一种测量辐射加工用加速器电子束能量的方法

根据射程法原理,在上海二级标准剂量学实验室对辐射加工用加速器电子束能量的测量方法进行了实验研究,并在3个辐射工厂对3台3MeV、20mA高频高压型加速器的电子束进行了能量测定.结果表明,在1-3MeV能量范围内,能量测定准确度优于±10%.     

High-flux electron beams from laser wakefield accelerators driven by petawatt lasers

Laser wakefield accelerators (LWFAs) are considered to be one of the most competitive next-generation accelerator candidates.In this paper,we will study the potential high-flux electron beam production of an LWFA driven by petawatt-level laser pulses.In our three-dimensional particle-in-cell simulations,an optimal set of parameters gives ～40 nC of charge with 2 PW laser power,thus ～400 kA of instantaneous current if we assume the electron beam duration is 100 fs.This high flux and its secondary radiation are widely applicable in nuclear and QED physics,industrial imaging,medical and biological studies.     

大功率电子辐照加速器扫描磁铁芯管的研制

扫描磁铁芯管的研制是大功率电子辐照加速器引出系统的关键技术之一,本文详细叙述了扫描磁铁芯管的选材、结构设计和加工工艺,并利用有限元方法对芯管壁面加强筋的形状及位置进行了优化,对芯管的焊接工艺进行了总结归纳,最终保证该芯管在大功率烟气脱硫加速器上使用时状况良好.     

Carrier-free production of Tc at an electron accelerator

We report on the results of studies of the ⁹⁵Tc isotope production conditions in a poorly investigated ⁹⁶Ru(γ,N)⁹⁵Tc reaction at a relatively inexpensive electron accelerator. Based on the analytical model it is demonstrated the possibility for estimating the effective and peak cross-sections and the isotope yield for a given reaction in a thick production target without preliminary determination of its excitation function. For this purpose we compared specific activities of two small samples that were activated under the same conditions using the reference reaction ⁶⁸Zn(γ,p)⁶⁷Cu and the one under investigation. The experiment on simultaneous photo-activation of natural zinc and ruthenium targets was performed followed by the investigation of their isotope composition. The specific activity of the radionuclide was measured and cross-sections for the ⁹⁶Ru(γ,N)^95g,mTc reactions were determined. The yields of desired isomers and admixtures in the natural ruthenium targets of different size were estimated. It is shown, in particular, that the operating conditions of the NSC KIPT accelerator KUT-30 can provide ^95gTc yields up to 120 mCi/h.     

电子束辐照制备纳米银

在水溶液中,常温常压下不加入任何催化剂,用电子加速器辐照作为一种新的方法可以成功制备出纳米银。我们利用XRD、TEM、UV、DSC来分别表征材料的结构、形貌、大小、光学特性以及材料的熔点。TEM图像证明颗粒大小为30nm,这与XRD实验通过Scherer理论公式计算的结果相一致。     

Axial ion–electron emission microscopy of IC radiation hardness

A new system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratory in Albuquerque. This system combines two entirely new concepts in accelerator physics and nuclear microscopy. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff–Pelletron to velocities of 1.9 MeV/amu. The electronic stopping power for heavy ions is near a maximum at this velocity, and their range is 20 μm in Si. These ions therefore represent the most ionizing form of radiation in nature, and are nearly ideal for performing single event effects testing of integrated circuits. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor ( a few %), which makes problematic the focussing of such ions to the submicron spots required for REM. To circumvent this problem, we have invented ion electron emission microscopy (IEEM). One can perform REM with the IEEM system without focussing or scanning the ion beam. This is because the position on the sample where each ion strikes is determined by projecting ion-induced secondary electrons at high magnification onto a single electron position sensitive detector. This position signal is then correlated with each REM event. The IEEM system is now mounted along the beam line in an axial geometry so that the ions pass right through the electron detector (which is annular), and all of the electrostatic lenses used for projection. The beam then strikes the sample at normal incidence which results in maximum ion penetration and removes a parallax problem experienced in an earlier system. Details of both the RFQ-booster and the new axial IEEM system are given together with some of the initial results of performing REM on Sandia-manufactured radiation hardened integrated circuits.     

电子束辐照制备纳米镍

在水溶液中,常温常压下不加入任何催化剂,用电子束加速器辐照作为一种新的方法可成功制备纳米镍。利用X射线衍射(XRD)、透射电子显微镜(TEM)、激光衍射粒度分布仪(LSPSDA)、紫外可见光分光光度计(UV)、样品振荡磁力计(VSM)和差热分析仪(DSC)来分别表征材料的结构、形貌、大小、粒径分布、光学特征、磁学性能以及材料的熔点。TEM图像和LSPSDA分布图证明颗粒大小为39nm,这与XRD实验通过Scherer理论公式计算的结果相一致。     

Concept of electron accelerator-driven system based on subcritical cascade reactor

A concept of accelerator-driven system consisting of electron accelerator, neutron-generating target and two-core subcritical blanket with fast and thermal neutron spectrum has been presented. Some general features of the cascade neutron multiplication in the two-core subcritical blanket are discussed. Calculation results are demonstrated for the processes of electron–photon–neutron interactions of electron beam with the target material. Neutronic and heat engineering characteristics of the facility are also described. It has been shown that with the system's subcritical level of 2% and electron beam power of 4 MW, the facility power is as high as 50 MW.     

