数字辐射成像系统阵列探测器成像变形分析

在数字辐射系统(DR)如60Co集装箱检测系统(TC-SCAN系统),采用圆弧形和直线(折线)形两种形式的线探测器阵列,分析了两种探测器阵的成像变形,设计了削减这种变形的算法并在TC-SCAN集装箱检测系统中取得较好的应用.     

Development of HL-2M data integration and acquisition system for magnetic diagnostics

Magnetic measurement and diagnostics are critical for the operation of magnetic confinement experimental facilities and plasma analysis,while differential signals are mostly detected by a detector.For this,we have developed and designed a stable and reliable data integration system for HL-2 M magnetic measurement and magnetic diagnostics.The system will be used for realtime control of HL-2 M after the construction of HL-2 M is completed.The system is built based on the PXI platform,and the software system is based on the LABVIEW platform.Key technologies realized by the system primarily include drift compensation,pulse data acquisition technology,multi-threading processing technology and transmission control communication protocol.Trials of the system were successfully carried out on HL-2 A,and the results showed that the system could fully meet the construction needs of HL-2 M.     

多道脉冲幅度分析中的数字基线估计方法

介绍了用于多道脉冲幅度分析的数字基线估计方法的基本特点,利用泛函变分方法推导了最小噪声基线滤波器的计权函数．利用Fourier变换导出了数字基线估计的频率响应,探讨了参数取值对其幅频特性的影响。还利用MATLAB模拟了电荷灵敏前置放大器输出的噪声电压信号,验证了最小噪声数字基线估计的处理效果。研究结果表明,数字基线估计方法能实现最佳基线估计,特别适于在数字化多道脉冲幅度分析中使用。     

Thermal-hydraulic analysis of the HL-2M divertor using an homogeneous equilibrium model

The heat flux of the HL-2M divertor would reach 10 MWm-2 or more at the local area when the device operates at high parameters.Subcooled boiling could occur at high thermal load,which would be simulated based on the homogeneous equilibrium model.The results show that the current design of the HL-2M divertor could withstand the local heat flux 10 MW m-2 at a plasma pulse duration of 5 s,inlet coolant pressure of 1.5 MPa and flow velocity of 4 m s-1.The pulse duration that the HL-2M divertor could withstand is closely related to the coolant velocity.In addition,at the time of 2 min after plasma discharge,the flow velocity decreased from 4 m s-1 to 1 m s-1,and the divertor could also be cooled to the initial temperature before the next plasma discharge commences.     

DAMPE-PSD读出电子学研制

暗物质粒子探测卫星(dark matter particle explorer, DAMPE)是我国空间科学卫星系列的首发星,用于找出可能的暗物质粒子信号。塑料闪烁体阵列探测器(plastic scintillator detector, PSD)分系统作为卫星有效载荷的主体部件之一,参与承担高能粒子电荷测量和电子/γ射线鉴别任务。PSD由82根塑料闪烁体条和164个光电倍增管（photomultiplier tube, PMT)组成,有328个输出通道,每根塑料闪烁体条的动态范围为2×103,需配备1套完备的读出电子学系统。该电子学系统由4块前端电子学（front-end electronics, FEE）板构成,共具有360个信号处理通道,总功耗6 W。电路主要包括电荷测量电路、模拟调理电路、模数变换电路、刻度电路、环境监测电路、FPGA电路、电源管理电路以及接口电路等,其主要功能是基于32路模拟信号将PMT的电荷信号输入VA160 ASIC芯片,考虑了抗辐照加固、温度设计等一系列关键问题,以确保在严酷的太空中具有长期的可靠性。测试结果表明,该FEE系统工作稳定、性能良好,具有较好的技术指标,每个电子学通道实现了0～12.5 pC的动态范围,通道的随机噪声水平好于2 fC,积分非线性好于0.6%。FEE能适应恶劣的空间环境,具有很高的可靠性。FEE配合PSD样机还分别于2014年和2015年在欧洲核子中心（CERN）的PS和SPS终端成功完成了2次束流试验,验证了PSD的探测能力完全满足任务书中提出的功能和指标要求,能很好实现实际科学任务需求。     

基于信号功率谱梯度分析的n-γ甄别方法研究

发现了液体闪烁体探测器在分别与中子和γ射线作用时输出脉冲的功率谱梯度存在较大差异这一特征,由此提出一种基于脉冲信号的频域特征参数来甄别中子和γ射线的方法--功率谱梯度分析（SGA）法。本文论述了SGA法的基本原理及其可行性,并通过伴随粒子中子飞行实验验证了SGA法n-γ甄别结果的正确性。研究了SGA法在采样率从5 G/s逐步递减到250 M/s下甄别性能的变化。结果表明,与基于时域特征的n-γ甄别方法相比,SGA法对噪声较不敏感,抗干扰能力强,甄别性能更为稳定且计算量小。     

