016 ions∙cm-2, large amount of holes were observed on the surface and the loss of Cr element was found from the bulk to the surface, which can be ascribed to the He bubbles formation. The hardness of irradiated alloy, corroded alloy, and corroded alloy pre-irradiated was 4.12 GPa, 2.65 GPa and 3.16 GPa, respectively.ConclusionHe bubbles formation play an important role on increasing the corrosion of UNS N10003 alloy. The hardness of irradiated and corroded alloy is lower than the irradiated alloy, and higher than of the corroded alloy. It is a combined effect of irradiation and corrosion.关键词：Nickel based alloy;Ion irradiation;Molten salt corrosion;He bubbles
- 338
- |
- 20
- |
- 0
发布时间：2024-10-25 - “在液态重金属反应堆领域，专家基于有限元方法，分析了地震响应，为结构安全设计提供依据。”摘要：BackgroundCompared with the traditional pressurized-water reactor (PWRs) with low density coolant and loop layout, the lead-based reactor uses liquid heavy metal coolant and has the characteristics of pool layout.PurposeThis study aims at the impact and vibration modes of heavy metal coolant's sloshing to the reactor vessel and its internal components under a load of seismic.MethodsFirst of all, two-way fluid-structure coupling finite element method was applied to the seismic response analysis of liquid heavy metal reactor. Then the sloshing effect of coolant type, the support form, as well as the height-diameter ratio on the sloshing effect of coolant in the reactor container, were calculated and analyzed.ResultsThe calculation results show that the seismic response of liquid heavy metals is not equal to that of light coolant, and the fluid-dynamic viscosity is not significant for fluid-solid coupling of large-scale reactors. The different support forms have stress concentration at the support position and the overall performance is that the beam mode is not sensitive to the support form. The vibration modes stimulated by different liquid-filled ratios are similar, and the smaller the liquid-filled ratio, the more concentrated the maximum stress intensity point are on the bottom head.ConclusionThese results provide a parametric basis for the structural safety design of liquid heavy metal reactors.关键词：Liquid heavy metal reactor;Coolant sloshing;Pool structure;Seismic response;Fluid-structure interaction
- 314
- |
- 18
- |
- 0
发布时间：2024-10-25
NUCLEAR ENERGY SCIENCE AND ENGINEERING
- Address：2019 Jialuo Road, Jiading, Shanghai, China Postal code：201800
- Tel：021-39194977 Email：LHB@sinap.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 沪ICP备05005479号-1
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：740042 Visits Today：784
0