聚合物光纤辐照特性的实验研究

分析了聚合物受辐照后发生物理化学变化的机理,实验研究了聚苯乙烯（PS）、聚碳酸脂（PC）、聚甲级丙烯酸甲脂（PMMA）三种聚合物光纤在不同辐照剂量下光传输性能的变化以及其恢复特性.在各种辐照剂量下,光透过率有不同程度的下降,经过一段时间后也有不同程度的回复,并且恢复主要发生在停止辐照后的较短时间内.在102 Gy以下,辐照造成的光损伤经过一段时间基本可以恢复,在更高剂量的辐照下(超过5*10³ Gy),辐照对光纤造成了永久损伤,经过很长时间也只能恢复一部分.实验结果表明,PS光纤的抗辐照特性最好,PC光纤优于PMMA光纤.     

射频场照射下同核体系的弛豫

根据WBR理论和同核体系的特点,构造出了一个相应的三维转动,利用Wigner旋转矩阵的特性并借助于计算机代数语言,计算出了射频场照射下同核体系完整的弛豫方程组.在此基础上,给出了射频场照射下纵向与横向弛豫时间的计算公式,并从理论上研究了射频场的照射对同核体系弛豫的影响.研究结果表明:1)射频场的照射对同核体系的弛豫有一定程度的影响.2)在射频场的照射下,同核体系的纵向弛豫时间T1小于无射频场时的T1,而横向弛豫时间T2大于无射频场时的T2.3)纵向弛豫时间T1随射频场的增强而逐渐减小,横向弛豫时间T2随射频场的增强而逐渐增大. 关键词： 核磁共振 弛豫 射频场 三维转动     

晶体塑性有限元方法研究辐照对多晶铜力学性能的影响

将辐照硬化理论与晶体塑性理论结合, 运用ABAQUS有限元分析软件模拟辐照后多晶铜的拉伸过程。分析辐照效应对材料屈服强度、硬化过程、晶体变形等力学性能的影响, 研究位错密度的演化及空间分布规律。数值模拟表明: 辐照效应提高多晶铜的屈服应力, 影响不同阶段的硬化和软化现象; 辐照剂量增大导致位错密度增殖总体变缓, 空间不均匀度增大; 晶体的塑性变形及晶体转动也受到辐照的影响, 在相同的应变条件下, 辐照剂量越大, 晶体塑性变形程度越小, 塑性变形分布不均匀度变大, 同时晶体转动程度及转动角离散度增大。     

Problems of homogeneous irradiation of Si ingots more than 200 mm in diameter under neutron doping

The problem of homogeneous irradiation of Si ingots of large diameter (i.e., comparable with the thermal neutron diffusion length in silicon—20 cm) by thermal neutrons is considered. The effect of neutron absorption on the irradiation homogeneity is discussed. It is established for some usual cases of neutron doping that the neutron distribution in the irradiation zone affects the irradiation homogeneity. The results obtained can be useful for choosing and designing the irradiation zone for neutron doping of silicon.     

Dynamical response of helium bubble motion to irradiation with high-energy self-ions in aluminum at high temperature

Brownian-type motion of helium bubbles in aluminum and its dynamical response to irradiation with 100-keV Al⁺ ions at high temperatures has been studied using in situ irradiation and transmission electron microscopy. It is found that, for most bubbles, the Brownian-type motion is retarded under irradiation, while the mobility returns when the irradiation is stopped. In contrast, under irradiation, a small number of bubbles display exceptionally rapid motion associated with the change in bubble size. These effects are discussed in terms of the dynamical interaction of helium bubbles with cascade damage formed by the high-energy self-ion irradiation.     

γ-射线辐射还原法制备金属铜掺杂MF气凝胶

采用γ射线辐射还原法,在不同总吸收剂量条件下制备了金属Cu掺杂三聚氰胺-甲醛(MF)有机气凝胶复合材料。利用X-射线衍射仪(XRD)、电感耦合等离子体吸收光谱(ICP-AES)仪和扫描电子显微镜,测试证实了辐射还原法能成功地在MF气凝胶中还原出金属Cu。扫描电子显微镜(SEM)图谱表明在100kGy和200kGy的总吸收剂量下,在MF气凝胶中还原的金属Cu粒子的粒径较小,不会形成金属团聚区,而在较高的总吸收剂量下(大于200kGy),在MF气凝胶中还原的Cu会形成金属团聚区。N2吸附测试表明,还原的金属Cu会堵塞MF气凝胶的一部分微孔和一部分介孔,从而使样品的比表面积和吸附量降低。随着总吸收剂量不断增加,经辐照后样品中金属Cu的含量也不断增加,同时还会影响还原出金属Cu的分布和形貌。     

Dosimetry problem in the case of accidental combined irradiation and its possible solution by the example of the consideration of the effect of a number of radiation factors during the Chernobyl accident

The paper is devoted to the radiation monitoring problem under conditions of accidental multifactorial irradiation during nuclear reactor accidents, including real-time monitoring. An algorithm of the corrections for the contributions to the effective equivalent dose (in addition to the main (gamma) irradiation) of the external beta irradiation and internal irradiation of incorporated iodine-131 decay is proposed.     