keV能区中子注量率测量初级标准装置研制

由于大多数中子探测器在keV能区处于共振能区,截面数据无法精确已知,无法作为中子注量率测量初级标准装置。⁶Li在keV能区的截面精确已知,本文以此设计了一种包含⁶LiF转换体的硅半导体探测器系统（LiF-SSD探测器）,建立了keV能区中子参考辐射场中子注量率测量初级标准装置。利用SRIM和TRIM程序估算了LiF-SSD探测器的计数率;基于Geant4开发了探测器响应计算程序,给出了中子能量为27.4 keV的探测器脉冲幅度计算谱;利用⁴⁵Sc(p,n)-⁴⁵Ti反应,测量了27.4 keV中子能量点的探测器脉冲幅度谱,测量结果与理论计算谱符合较好。     

Development of the real-time double-ring fusion neutron time-of-flight spectrometer system at HL-2M

A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII system is in its development stage,and this work describes its characteristics in terms of design principle,system structure,electronic system design,preliminary tests,and neutron transport simulation.The preliminary test results illustrate that the TOFII system can demonstrate the realtime dynamic spectrum every 10 ms.The results also show that based on the support vector machine method,the n-γdiscrimination algorithm achieves the discrimination accuracy of 99.1%with a figure of merit of 1.30,and the intrinsic timing resolution of the system is within 0.3%.The simulated flight time spectrums from 1 to 5 MeV are obtained through the Monte Carlo tool Geant4,which also provide the reasonable results.The TOFII system will then be calibrated on mono-energetic neutron sources for further verification.     

BaF2闪烁体探测器信号数字化方法研究

应用数字化方法对BaF₂闪烁体探测器脉冲信号进行了研究,信号的测量通过FADC和计算机系统实现,并对所采集的脉冲波形进行了离线分析。通过计算脉冲波形的面积提取了射线的能量信息,重建了能谱,并与传统电子学模拟信号测量方法得到的能谱进行了比较;应用过阈定时方法提取了脉冲的时间信息,测量并给出了4πBaF₂探测器系统的时间分布谱;应用脉冲形状甄别法对α粒子和γ射线进行了鉴别研究,根据脉冲信号快/慢成分比的差别清楚地将α粒子从γ射线中鉴别开来。本工作为在γ全吸收型4πBaF₂探测器系统中应用FADC进行多通道、多参数、大数据量数字化数据获取积累了经验。     

Design of the HL-2M power supply control system

The power supply control system is one of the most important local control systems of HL-2M tokamak. The power supply system of HL-2M is composed of four flywheel generator sets with total capacity of 600 MVA, all the magnetic field coil power supplies and high voltage power supplies of auxiliary heating system. The control system of power supply should make sure the large amount of on-site equipment and facilities to operate steadily and reliably.This paper presents the architecture of HL-2M control system and four kinds of established control networks. It describes how the power supply control system is built by using the established hardware structures and software agreements. Specially, it is focused on introducing an application of real-time technology based on the reflective shared memory and the fully digital compact solution for controlling the high power converters. Otherwise, a scheme which adopts PROFINET and Sequence of Events technology to carry out the intellect interlock control system is given.     

早稻田大学皮秒脉冲辐解装置

A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University. The laser pulse is used for excitation of the photocathode and for generation of white light, which is used for analyzing light in the pulse radiolysis.The system design is shown in Fig. 1. For absorption spectroscopy with wide wavelength region, the white-light continuum was used as analyzing light. The white light continuum was generated by focusing the high intense IR laser into the water cell. The available wavelength was 400-950 nm. Typical data obtained is shown in Fig.2 by using the system. We have performed a deconvolution technique to know the time resolution of our system. For this purpose, we have assumed the shapes of the electron pulse and the laser pulse as Gaussian distributions. Furthermore, the difference of velocity in a sample cell between the electron pulse and the laser pulse due to the refractive index of a sample was also taken into consideration and assuming that the hydrated electrons are formed as a step function and the response function is Gaussian.Thus, time resolution of the system was estimated by deconvolution of the experimental data.We have achieved a time resolution of about 26ps by measuring time profile of hydrated electrons in H2O.     

车辆核材料探查仪器γ探测器设计研究

阐述了核材料探查仪器的报警阈与调查水平、漏报率和误报率之间的关系.利用蒙特卡罗方法计算了不同厚度塑料闪烁体的探测效率,确定了选择车辆探查仪器几何尺寸的方法.     

