钝化层结构对氚辐伏电池转换性能的影响

在辐射伏特效应同位素电池(辐伏电池)中,器件的辐伏转化性能不仅受限于换能器件所用的半导体材料、结构或加载放射源的种类,还受换能器件表面钝化层结构的影响。为在氚化钛源加载的平面单晶硅PN结辐伏电池(氚辐伏电池)中得到最佳的钝化效果,本文设计了3种不同的钝化层结构,考察其初始输出性能和抗辐射性能,并单独研究了氚化钛源出射的X射线对单晶硅换能器件的辐射损伤。结果显示:在辐伏电池初始输出性能方面,Si/SiO2/Si3N4结构Si/B-Si glass/Si3N4结构Si/Si3N4结构;在抗氚化钛源辐射损伤方面,Si/Si3N4结构Si/B-Si glass/Si3N4结构Si/SiO2/Si3N4结构,Si/B-Si glass/Si3N4结构具有最佳的抗X射线辐射衰减性能。氚化钛源出射的X射线对辐射损伤效应起主要作用,XPS结果显示,X射线长时间辐照造成了单晶硅表面平整性的破坏。     

63Ni辐射伏特同位素电池原型的研制

利用理论研究获得的换能单元参数制备了单晶硅基换能单元,确定了⁶³Ni的加载工艺和原型电池的封装材料配方与技术,通过加速热老化和温度交变考核了原型电池的性能。结果表明：所制备的⁶³Ni辐射伏特效应微型同位素原型电池的短路电流I_sc、开路电压V_oc、最大输出功率P_max和衰变能-电能转换效率η分别为5.97 nA、88.0 mV、0.255 nW和0.561%;原理样机稳定输出超过220 d。     

应用于等离子体排灰气处理的甲烷水汽重整反应的热力学分析

Tokamak装置中的等离子体反应一段时间后,需对产生的排灰气进行净化处理,以回收其中的氘氚。目前拟采用甲烷水汽重整反应将化合态的氘氚转化为单质并回收。本文运用Gibbs自由能最小化方法,对应用于等离子体排灰气处理的水汽重整反应进行热力学分析,考查反应温度、原料比例、反应压力、O₂、CO₂、H₂、CO等因素对反应平衡的影响,确定了适宜的反应条件,即反应温度范围650～700 ℃,压力1×105 Pa,水碳比1.5～2.0。此外,原料气中O₂或CO₂的存在有利于减少积碳的生成量,并获得较高的氢同位素平衡转化率;H₂的存在对重整反应的热力学平衡无明显影响;CO的存在会使积碳量增加,对反应产生不利影响,在进入重整反应器前应将其去除。     

D+注入Li4SiO4的表面化学状态及其热解吸行为

锂陶瓷氚增殖剂的氢同位素行为是聚变堆固态产氚包层关心的重要课题。本文将3 keV D⁺注入Li₄SiO₄,采用X射线光电子能谱在线分析注氘前后材料表面的化学状态,同时采用热解吸谱（TDS）实验技术,研究注氘后Li₄SiO₄中氢同位素的热解吸行为。实验结果表明：D⁺注入会改变Li₄SiO₄表面的化学环境,产生多种辐照缺陷和化学键合状态;氘滞留量和热解行为受注氘时样品的温度影响较大,可在一定程度上预测产氚包层中氚的滞留行为。     

吸附温度低于273 K的Pd/k柱TCAP全回流实验研究

为满足实验室规模的氢同位素分离需求,对少量氚（小于3.7×10¹³ Bq）的高效氢同位素分离方法进行了研究。采用TCAP全回流工艺,将钯/硅藻土（Pd/k）填充色谱柱（长2 m,外径6 mm）吸附H-D混合气体（D丰度为50%）的温度控制在273 K以下,经多次加热 冷却循环后,从分离柱前、后两端加热各提取15%样品气,利用低温色谱法对样品气进行氢同位素丰度分析,对色谱柱的分离性能进行评价。研究结果发现,原料气进入填充柱后（全回流之前）尾端提取气的氘丰度约为98.5%,经5个全回流循环（循环总时间为1.25 h）后,尾端提取气的氘丰度达99.9%。经15个全回流循环后,前端提取气的氘丰度由50%（原料气氘丰度）降至13.6%。通过实验数据对柱中氘分布进行了理论模拟,发现进样速率过快可能是导致前端提取气氘丰度过高的主要原因,柱中氘丰度最低点可能出现在色谱柱的中部。     

