Ion acoustic solitary waves in an adiabatic dusty plasma:Roles of superthermal electrons,ion loss and ionization

We investigate propagation of dust ion acoustic solitary wave(DIASW)in a multicomponent dusty plasma with adiabatic ions,superthermal electrons,and stationary dust.The reductive perturbation method is employed to derive the damped Korteweg-de Vries(DKdV)equation which describes DIASW.The result reveals that the adiabaticity of ions significantly modifies the basic features of the DIASW.The ionization effect makes the solitary wave grow,while collisions reduce the growth rate and even lead to the damping.With the increases in ionization cross sectionΔσ/σ_(0),ion-to-electron density ratioδ_(ie)and superthermal electrons parameterκ,the effect of ionization on DIASW enhances.

Ionization process and distinctive characteristic of atmospheric pressure cold plasma jet driven resonantly by microwave pulses

In the present study,a coaxial transmission line resonator is constructed,which is always capable of generating cold microwave plasma jet plumes in ambient air in spite of using argon,nitrogen,or even air,respectively.Although the different kinds of working gas induce the different discharge performance,their ionization processes all indicate that the ionization enhancement has taken place twice in each pulsed periods,and the electron densities measured by the method of microwave Rayleigh scattering are higher than the amplitude order of 10^(18)m^(-3).The tail region of plasma jets all contain a large number of active particles,like NO,O,emitted photons,etc,but without O_(3).The formation mechanism and the distinctive characteristics are attributed to the resonance excitation of the locally enhanced electric fields,the ionization wave propulsion,and the temporal and spatial distribution of different particles in the pulsed microwave plasma jets.The parameters of plasma jet could be modulated by adjusting microwave power,modulation pulse parameters(modulation frequency and duty ratio),gas type and its flow rate,according to the requirements of application scenarios.

Nonadiabatic Effect on the Rescattering Trajectories of Electrons in Strong Laser Field Ionization Process

The important features of the rescattering trajectories in strong field ionization process such as the cutoff of the return energy at 3.17Up and that of the final energy at 10Up are obtained, based on the adiabatic approximation in which the initial momentum of the electron is assumed to be zero. We theoretically study the nonadiabatic effect by assuming a nonzero initial momentum on the rescattering trajectories based on the semiclassical simpleman model. We show that the nonzero initial momentum will modify both the maximal return energy at collision and the final energy after backward scattering, but in different ways for odd and even number of return trajectories. The energies are increased for even number of returns but are decreased for odd number of returns when the nonzero （positive or negative） initial momentum is applied.

Laser Induced Photoelectron Impact Ionization In Multiphoton Ionization Process

Multiply charged ions of Ar and NO were observed in MPI experiment Of NO/Ar with TOF-MS. A delayable pulsed acceleration field wn applied tO investigate the effect of the photoelectrons on the formation of the multiply charged ions. The multiply charged ions were suggested to be produced by photoelectron impact ionization, in the region bentween the extractor grid and the repeller plate, step by step, from neutral species and lower charged ions. The 50-60ns of FWHM of the ion peaks implies that the pulse width of the photoelectrons should be shorter considering the broadening effect during the ionization process.

Computational simulation of ionization processes in single-bubble and multi-bubble sonoluminescence

The most recent spectroscopic studies of moving-single bubble sonoluminescence(MSBSL)and multi-bubble sonoluminescence(MBSL)have revealed that hydrated electrons(e^(-)_(aq))are generated in MSBSL but absent in MBSL.To explore the mechanism of this phenomenon,we numerically simulate the ionization processes in single-and multi-bubble sonoluminescence in aqueous solution of terbium chloride(TbCl_(3)).The results show that the maximum degree of ionization of single-bubble sonoluminescence(SBSL)is approximately 10000 times greater than that of MBSL under certain special physical parameters.The hydrated electrons(e^(-)_(aq))formed in SBSL are far more than those in MBSL provided these electrons are ejected from a bubble into a liquid.Therefore,the quenching of e^(-)_(aq)to SBSL spectrum is stronger than that of the MBSL spectrum.This may be the reason that the trivalent terbium[Tb(Ⅲ)]ion line intensities from SBSL in the TbCl_(3) aqueous solutions with the acceptor of e^(-)_(aq)are stronger than those of TbCl_(3) aqueous solutions without the acceptor of e^(-)_(aq).Whereas the Tb(Ⅲ)ion line intensities from MBSL are not variational,which is significant for exploring the mechanism behind the cavitation and sonoluminescence.

