3D hydrogen profiling by elastic recoil detection analysis in transmission geometry

An analytical procedure and a simulation-optimization algorithm are described for hydrogen determination based on elastic recoil detection induced by low-energy ⁴He ions ( 3 MeV) using transmission geometry. Hydrogen concentration depth profiles can be derived from the experimental recoil spectra for a depth range of up to 6 μm with a resolution better than 40 nm at the surface. The method is applied to thin polyimide films irradiated by high-energy heavy ions. The 3D hydrogen distribution is determined with a ⁴He⁺ mubeam. A high-hydrogen-concentration zone below the surface is shown. The hydrogen distribution is seen to evolve during the ⁴He⁺ irradiation.     

强碱性阴离子交换树脂用于90YCl3溶液金属杂质的纯化

从⁹⁰Sr/⁹⁰Y放射性衰变平衡体系中分离获得的90Y溶液具有无载体、金属杂质含量高等特点,需要进一步纯化才能应用于⁹⁰Y放射性药物的制备。本工作研究了AE4强碱性阴离子交换树脂在盐酸溶液中对Y³⁺、Fe³⁺、Al³⁺、Zn²⁺、Mg²⁺的吸附性能。结果表明：AE4树脂在盐酸溶液中不吸附Al³⁺、Zn²⁺、Mg²⁺;在3 mol/L以上的盐酸溶液中对Fe³⁺吸附性能较好;在7 mol/L以上的盐酸溶液中对Y³⁺的吸附性能较好。含有Y³⁺、Al³⁺、Zn²⁺、Mg²⁺等元素的混合溶液在3 mol/L HCl溶液通过AE4树脂柱后,Fe³⁺基本被全部吸附在树脂柱上;吸附余液调节盐酸浓度至7 mol/L,通过另一根AE4树脂柱,Y³⁺基本被吸附在树脂柱上。最后用0.01 mol/L HCl洗脱吸附在树脂柱上的Y³⁺,得到纯化后的YCl₃溶液。稳定核素和90Y示踪的研究结果表明,采用AE4树脂纯化⁹⁰YCl₃溶液的工艺可行,AE4树脂可用于90YCl3溶液中Fe、Al、Zn、Mg等主要杂质金属元素的去除。     

Design of Q-band FMCW reflectometry for electron density profile measurement on the Joint TEXT tokamak

The Q-band(33-50 GHz) fast sweep frequency modulated continuous wave(FMCW)reflectometry has been recently developed for electron density profile measurement on the Joint TEXT tokamak.It operates in ordinary mode(O-mode) with a 20 μs sweeping period,covering the density range from 1 × 10~(19) m~(-3) to 3 × 10~(19) m~(-3).On the bench test,a Yttrium Iron Garnet(YIG) filter is used for the dynamic calibration of the voltage controlled oscillator(VCO) to obtain a linear frequency sweep.Besides,the use of a power combiner helps to improve the sideband suppression level of the single side-band modulator(SSBM).The reconstructed density profiles are presented,which demonstrate the capability of the reflectometry.     

含杂质的卢瑟福散射的蒙特卡罗模拟

采用蒙特卡罗方法数值研究了杂质对α粒子卢瑟福散射的影响。杂质原子根据靶材的纯度以给定的概率随机替换靶材原晶格的原子。研究结果表明,考虑杂质后,出射粒子随散射角分布的曲线中形成了新的峰,峰的位置随杂质元素原子序数的增加向大角度方向移动;杂质的原子序数越低、含量越高,对卢瑟福散射出射粒子角分布的影响越明显;同时,入射粒子能量越低,杂质产生的峰对分布曲线的影响越明显。此外,对典型的C6+、N7+等重离子束的卢瑟福散射的模拟计算结果表明,重离子束对杂质有更好的分辨率。     

LiCl-KCl-LaCl_(3)熔盐体系中La^(3+)的反应动力学机理北大核心CSCD

在LiCl-KCl共晶盐中,研究了在不同温度下La^(3+)的反应动力学机理。首先,在723~873 K范围内,利用循环伏安法(CV)测得La^(3+)的扩散系数D为3.06×10^(-5)~6.08×10^(-5)cm^(2)/s,并根据Arrhenius方程计算了La^(3+)在电解质中的扩散活化能E_(D)=34.51 kJ/mol。随后,利用电化学阻抗谱技术(EIS)研究了La^(3+)在电极上的动力学参数并测得交换电流密度i_(0)为0.48~1.39 A/cm^(2)、反应速率常数k_(0)=2.04×10^(-4)~5.90×10^(-4)cm/s及反应活化能E_(a)=35.04 kJ/mol。通过Nyquist图和拟合的等效电路图研究La^(3+)在W电极上的反应动力学机理,发现在LiCl-KCl共晶盐中La^(3+)的电化学反应速率不仅受扩散控制还受电荷转移控制,且与温度成正相关。     