氚基同位素电池设计优化及其电学性能的提升

采用蒙特卡罗方法开展了氚基同位素电池在辐致伏特效应和辐致光伏效应两种不同能量转换模式下的性能研究。探讨了换能材料的几何物理参数对电池电学输出性能的影响，设计制备了单层和叠层两类氚基同位素电池，测试分析了增大氚源强度、采用叠层构型两种方式对电池电学输出的提升效果。模拟结果表明：Si、SiC、GaAs光伏组件均可用于辐致伏特效应氚基同位素电池换能，且存在各自最佳厚度参数，使得电池电学输出性能达到最优，分别为3.8μm、2.2μm、1.7μm；对于辐致光伏效应氚基同位素电池，可通过调整ZnS∶Cu荧光层的厚度，使出射的荧光辐照度达到最大，进而优化电池电学输出性能。结果提示，增大氚源强度、采用叠层构型均可实现氚基同位素电池最大输出功率等电学参数的有效提升，其中并联叠层的最大输出功率可达到106.138 nW，相比于单层构型增幅超过64%。     

基于两级钯膜反应器的氚水处理技术

为了处理高浓氚水,搭建了一台氢-水同位素交换串联水汽变换的两级钯膜反应器装置,可以实现级联处理工艺。以天然水代替氚水为源项,以D₂代替H₂开展了除氢实验,最高获得了207.4的除氢因子,验证了两级钯膜反应器用于处理氚水的可行性。通常情况下,水汽变换反应的除氢因子大于氢-水同位素交换反应。其中,氢-水同位素交换中D₂/H₂O体积流量比越大,该反应除氢因子越大;氢-水同位素交换中原料侧压力越大,该反应除氢因子越大;原料水流量越大,两个反应的除氢因子均会下降。由于一级膜反应器采用氢-水同位素交换可将氚水浓度降低1个量级以上,因而可以尽量避免二级膜反应器中CO与高浓氚接触,抑制含氚有机物的生成。由此可见,两级钯膜反应器有望成为一种高效的氚水处理装置。     

氚在RAFM钢中的渗透

采用气相渗透方法，开展了国产低活化铁素体/马氏体钢（RAFM钢?）之一的CLAM钢的氚渗透实验，研究了影响渗透的关键因素，建立了可靠的实验方法。在573~823?K温度范围内，得出氚的渗透率F_T为2.57×10-8exp(-38639/RT)，氚溶解度S_T为2.2×10-1exp(-38639/RT)，扩散系数D_T?为1.17×10-7exp(-22011/RT)。另外，氘氚混合渗透时存在明显的正同位素效应，在实验温度范围内，推导得出的氘氚渗透分离系数α_DT为1.42，氕氚渗透分离系数α_HT为3.76。      

GaN器件辐伏同位素电池的电输出性能研究

利用⁶³Ni和3H源分别辐照两种可作为辐伏电池换能单元的GaN基PiN结型器件,其输出短路电流（I_sc）和开路电压（V_oc）分别为：对于⁶³Ni源,I_sc＝5.4 nA,V_oc＝771 mV;对于3H源,I_sc＝10.8 nA,V_oc＝839 mV。其开路电压显著优于单晶硅基器件辐伏电池的输出结果,但与理论值有一定的差距。可能是GaN材料生长过程中产生的缺陷、电极欧姆接触不良以及器件结构等原因,导致短路电流和开路电压未能达到期望值。这些是提升GaN换能单元辐伏电池的电输出性能应解决的重要技术问题。     

氦中痕量H2、D2组分的高精度气相色谱分析

为满足聚变堆氘氚燃料循环工艺气体中痕量氢同位素组分的特殊检测分析要求,需建立快速、高精度的在线分析方法。针对氦中痕量H₂、D₂组分,本工作以高纯氦为载气,在液氮温度下,使用自制改性Al₂O₃毛细管柱进行分离,放电氦离子化检测器进行检测。结果显示,氢氘组分的检测限不高于1×10^-8,保留时间不高于180 s,氢氘组分色谱峰峰面积响应值的相对标准偏差不大于1.0%,分离度大于1.0。本方法具有分析灵敏、快速的优点,为聚变堆包层在氘氚燃料注入系统和氢同位素分离系统中微量氚的安全分析与精确计量提供了一种有效的测量技术。     

Enhancement of pumping performance of electrochemical hydrogen pump by modified electrode

Electrochemical hydrogen pump with ceramic proton conductor membrane has been proposed to apply for a blanket tritium recovery system (BTR) of a fusion reactor. The advantage of this system is that it can apply to the system of low hydrogen pressure, because the driving force of hydrogen permeation is the electric potential difference. Perovskite-type ceramic such as SrCe_0.95Yb_0.05O₃₋ (SCO) is one of the candidates of membrane. To apply hydrogen pump to BTR, the enhancement of the hydrogen transportation capability is necessary. Modification of electrode is one of the methods to enhance the hydrogen transportation capability. In this work, the electrodes of platinum (Pt) and palladium (Pd) were attached to the SCO sample by the sputtering method (sputtering electrode), and its electric conductivity and proton conductivity were measured. Then, they were compared with that of the usual Pt paste electrode. Hydrogen transportation capability was enhanced when the sputtering electrode was applied. Especially, in case of the Pd sputtering electrode, the current density which was about 4 or 5 times larger than the usual Pt paste electrode was observed at 0.1% of H₂ concentration.     