卡钳式脉冲电流探测器研究

介绍了一种卡钳式、脉冲电流探测器的研制情况,给出了原理与结构。详细介绍了该探测器的特点和特性参数,同时还给出了探测器的灵敏度、频谱等标定数据以及在实验中的使用情况等。     

组合PIN脉冲中子探测器的能量响应

组合PIN脉冲中子探测器由一对PIN半导体和中子辐射体组成。理论计算了CH2和^235U分别作为中子辐射体的组合PIN脉冲中子探测器的灵敏度随中子能量的变化;用脉冲中子源实验测量了由CH2辐射体组成的探测器的14MeV中子灵敏度,实验结果与计算符合很好。     

脉冲中子煤炭工业分析仪实验系统的研制

应用脉冲快热中子分析技术(PFTNA)代替煤炭行业原来使用的化学分析方法,不但节约成本,而且经过努力可以实现在线分析,是一种非常有前途的分析方法。东北师范大学辐射技术研究所应用自己的特色产品——5×10~8n/s脉冲中子发生器和上海硅酸盐研究所生产的锗酸铋(BGO)探头建立了脉冲中子煤炭工业分析仪的实验系统,已取得了一些成果,其中C、H、O、灰分的质量精度分别达到0.5％、0.4％、7.0％和5.9％。     

数字辐射扫描成像系统水平分辨率的提高

对辐射成像无损检测系统中的水平采样模型和模糊影响进行了分析，提出重叠采样提高水平扫描分辨率的方法，并通过实验测量水平冲击响应函数，利用逆滤波算法对采样模糊后的图像进行了恢复。     

Investigation on the Fatigue Characteristic in Support Structure of HL-2M Tokamak

In order to obtain enhanced plasma parameters a complete new tokamak HL-2M is now under construction in Southwestern Institute of Physics. To assure the structural safety of the device for the entire operation cycle, one of the most important issues is the lifetime-limiting effects due to the pulsed operation mode. Fatigue is one of the major failure modes to be considered in mechanical design, and pulsed operation imposes stress with significant alternating components on the support structure （SS）. Therefore, the reliability of the whole device is strongly affected by the stress and fatigue characteristic of the SS as the interface structure. This article introduces the SS design and details the fatigue life calculation methods based on the different characteristics of the sub-structures. The fatigue life in hazardous areas of the toroidal field coils anti-torque structure （TFCs-ATs） has been determined by non-linear analysis results. And with the stress- time history data of the vacuum vessel ＆ poloidal field coils support structure （VV＆PFCs SS）, the fatigue analysis of the hot spots has been completed based on rain-flow counting method and linear cumulative damage method. The calculated minimum fatigue life on TFCs-ATs and VVSzPFCs SS is 4.743E＋05 and 1.805E＋06 cycles, respectively. And the calculated fatigue life on sub-structures can meet the required life for HL-2M tokamak： 1.0E＋05 cycles.     

Stress and Thermal Analysis of the In-Vessel RMP Coils in HL-2M

A set of in-vessel resonant magnetic perturbation(RMP) coils for MHD instability suppression is proposed for the design of a HL-2M tokamak.Each coil is to be fed with a current of up to 5 kA,operated in a frequency range from DC to about 1 kHz.Stainless steel(SS) jacketed mineral insulated cables are proposed for the conductor of the coils.In-vessel coils must withstand large electromagnetic(EM) and thermal loads.The support,insulation and vacuum sealing in a very limited space are crucial issues for engineering design.Hence finite element calculations are performed to verify the design,optimize the support by minimizing stress caused by EM forces on the coil conductors and work out the temperature rise occurring on the coil in diferent working conditions,the corresponding thermal stress caused by the thermal expansion of materials is evaluated to be allowable.The techniques to develop the in-vessel RMP coils,such as support,insulation and cooling,are discussed.     

低本底伽马能谱仪闪烁探测器的智能化温控系统设计

为了消除环境温度对闪烁体相对光输出影响带来的谱线漂移问题,设计了一种新型智能化温控系统。设计专用循环水路,采用改进的PID控制算法实时调整制冷加热模块输出电流,完成温度采集、控制操作,实现对闪烁体探测器的恒温控制。系统可通过CAN总线或USB接口与主机控制器进行数据交互,兼容现有能谱仪。经试验可知,温控系统温度稳态误差小于0.5℃,核素特征峰基本无漂移,满足稳谱使用要求,具有较高的应用价值。     

Design of the stripping unit and the electromagnetic analysis unit for the E//B NPA on HL-2A/2M tokamak

An E//B neutral particle analyzer is under development for fast ion diagnosis on HL-2A/2 M tokamak. The stripping unit is composed of a stripping room (equipped with two differential tubes and a gas supply bellows), a vacuum chamber and a vacuum pumping system. The stripping efficiency of the stripping room is calculated in the form of global efficiency R × f₊₁, where R is the non-scattered-away rate and f₊₁ is the fraction of charge state +1. The magnetic field of the E//B analyzer is produced with a permanent magnet. The yoke and the poles of the magnet are made of mild steel and the magnet plates are made of NdFeB. The magnetic poles are specially designed to focus the ion trajectories and to increase the use rate of the magnet. The shape of the magnet and the electric plates are carefully designed so that the ions are dispersed into two lines of H⁺ and D⁺ on the detector plane. For each line, the energy increases from 10 to 200 keV from one side to another.