Role of XUV Photons in Atomic High-Order Above-Threshold Ionization Processes in IR+XUV Two-Color Laser Fields

We investigate the above-threshold ionization of an atom in a combined infrared （IR） and extreme ultraviolet （XUV） two-color laser field and focus on the role of XUV field in the high-order above-threshold ionization （HATI） process. It is demonstrated that, in stark contrast to previous studies, the XUV laser may play a significant role in atomic HATI process, and in particular, the XUV laser can accelerate the ionized electron in a quantized way during the collision between the electron and its parent ion. This process cannot be explained by the elassical three-step model Our results indicate that the previously well-established concept that HATI is an elastic recollision process is broken down.

An investigation of ionizing radiation damage in different SiGe processes

Different SiGe processes and device designs are the critical influences of ionizing radiation damage. Based on the different ionizing radiation damage in SiGe HBTs fabricated by Huajie and an IBM SiGe process, quantitatively numerical simulation of ionizing radiation damage was carried out to explicate the distribution of radiation-induced charges buildup in KT9041 and IBM SiGe HBTs. The sensitive areas of the EB-spacer and isolation oxide of KT9041 are much larger than those of the IBM SiGe HBT, and the distribution of charge buildup in KT9041 is several orders of magnitude greater than that of the IBM SiGe HBT. The result suggests that the simulations are consistent with the experiment, and indicates that the geometry of the EB-spacer, the area of the Si/SiO2 interface and the isolation structure could be contributing to the different ionizing radiation damage.

PRECURSOR IONIZATION AHEAD OF STRONG SHOCK WAVES IN ARGON

The mechanism of precursor ionization ahead of strong shock waves has been studied in a low density shock tube. The experimental results are illustrated with Arrhenius plots with kink points dividing them into two parts with apparent activation energy ratio 1:2, namely with the values 7.7 eV and 15.3 eV, and varying with first and third power of the density respectively. A model is proposed to interpret the facts where the process taking place in the precursor region is a two step photo ionization accompanied with the drift flow effect of the gas relative to the shock wave or the ionization recombination effect according to whether the shock speed and initial density are low enough. The product of the A-A collision excitation cross section coefficient S* multiplied by the radiation cross section Q of Argon S×Q=1×10^(-36)(cm^4eV^(-1)) and the three body recombination coefficient of Argon at room temperature k_(ra)=1×10^(-24)(cm^(-6)s^(-1)).

Reactivity of N-Methylidenemalonates of 3-Arylaminoindoles and p-Dimethylamino-N-Phenylaniline in the Course of Their Analysis by Electrospray Ionization Mass Spectrometry

The behavior of N-methylidenemalonates of 3-arylaminoindoles and p-dimetylamino-N-phenylanyline (M = ANa) was studied during their analysis with ESI mass spectrometer operated in negative (NI) and positive (PI) ion modes. Anions [A] and both [M + H]+ and [M + Na]+ were recorded under conditions of the NI-ESI and PI-ESI, respectively. The fragmentation processes of [A] and [M + H]+ were found that probably occurred as “insource collusion induced dissociation”. The main paths for [A] proved to be elimination of CO2 and breakage of the N-methylidenemalonate bond. A route [A]- - CO2 - ROH (R = Me or Et) was less expressed and occurred for the indolyl-containing compounds with the NH bond only. Experiments employing heavy water demonstrated the isotope exchange to occur involving the hydrogen atom of this bond. This and other facts evidenced that the last fragmentation included abstraction of just this atom. Quantum-chemical calculations allowed picking out a structure for the product ion from the possible ones. The calculations also indicated that the protonation of M occurred at the anionic oxygen atom of the malonate moiety. The fragmentation of [M + H]+ ions included elimination of two water molecules that was supported by their MS2 spectra. A common feature of the NI- and PI-ESI mass spectra was the presence of oligomeric ions, up to tetramers and trimers for the NI- and PI-ESI ones, respectively. The oligomers were formed by interaction of the corresponding ions with neutral molecules. When ions contained extra hydrogen atoms, they were introduced by hydrolysis.

Experimental study on the detonation process of a pulse detonation engine with ionized seeds

An experimental platform of a pulse detonation engine(PDE) was established to study the effect of different K_2 CO_3 ionized seed mass contents on the detonation process.The pressure and ion concentration were detected in the detonation process of the PDE with different contents of ionized seeds.The initiation process of the PDE at different ignition frequencies was studied.The results show that the gas conductivity in the detonation process increased by adding ionized seeds to the PDE tube,and the conductivity increased with the increase in ionized seed mass content.With the increase in ionized seed mass content,the range of the conductivity decreased.The PDE was successfully ignited and formed a stable detonation wave at ignition frequencies of 5 Hz and 10 Hz,and the peak pressure of the stable detonation with the ignition frequency of 5 Hz was 17% higher than that with an ignition frequency of 10 Hz.The detonation wave intensity was weake ned and dege nerated to a shock wave that propagated in the tube without the fuel filled at the ignition frequency of 20 Hz.