Tritium diffusivity in crystal grain of Li2TiO3 and tritium release behavior under several purge gas conditions

It has been reported by the present authors that behavior of tritium release from solid breeder grain is consisted of diffusion in grain, tritium transfer at surface layer and surface reactions on grain surface such as adsorption or isotope exchange reactions. Tritium release curves estimated using the tritium release model gave good agreement with observed tritium release curves from Li₄SiO₄, Li₂ZrO₃ or LiAlO₂.

Tritium release behavior from Li₂TiO₃ under humid purge gas, dry purge gas and dry purge gas with hydrogen conditions is discussed in this study, tritium release curves using the release model that we proposed previously give a good agreements with experimental tritium release curves. Tritium effective diffusivity in the crystal grain of Li₂TiO₃ is also estimated in this study using a curve-fitting method applied to the release curves obtained under the humid purge gas condition. It is discussed that change of color of Li₂TiO₃ surface under hydrogen purge gas condition is observed and this phenomenon might affect tritium release behavior from Li₂TiO₃.     

LaNi_(4.25)Al_(0.75)吸氕、氘、氚热力学同位素效应

采用自制的全金属氢化物吸放氢实验装置,恒温等容条件下测定LaNi_(4.25)Al_(0.75)材料吸氕、氘、氚单质气体的压力-组成等温线(P-C-T曲线),并根据Van’t Hoff(范特霍夫)方程得到LaNi_(4.25)Al_(0.75)吸氕、氘、氚形成氢化物相的热力学参数焓变ΔH分别为:-44.5、-45.0、-47.1kJ·mol-1,熵变ΔS分别为:-118.0、-121.8、-127.5J·mol~(-1)·K~(-1)。结果表明:LaNi_(4.25)Al_(0.75)材料吸收氕、氘、氚单质气体,在温度较低时,同位素效应不明显;温度高于100℃时,热力学同位素效应显著。相同温度、吸气容量条件下,吸气平衡压力从低到高依次是氕、氘和氚,其反应焓变和熵变从小到大依次是氚、氘和氕。结果表明,LaNiAl合金吸氢的热力学同位素效应依赖于温度的变化。     

Deuterated liquid scintillator (NE230) as a fast neutron detectorfor cold-fusion and other research

Deuterated scintillators (NE230) can provide, without time-of-flight, usable neutron energy spectra for neutrons E _n⩾1 MeV. The authors have assembled and calibrated several of these detectors and used them in experiments searching for d+d fusion-neutron emission (E_n, 2.5 MeV) in Pd+D ₂O electrolysis and Ti+D₂ adsorption at LN temperatures. The detectors yielded direct fusion-neutron spectra and set limits in the Pd+D and Ti+D experiments of <7×10^-24 fusion n/s/dd pair and <3×10^-24 fusion n/s/dd pair respectively. In addition, these detectors have been used for in-beam accelerator experiments requiring coincidence between fast neutrons and scattered ions     

Effect of Cr2O3 nanosheet insertion on the deuterium permeation behavior of a Cr-Zr-O coating

In this study, a Cr₂O₃ nanosheet (Cr₂O₃ NS) inserted Cr-Zr-O coating was developed as a hydrogen isotope permeation barrier. The Cr₂O₃ NSs, fabricated by rapid heat treatment, were amorphous with a thickness of only several nanometers. These Cr₂O₃ NSs were then incorporated into a Cr-Zr-O multi-metal oxide composite coating via a dip-coating method to form a coating. The effect of the Cr₂O₃ NS concentration on the morphology, microstructure and deuterium permeation resistance of the coating was studied. With the addition of 1.0 g l−1 Cr₂O₃ NSs, compared with the Cr-Zr-O coating without NSs, the permeation reduction factor of the resultant coating was enhanced from 249 °C to 575 °C at 500 °C. The coating, with a thickness of nearly 193 nm, achieved a comparable deuterium resistance that was above two orders of magnitude higher than the steel substrate. The results show that ceramic NSs can serve as effective fillers for enhancing the coating performance when functioning as a hydrogen isotope barrier.     

铒二氢化物的氘、氚热力学同位素效应

在真空系统中对金属铒的氘活化特性进行了测试,测定了铒与氘、氚反应生成二氢化物及其可逆反应的压强-组成-温度（PCT）曲线。结果显示,铒的氘、氚化物α+β相平台区较宽且十分平坦,其二氘化物和二氚化物分解反应均未见明显滞后效应。基于PCT曲线获得了H/Er原子比在0.6～1.6区间的标准焓（ΔH°）和标准熵（ΔS°）,其数值均随H/Er比的增大而减小,相同原子比下氚化物的ΔH°和ΔS°较氘化物的小,具有轻微的同位素效应。其中,ErD₁的ΔH°和ΔS°分别为（-199.7±7.3）kJ/mol和（-143.4±7.2） J/(mol•K),ErT₁的ΔH°和ΔS°分别为（-209.3±3.3） kJ/mol和（-152.9±3.2）J/(mol•K)。