RBS studies of the lattice damage caused by 1 Me V Si implantation into Al0.3Ga0.7As/GaAs superlattices at elevated temperature

The lattice damage accumulation in GaAs and Al_0.3Ga_0.7As/GaAs superlattices by 1 MeV Si⁺irradiation at room temperature and 350°C has been studied. For irradiations at 350°C, at lower doses the samples were almost defect-free after irradiation, while a large density of accumulated defects was induced at a higher dose. The critical dose above which the damage accumulation is more efficient is estimated to be 2 × 10¹⁵ + Si/cm² for GaAs, and is 5 × 10¹⁵ Si/cm² for Al_0.8Ga_0.7As/GaAs superlattice for implantation with 1.0 MeV Si ions at 350°C. The damage accumulation rate for 1 MeV Si ion implantation in Al_0.3Ga_0.7As/GaAs superlattice is less than that in GaAs.     

Study on Radial Position of Impurity Ions in Core and Edge Plasma of LHD Using Space-Resolved EUV Spectrometer

Radial profiles of impurity ions of carbon, neon and iron were measured for high-temperature plasmas in large helical device (LHD) using a space-resolved extreme ultraviolet (EUV) spectrometer in the wavelength range of 60 to 400?. The radial positions of the impurity ions obtained are compared with the local ionization energies, Ei of these impurity ions and the electron temperatures TeZ there. The impurity ions with 0.3?Ei?1.0 keV are always located in outer region of plasma, i.e., 0.7?ρ?1.0, and those with Ei?0.3keV are located in the ergodic layer, i.e., 1.0?ρ?1.1, with a sharp peak edge., where ρ is the normalized radial position. It is newly found that TeZ is approximately equal to Ei for the impurity ions with Ei?0.3keV, whereas roughly half the value of Ei for the impurity ions with 0.3?Ei?1.0keV. It is known that TeZ is considerably lower than Ei in the plasma edge and approaches to Ei in the plasma core. Therefore, this result seems to originate from the difference in the transverse transport between the plasma edge at ρ?1.0 and the ergodic layer at ρ?1.0. The transverse transport is studied with an impurity transport simulation code. The result revealed that the difference appearing in the impurity radial positions can be qualitatively explained by the different values of diffusion coefficient, e.g., D=0.2 and 1.0m2/s, which can be taken as a typical index of the transverse transport.     

Low energy nitrogen ion doping into GaAs using combined ion-beam and molecular-beam epitaxy method

Low energy nitrogen (N) ions were irradiated during the epitaxial growth of GaAs using combined ion beam and molecular beam epitaxy (CIBMBE) method as a function of N⁺ ion acceleration energy (E_a) and N⁺ ion beam current density (I_N). E_a was varied from 70 to 170 eV I_N from 900 pA/cm² to 75 nA/cm². GaAs growth rate was fixed to 1 μm/h. In 2 K photoluminescence (PL) spectra of the samples with I_N = 3 nA/cm² and E_a = 70–100 eV, two sharp emissions at 1.508 eV (X₁) and 1.495 eV (X₂), which have been attributed to the emissions of excitons bound to isolated N atoms, and another one at 1.443 eV (X₅) were observed. These results show that nitrogen (N) atom in GaAs becomes optically active as an isoelectronic impurity at least in as-grown condition. For N⁺ ion-irradiated samples with rather high I_N, e.g., with I_N = 75 nA/cm² and E_a = 100 eV, a broad emission together with multiple sharp ones were observed after furnace annealing at 750°C which were ascribed to emissions of excitons bound to nitrogen-nitrogen (N---N) pairs.     

Depth profiling study on the migration of tritium in titanium induced by deuterium-ion bombardment

A thin titanium layer with uniformly absorbed tritium (T/Ti ˜1.0) was bombarded by 390 keV D₃⁺ ions (130 keV per deuteron). Bombardment was performed at low (111 K) and room temperatures up to fluences of 5.9 × 10¹⁸ D/cm² and 3.0 × 10¹⁸ D/cm², respectively. Depth profiles of tritium up to a depth of 0.8 mg/cm² (˜1.8 μm) were measured and the change of the profile with fluence was investigated by means of the T(d, )n nuclear reaction. At both of the temperatures, a dip was formed on the depth profile of tritium at the depth around the projected range, indicating that the deuteron bombardment induced the migration of tritium against the concentration gradient. At the low temperature, the dip showed a gradual growth with fluence and saturation of the growth at the higher fluences, which could not be described by the existing model for isotope mixing. The spectrum of protons from the D(d, p)T reaction obtained in the same measurement suggested that the release of deuterium suddenly started at the final stage of the present bombardment. The dip formed at room temperature was larger than that at the low temperature. The migration of tritium induced by the bombardment is discussed on the basis of the experimental results obtained.     