Ionization of two-electron atom(xenon)studied by Bohmian mechanics theory

The ionization dynamics of two-electron atom in an intense laser field is studied by the Bohmian mechanics(BM)theory, and the xenon atomic potential function is used as a model. The single ionization process and double ionization process are calculated by the BM theory and their results are in good agreement with those calculated by numerically solving the time-dependent Schrodinger equation. The analyses of the types, trajectories, and forces of Bohmian particles(BPs)undergoing the single and double ionizations indicate that the re-collision process accounts for a considerable proportion in the singly ionized cases. Furthermore, the analysis of the work done by the external force acting on the BPs shows that the quantum force plays an important role in the re-collision process. This work is helpful in understanding the ionization of two-electron atom in an intense laser field.

Nonlinear Ionization of Molecules by Intense Transform-Limited Gaussian Laser Pulses

We present in this paper an investigation of the nonlinear process of above-threshold ionization. The process arises when an atomic or molecular system, exposed to an intense laser pulse, continues to absorb more photons than that needed for the ionization to occur. We trigger this nonlinear process in a simple molecular system by exposing it to an intense transform-limited Gaussian laser pulse of 267-nm wavelength which is the third harmonic of an 800-nm wavelength Tisapphire laser. We explore the characteristics of the process by analyzing the kinetic-energy spectra of the electrons ejected from the molecular system under different laser peak intensities.

集成电路和功率器件抗辐射工艺加固技术研究综述

随着我国空间装备的高速发展,尤其是深空探测器,微电子器件抗辐射性能得到广泛关注。抗辐射工艺加固是实现器件抗辐射性能提升的重要途径之一。本文围绕空间总剂量效应和单粒子效应,对近年来集成电路和功率器件辐射效应机理和工艺加固技术的研究进展进行了介绍和总结,为抗辐射工艺加固技术的发展与应用提供了有益参考。

本征基区尺寸对双极器件总电离剂量辐射效应的影响

基于标准0.18μm BCD工艺,对双极器件总电离剂量(TID)辐射效应进行了研究,提出了一种提高双极器件抗总电离剂量辐射能力的方法。理论分析表明,在标准0.18μm BCD工艺中,双极器件总电离剂量辐射的敏感区域位于浅沟槽隔离结构下方、基极接触区和发射极边缘之间的本征基区。对不同本征基区尺寸的双极器件进行了总电离剂量辐射实验,研究了本征基区尺寸对双极器件电流增益随总电离剂量退化的影响。实验结果表明,在相同总电离剂量下,双极器件本征基区尺寸越小,增益衰减比例越小,辐射敏感性越低。将10 V纵向npn(VNPN)器件的本征基区尺寸由1.4μm减小至0.6μm,可将150 krad(Si)总电离剂量辐射后的归一化电流增益由0.6132增大到0.7081。因此,减小本征基区尺寸是一种有效的双极器件总电离剂量辐射加固技术。

半夏炮制过程中毒性凝集素蛋白的基质辅助激光解吸电离飞行时间质谱分析

基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)受灵敏度和重复性的影响,对完整蛋白的定量分析存在困难。本研究采用纤维素纳米晶体(CNC)辅助MALDI-TOF MS,结合内标法定量分析半夏炮制过程中半夏凝集素(PTL),通过优化CNC辅助样本制备的时长和比例,以麦胚凝集素(TVL)为内标,直接分析不同炮制程度半夏各炮制品及其浸泡上清液中PTL含量。结果表明,CNC辅助MALDI样本制备有效提升了MALDI-TOF MS定量分析的线性和重复性。随着炮制时间的延长,姜半夏、清半夏和法半夏炮制品的PTL含量逐渐下降,浸泡上清液中PTL含量逐渐上升。其中,由于pH值的改变,法半夏炮制品浸泡上清液中PTL含量呈先上升后下降的趋势。此外,将该方法应用于不同饮片生产企业的多批次半夏炮制品饮片中,均未检出PTL。该方法操作简便,可有效分析半夏炮制过程中PTL含量的变化,为研究半夏炮制过程对PTL的影响提供了参考。