质子辐照下Mo/Si多层膜反射镜的微观结构状态

利用透射电子显微镜对质子辐照前后空间太阳望远镜Mo/Si多层膜的微观结构进行了表征, 并对其辐照前后反射率的变化进行了测量.研究表明, Mo/Si多层膜经质子辐照后形成了一些缺陷结构,局部区域Mo/Si的周期性遭到破坏, Mo层与Si层的宽度发生了变化,多层膜层与层之间的界面也比辐照前更为粗糙,部分层状结构由于质子辐照发生了明显的扭曲和折断等现象;此外,质子辐照导致了Mo/Si多层膜反射率的下降,这些微观缺陷的形成是光学性能降低的直接诱因. 关键词： 空间太阳望远镜 Mo/Si多层膜 微观结构 反射率     

Microwave annealing of defects in ferroelectric triglycine sulfate

The effect of microwave irradiation of ferroelectric triglycine sulfate (TGS) samples with different degrees of imperfection (determined by the annealing conditions) has been investigated. It is shown that the irradiation effect depends on both the degree of perfection of the samples and the irradiation time (dose). As for gamma irradiation, low doses of microwave radiation lead to partial annealing of defects and, therefore, should improve the parameters of TGS-based devices. High irradiation doses cause degradation of TGS properties, which is highest in perfect crystals.     

电子束辐照对GaN基LED发光性能的影响

研究了不同能量的电子束辐照对GaN基发光二极管(Light emitting diode,LED)发光性能的影响。利用实验室提供的电子束模拟空间电子辐射,对GaN基LED外延片进行1.5,3.0,4.5 MeV电子束辐照实验,并应用光致发光(Photoluminescence,PL)谱测试发光性能。结果表明:在1.5 MeV电子束辐照下,采用10 kGy剂量辐照时,LED的发光强度增加约25%;而在100 kGy剂量辐照时,LED的发光强度降低约16%。3 MeV的电子束辐照可使原来色纯度不高的LED的色纯度变好,而更高能量的辐照将会引起器件失效。     

Measurement of internal friction and shear modulus of aluminium-magnesium alloy after neutron irradiation at 78 K

The internal friction and shear modulus of polycrystalline Al + 3 at.% Mg was studied as a function of temperature after fast neutron irradiation, at liquid nitrogen temperature (78 K). The initial increase of shear modulus after irradiation is mainly due to the dislocation pinning of the irradiation induced defects. The further increase of shear modulus during annealing is caused by the bulk-effect. The recovery of shear modulus up to room temperature is similar to that of the residual electrical resistivity after a low temperature neutron irradiation. However, we may point out that in contrast to stage II, in stage III we observe a recovery of shear modulus that is distinctly more pronounced than that of electrical resistivity. The temperature dependence of internal friction, before irradiation, shows a peak at 230 K. After neutron irradiation we observe no peak in the temperature region, from 90 K to 300 K.     

Active measuring method for investigating the irradiation effect on the gain characteristics of an erbium-doped fiber amplifier in inter-satellite optical communication

An active measuring method is proposed for the first time to study the irradiation effect on the gain characteristics of an erbium-doped fiber amplifier (EDFA) for inter-satellite optical communication, which is feasible from the engineering viewpoint. The measuring method based on the irradiation model can predict the irradiation effect on the gain characteristics just by measuring the variation of the EDFA signal output power at one irradiation dose rate in the irradiation experiment. Therefore, one can avoid removing the erbium-doped fiber (EDF) from the EDFA, which is needed in the previously tested passive measuring method. These experimental measurements meet completely the requirements of the technical specifications for inter-satellite optical communication. Finally, an irradiation experiment has also been carried out to evaluate the new method by a simple test procedure.     

强脉冲X射线辐照Si-SiO2界面对C-V 和I-V特性曲线的影响

 利用强脉冲X射线对Si-SiO₂界面进行了辐照，测量了C-V曲线和I-V曲线。实验发现，经过强脉冲X射线对Si-SiO₂界面进行的辐照，使C-V曲线产生了正向漂移，这一点与低剂量率辐射结果不同；辐射后，感生I-V曲线产生畸变；特别地，从I-V曲线上还反映出强脉冲X射线辐照的总剂量效应造成电特性 参数明显退化，最后甚至失效。讨论了强脉冲X射线辐照对Si-SiO₂界面产生损伤的机理，并对实验结果进行了解释。     

Microstructure and hardening effect of pure tungsten and ZrO2 strengthened tungsten under carbon ion irradiation at 700℃

Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO₂ alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 ℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The W-1.5%ZrO₂ alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO₂ phase improves the sink strength for irradiation defects. It is confirmed that the W-1.5%ZrO₂ alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO₂ into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials.     