镁固溶对钙钛锆石陶瓷固化体的影响北大核心CSCD

以CaTiO_(3)、ZrO_(2)、TiO_(2)和MgO为原料,经固相烧结法在1350℃下制备镁固溶钙钛锆石陶瓷固化体(Ca_(1-x)Zr_(1+x)Ti_(2-x)Mg_(x)O_(7),0≤x(固溶度)≤0.20),并研究Mg^(2+)固溶度对固化体物相组成、微观形貌和晶体结构的影响。X射线衍射结果表明:Ca_(1-x)Zr_(1+x)Ti_(2-x)Mg_(x)O_(7)结构中的Ti位可容纳固溶度x=0.05~0.15的Mg^(2+);并通过选区电子衍射实验进一步验证,固化体的主要晶体结构为单斜相钙钛锆石(2M,空间群C2/c)。当固溶度x=0.05~0.15时,钙钛锆石产物的相对质量分数高于97%,仅有微量的钙钛矿杂质相生成;随着Mg^(2+)固溶度的进一步增加(x=0.20时),Mg^(2+)浓度超过固溶度极限,使杂质相含量大幅增加。同时,扫描电子显微镜观察结果表明,固化体抛光面结构致密;在Mg^(2+)固溶度x≤0.15时,阳离子浓度符合所设计的化学计量比。     

考虑聚并及热泳的微米级气溶胶粒子沉积数值模拟研究

本文基于C++编写的程序对0.5~10 μm气溶胶粒子沉积进行了数值模拟,研究了聚并和热泳对沉积的影响及其耦合作用。结果表明,气溶胶粒子数量浓度小于10¹²m^-3时,聚并可忽略;气溶胶粒子数量浓度为10¹⁴ m^-3时,聚并不可忽略。考虑聚并后,气溶胶粒子的沉积速度显著增加,如在温度梯度为3 000 K/m时,10 μm气溶胶粒子的沉积速度较不考虑聚并时增大了37.2%。不考虑聚并、温度梯度为3 000 K/m时,由于热泳作用,0.5 μm气溶胶粒子沉积速度增大到无温度梯度的5.96倍,考虑聚并后,减小为4.41倍（数量浓度为10¹⁴ m^-3）。聚并和热泳会相互影响,但总体上聚并和热泳均会增强气溶胶粒子的沉积,从而加快气溶胶粒子的损失。     

Static and dynamic deformations stimulated by ion implantation

The laser interferometric technique has been applied for the investigation of the quasi-static and dynamic components of the elastic deformation of crystalline silicon wafers during implantation of Ar⁺ and He⁺ ions. The absolute values of the integral stress and the amplitude of deformation vibrations are measured as a functions of implanted ions dose, energy and current density and compared with the dose dependencies of the surface acoustic waves (SAW) velocity in the implanted layer. The correlation between integral stress, amplitude of vibrations and SAW velocity variations is shown.     

Temperature-dependent dose rate effects in CMOS/SOS devices

The measured photocurrent output by the 3392-μm p-channel and 1992-μm n-channel transistors in the output buffer of the Harris 05131A Octal Latch manufactured in the TSOS4 1.25-μm CMOS/SOS process are used to extract the field and temperature-dependent conductivity of the sapphire substrate. The bulk conductivity was found to vary from 2.15×10^-15 Ω^-1/cm/rad(Si)/s at -55°C to 4.16×10^-15 Ω^-1/cm/rad(Si)/s at +125°C. Parasitic transistor action contributed significant photocurrents with the gain of the n-channel increasing from 1.3±0.3 at -55°C to 5.7±3.3 at +125°C. The gain of the p-channel followed the same temperature variation, with 1.6±0.5 at -55°C to 7.0±2.0 at +125°C. The temperature-dependence of both the substrate and parasitic transistor action appeared due to an Arrenhius variation of the carrier lifetime or mobility controlled by a trap 0.05 eV above the quasi-Fermi level     

电沉积法制备镍-63放射源工艺研究

微型核电池用镍-63放射源要求放射源表面发射率高、镀层薄、衬底小,以小体积、高比活度、低镍浓度的镍-63溶液作为电沉积液,建立一种直流恒流电沉积制备镍-63放射源的方法。采用该方法,衬底为紫铜材质、Ni²⁺浓度为1 g/L、电沉积液pH为3.5～4.5、氨基磺酸浓度为0.1 g/L条件下电沉积1 h,电沉积率可达95.8%。制备的镍-63放射源源片镀层紧密、光亮,厚度0.3~1.6 μm,其表面发射率最高可达2.40×10⁷ s^-1·(2πSr)^-1,活度最高可达1.89×10⁹ Bq,满足微型核电池的应用需求。同时,通过对剩余电沉积液进行回收、组分调节,实现了电沉积液的重复利用,减少了镍-63原料的浪费。     