Determination of Di-n-Butyl Phosphate in Organic Streams of FBTR Mixed Carbide Fuel Reprocessing Solution by Gas Chromatographic Technique

The present work describes the amount of Di-n- butyl phosphate (DBP) produced when PUREX solvent (30%tri-n-butyl phosphate (TBP) mixed with 70% hydrocarbon diluent) is exposed to intensive radiolytic and chemical at- tack during the separation of uranium and plutonium from fission products of FBTR mixed carbide fuel reprocessing solution. DBP is the major degradation product of Tri-n-butyl phosphate (TBP). Amount of DBP formed in the lean organic streams of different fuel burn-up FBTR carbide fuel reprocessing solutions were analyzed by Gas Chromatographic technique. The method is based on the preparation of diazo methane and conversion of non-volatile Di-n-butyl phosphate in to volatile and stable derivatives by the action of diazomethane and then determined by Gas Chromatography (GC). A calibration graph was made for DBP over a concentration in the range from 200 to 1800 ppm with correlation coefficient of 0.99587 and RSD 1.2%. The degraded 30% TBP-NPH solvent loaded with heavy metal ions like uranium was analyzed after repeated use and results are compared with standard ion chromatographic technique. A column comparison study to select of proper gas chromatographic column for the separation of DBP from other components in a single aliquot of injection is also examined.

高气压环境等离子弧行为与工艺研究

等离子弧切割技术因其高效稳定的工艺优势被广泛应用于工业领域.文中以空气等离子弧为研究对象,通过COMSOL Multiphysics软件建立了喷嘴结构的二维轴对称有限元数学模型,并对电弧磁流体模型进行了优化.基于磁流体动力学和电弧等离子体理论,选用等离子平衡放电多物理场接口,并确立了空气等离子电弧模型的控制方程和边界条件,实现对电弧模型的编译求解.仿真结果表明,在引弧电流一致的条件下,随着环境压力的增加,电弧在温度分布和速度分布上均呈现收缩的态势.基于3 MPa高压焊接试验舱,搭建了高压环境等离子弧切割实验系统,通过对气路和非高频引弧电路的优化设计,实现了环境压力为0.1~0.7 MPa的稳定起弧.并基于此开展了高压梯度下的等离子弧切割实验,并结合切割质量指标研究了环境压力对等离子弧电离行为的影响.

超快复合脉冲烧蚀硅表面的偏振依赖性研究(特邀)

以晶面<100>的硅片为研究对象,使用重复频率1 kHz的超快复合双脉冲作为激发工具,通过研究双脉冲之间的偏振夹角、延迟时间和脉冲数对周期性结构面积的影响,探究引起周期性结构演化的非线性电离动力学。实验结果表明,在激光能量密度为0.23 J/cm2、脉冲组合为100个的复合脉冲辐照条件下,正交偏振诱导的结构面积最小,相比于其他入射形式下诱导的最大面积减小率约为45%,这是因为局域场的反复调制抑制了周期性结构边缘烧蚀阈值的降低。在正交偏振时,随着两束脉冲之间延迟时间的改变,通过观察诱导结构面积变化可以分析从电子电离到物质喷发的连续过程。该复合脉冲调控技术可为研究超快激光诱导半导体表面周期性结构的偏振依赖性与电子电离效率提供参考,进一步的改进有望实现超衍射极限结构的快速诱导。

电镀法制备裂变电离室电极铀膜

裂变电离室电极镀铀(235 U)的均匀性、镀膜厚度和结合力是影响中子探测器灵敏度等性能关键所在,以无水乙醇为电镀液,铂丝为阳极,通过考察阴极镀件(铝管)处理工艺、pH值、电流密度、电镀时间和镀液中U(Ⅵ)初始浓度对电镀效率及镀膜的影响,进而确定了电镀铀的最佳工艺参数。研究结果表明,当电流密度为6.50 mA/cm^(2)、电镀时间为30 min、pH=2.6、极间距为12 mm、镀液中U(Ⅵ)初始质量浓度为1.96 mg/mL时,电镀效率约达92.4%,镀膜厚度可达2.26 mg/cm^(2)。采用X射线光电子能谱(XPS)和扫描电镜(SEM-EDS)等对镀层进行了表征。XPS表明U以六价态的UO_(2)+2聚合物和四价态的二氧化铀(UO_(2))形式存在,且纯度较高。SEM显示镀层表面平整、致密。划痕法测试结果表明,镀层结合力一般。

Influence of laser intensity on the double-resonance multiphoton ionization process of NO molecule

The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.