典型模拟电路低剂量率辐照损伤增强效应的研究与评估

采用变剂量率和变温两种辐照方法,对4款典型模拟电路的低剂量率辐照损伤特性及变化规律进行了研究与评估,分析了两种辐照方法下其辐照敏感参数的变化,比较了不同辐照方式下器件的退化程度,讨论了这两种实验室加速评估低剂量率辐照损伤方法的机理.结果显示,变剂量率辐照可以较快地预测实际低剂量率下的辐照损伤趋势,且在较低的总剂量下能够给出不太保守的估计,但其预测的总剂量受到器件退化速度的影响;变温辐照加速评估方法能够保守地估计其低剂量率下的辐照损伤,其评估范围不仅可达1000 Gy(Si),且可将评估时间缩短为12 h左右.研究结果表明,双极电路的低剂量率辐照损伤增强效应与感生的界面态密度和氢化的氧空位缺陷有关,辐照时剂量率和温度的改变会促进界面态的生长,抑制界面态的钝化作用,从而激发器件的辐照损伤潜能.     

Neutron irradiation effects on AlGaN/GaN high electron mobility transistors

AlGaN/GaN high electron mobility transistors (HEMTs) were exposed to 1 MeV neutron irradiation at a neutron fluence of 1 × 10¹⁵ cm^-2. The dc characteristics of the devices, such as the drain saturation current and the maximum transconductance, decreased after neutron irradiation. The gate leakage currents increased obviously after neutron irradiation. However, the rf characteristics, such as the cut-off frequency and the maximum frequency, were hardly affected by neutron irradiation. The AlGaN/GaN heterojunctions have been employed for the better understanding of the degradation mechanism. It is shown in the Hall measurements and capacitance-voltage tests that the mobility and concentration of two-dimensional electron gas (2DEG) decreased after neutron irradiation. There was no evidence of the full-width at half-maximum of X-ray diffraction (XRD) rocking curve changing after irradiation, so the dislocation was not influenced by neutron irradiation. It is concluded that the point defects induced in AlGaN and GaN by neutron irradiation are the dominant mechanisms responsible for performance degradations of AlGaN/GaN HEMT devices.     

HIRFL微束辐照装置偏转磁铁的安装准直

微束辐照装置是将辐照样品的束斑缩小到μm量级, 能够对辐照粒子进行准确定位和精确计数的实验平台, 是开展辐照材料学、 辐照生物学、 辐照生物医学和微加工的有力工具。 μm量级的束流对设备的准直安装也提出了极高的要求, 对于HIRFL系统微束线上的二极磁铁, 由于其所在位置的空间相当狭小, 使得设计就位时磁铁的位置及角度与地面做基准时的不同, 这给安装准直工作带来了挑战。 通过引入变化的基准坐标值的办法, 有效解决了这一难题, 使全部磁铁安装误差都控制在了要求的公差范围之内。 Microbeam irradiation facility is a experiment platform, which can reduce the beam spot on the irradiated sample to micrometer level, and can accurately locate and count the radioactive particles. It is a powerful research tool for the irradiation material science, irradiation biology, irradiation biomedicine and micro mechanical machining. The microbeam irradiation facility requires the precise work for installation and alignment. These conditions make magnet’s change for directions and positions because the location space of dipole magnets in micro beam line of HIRFL(Heavy Ion Research Facility in Lanzhou) is very small. It is a challenge for the installatior and alignment work of magnets. It was solved by transforming coordinates of benchmarks of magnets, which controlled the error of magnet setup within error tolerance range.     

PNP输入双极运算放大器在不同辐射环境下的辐射效应和退火特性

研究了PNP输入双极运算放大器LM837在1 MeV电子和⁶⁰Coγ源两种不同辐射环境中的响应特性和变化规律. 分析了不同偏置状态下其电离辐照敏感参数在辐照后三种温度 (室温, 100 ℃, 125 ℃)下随时间变化的关系, 讨论了引起电参数失效的机理. 结果表明: 1 MeV 电子辐照LM837引起的损伤主要是电离损伤, 并且在正偏情况下比⁶⁰Coγ源辐照造成的损伤大; 辐照过程中, 不同辐照源正偏条件下的偏置电流变化都比零偏时微大; 在不同的辐照源下, LM837辐照后的退火行为都与温度有较大的依赖关系, 而这种关系与辐照感生的界面态密度增长直接相关. 关键词： PNP 输入双极运算放大器 60Coγ源')" href="#">电子和⁶⁰Coγ源 偏置条件 退火     

微波辐照对无线电引信的影响与作用机理

 选择某型集成电路无线电近炸引信,从勤务处理状态和工作状态两方面,研究了无线电引信的微波辐照效应,确定了被试无线电引信的微波辐照损伤阈值范围在140~150 kW/cm²之间,误炸阈值在100 kW/cm²左右。微波辐照通过前门耦合导致无线电引信的高频振荡管和低频组件产生硬损伤,通过直接作用于起爆执行电路使处于工作状态的无线电引信出现误炸。     

Formation of defect density superlattices in binary compounds under nuclear irradiation

Manifestation of antisite defects in crystals under irradiation is studied. Calculations show that the concentration of such defects can reach high levels under typical irradiation intensities and temperatures. It is shown that buildup of antisite defects and interaction between them can result in instability of the system during irradiation with respect to spatially nonuniform perturbations. The instability should give rise to a periodic modulation of the density of antisite defects. The region of instability as a function of crystal parameters and irradiation has been obtained.