Estimation of plasma density perturbation from dusty plasma injection by laser irradiation on tungsten target in DiPS

To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator, radial profiles of plasma density(ne) and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips. Dusty plasma with dusts(a generation rate of 3 μg s~(-1) and a size of 1–10 μm)was produced via interactions between a high-power laser beam and a full tungsten target. As ne increases, the scale of the effects of dusty plasma injection on magnetized plasmas was decreased. Also, the duration of transient fluctuation was reduced. For numerical estimation of plasma density perturbation due to dusty plasma injection, the result was ~10% at a core region of the magnetized plasma with n_e of(2–5)×10~(11) cm~(-3) at steady state condition.     

Secondary ion emission from beryllium surfaces by Ar and /or (Ar+D2) mixed ion bombardments

With respect to the impurity emission and erosion of a Be first wall, a secondary ion mass spectrometric investigation was carried out along with surface characterization with X-ray photoelectron spectroscopy. It was found that Be is emitted as distinct types of chemical forms from the surface owing to sputtering with Ar⁺ and an (Ar⁺+ D⁺₂) mixture: (i) Be and Be-cluster, (ii) oxide and hydroxide, and (iii) hydride and/or deuteride.     

CS-30回旋加速器制备111In

在四川大学CS-30回旋加速器上通过核反应^NatCd（p,xn）¹¹¹In进行了制备放射性核素¹¹¹In的研究。实验选用高纯度的天然镉作为靶材料,并采用电沉积法制备靶件,研究了辐照靶件的溶解以及放射化学分离方法。结果表明,采用26 MeV的质子轰击天然靶件,并采用CL-P204树脂将In与Cu²⁺、Cd²⁺、Zn²⁺等杂质进行分离,可以得到产额（EOB 48 h,即轰击结束48 h后）约为25~28 MBq/（μA•h）的¹¹¹In,其放射性核素纯度大于99%,Cu²⁺和Cd²⁺等化学杂质总质量浓度小于8.0 mg/L。     

PdY合金管束的氢渗透性能

PdY合金膜因其具有良好的透氢性能与机械性能,有望应用于聚变堆氢同位素纯化工艺。基于PdY合金膜的服役参数及氚安全要求,有必要研究在低氢压下PdY合金膜的氢同位素渗透特性,为后续设计氢同位素纯化组件提供数据支撑。本工作基于直管外压式PdY扩散器,研究了低氢压(<50 kPa)、工作温度为350～450℃条件下,厚度为80μm的PdY合金薄膜管的氢渗透速率与膜两侧压力、工作温度的关系。结果表明,低氢压下,PdY合金膜的氢渗透规律符合■,且压力指数n等于0.9,渗透速率控制机制主要表现为表面过程控速;提高工作温度使得合金膜的渗透通量增大,且温度对扩散过程的影响更大,使渗透过程更加趋于表面控速。此外,计算了该工作温度范围下的渗透系数,并通过阿伦尼乌斯公式推导求得渗透活化能约为24.54 kJ/mol,渗透常数Φ₀为5.86×10^-6 mol/(m·s·kPa^0.9)。低氢压下,该厚度膜的渗透系数可由5.86×10^-6e~(-24.54/(RT)) mol/(m·s·kPa^0.9...     

Investigation on the characteristics of an atmospheric-pressure microplasma plume confined inside a long capillary tube

An atmospheric-pressure microplasma plume of diameter 10 μm is generated inside a long tube. The length of the microplasma plume reaches as much as 2 cm. First, with the assistance of an air dielectric barrier discharge (DBD), the ignition voltage of the microplasma decreases from 40 kV to 23.6 kV. Second, although the current density reaches as high as (1.2−7.6)×10⁴ A cm ⁻² , comparable to the current density in transient spark discharge, the microplasma plume is non- thermal. Third, it is interesting to observe that the amplitude of the discharge current in a positive cycle of applied voltage is much lower than that in a negative cycle of applied voltage. Fourth, the electron density measured by the Stark broadening of Ar spectral line 696.5nm reaches as high as 3×10¹⁶ cm⁻³ , which yields a conductivity of the microplasma column of around 48 S m⁻¹ . In addition, the propagation velocity of the microplasma plume, obtained from light signals at different axial positions, ranges from 1×10⁵ m s ⁻¹ to 5×10 ⁵ m s⁻¹ . A detailed analysis reveals that the surface charges deposited on the inner wall exert significant influence on the discharge behavior of the microplasma.