环氧树脂电子束辐射效应研究

为了研究不同结构的环氧树脂在电子束辐射条件下的辐射化学行为及其对环氧树脂辐射固化行为与性能的影响。通过对环氧树脂电子束辐射前后的粘度变化、加热失重率以及辐射产生的小分子的对比研究发现,各种环氧树脂在电子束辐射下均有不同程度的辐射分解反应发生。其中,以缩水甘油酯型环氧树脂和含酯基的环氧树脂的分解最为严重,缩水甘油胺环氧树脂次之,缩水甘油醚环氧树脂受电子束辐射的降解影响最小。     

The influence of magnetic field on the beam quality of relativistic electron beam long-range propagation in near-Earth environment

In recent years,it has been proposed to use satellite-mounted radio-frequency(RF)accelerators to produce high-current relativistic electron beams to complete debris removal tasks.However,when simulating the long-range propagation(km-range)process of the electron beam,it is difficult to directly use the particle-in-cell method to simultaneously consider the space charge effect of beam and the influence of the geomagnetic field.Owing to these limitations,in this paper,we proposed a simplified method.The ps-range electronic micropulses emitted by the RF accelerator were transmitted and fused to form a ns-range electron beam;then,combined with the improved moving window technology,the model was constructed to simulate the long-range propagation process of the relativistic electron beam in near-Earth environment.Finally,by setting the direction of movement of the beam to be parallel,perpendicular and at an inclination of 3° to the magnetic field,we analyzed and compared the effects of the applied magnetic fields in different directions on the quality of the beam during long-range propagation.The simulation results showed that the parallel state of the beam motion and magnetic fields should be achieved as much as possible to ensure the feasibility of the space debris removal.     

电子束辐照对冷却猪肉杀菌保鲜效果的研究

利用电子束辐照技术对冷却猪肉的杀菌和保鲜效果进行了研究,为电子束辐照技术应用于肉类加工业提供应用依据。以束流能量（X1）和辐照吸收剂量（X2）为试验因子,以菌落总数（Y）为指标,通过响应面分析法（RSM）研究了电子束辐照杀菌的效果及对货架期的影响。电子束辐照对冷却猪肉杀菌效果的二次多项数学模型为：Y=3．78—0．24X1-0．13X2-0．16X1X2—0．18X1^2＋0．15X2^2（R^2=0．9755）。辐照吸收剂量与束流能量之间存在协同增效作用,试验因子的显著性顺序为：剂量〉交互作用〉束流能量。使冷却肉初始菌数下降2个对数单位的辐照参数范围为3．23-4．0kGy,2．3～3．8MeV。经电子束辐照的冷却猪肉样品在4℃条件下贮藏,货架期比对照样品延长12d左右;在7～10℃条件下保存,货架期比对照延长9d左右。研究结果表明,电子束辐照对冷却猪肉具有杀菌保鲜作用,该研究对电子束辐照技术应用于冷却猪肉的生产实践具有指导意义。     

PIC方法在RFQ加速器z-code和t-code模拟程序中的应用研究

本文介绍了二维PIC(Particle in cell)方法,这种方法常用于粒子动力学模拟中空间电荷作用的计算。并比较了以时间为自变量(t-code)和以纵向位置为自变量(z-code)的两种动力学模拟程序;针对“国家重点基础研究发展规划”洁净核能项目中的射频四极(RFQ)加速器结构参数,给出了单束加速和正、负离子束同时加速两种情况下,t-code和z-code模拟得出的传输效率。结果表明,当束团的相位宽度大或能散大时,z-code在计算空间电荷作用时会引入相对较大的误差,从而应该使用t-code来进行动力学模拟,以获得更准确的结果。     

一台300kV电子帘加速器辐照箱屏蔽物理设计

介绍一台电子能量为300keV、束流强度为60mA的电子帘加速器辐照箱的屏蔽物理设计。箱体厚度为1．5cm的铅。     

环氧树脂分子量对电子束辐射固化效果的影响

研究了分子量对于环氧树脂电子束辐射固化行为的影响规律。环氧树脂体系的辐射反应速率随分子量增加而下降,在低辐射剂量下,高分子量树脂的固化度和固化层厚度较小,提高辐射剂量,分子量的影响减弱。对于辐射固化程度较高的样品,其玻璃化温度(Tg)和贮能模量(E’)主要受固化度控制。电子束辐射固化的环氧树脂进行热处理后,样品的玻璃化温度和高温E’均有所提高,低分子量树脂的热处理效果更为明显。     

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。     

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。     

高频高压电子辐照加速器主机室辐射场研究

通过使用MCNP模拟计算和实际测量相结合的方法,对高频高压电子辐照加速器主机室辐射场的主要来源和影响其场强的因素进行了分析。结果表明:主机室的辐射场源项贡献主要来源于辐照室电子打靶后的散射辐射,影响主机室内辐射场强度的因素主要是主机室与辐照室之间管道孔的大小,以及管道孔内屏蔽材料的厚度。     

电子束在MOS结构中的能量沉积与辐照效应

根据电子输运“双群理论”计算出电子在Ｓｉ－ＳｉＯ２材料中的能量沉积。用与硅等２效的外推电离室测定了１．０ＭｅＶ和１．５ＭｅＶ的电子束在ＭＯＳ电容芯片中的吸收剂量。用Ｘ光电子谱、俄歇谱、深能级瞬态谱和Ｃ－Ｖ方法测量分析了ＭＯＳ电容Ｓｉ－ＳｉＯ２材料化学结构，界面态密度和Ｃ－Ｖ曲线在辐射前后的变化，根据理论和实验结果，从辐射剂量学的角度分析讨论了电子能量沉积，电离缺陷和辐射效应间的关系，并提出一个关于