在等离子体中镁离子谱线MgⅡλ4481?的宽度和位移

本工作测量了MgIIλ4481?(3²D—4²F)在电子数密度为7×10¹⁶—3.1×10¹⁷电子数/cm³范围内的谱线轮廓和位移。采用振荡型电容放电作为光谱光源。在光源中引入水汽,由测量H_β谱线宽度来定电子数密度。观测结果指出,H_β的实验轮廓和Griem-Kolb-Shen的计算结果符合颇好。实验发现MgIIλ4481?谱线向紫方位移,并正比于微观电场的平方;由此定出一个经验上的二级斯塔克效应常数C₄=5.0×10^-14cm⁴/sec。该谱线的轮廓宽度和标准微观电场之间也有平方正比的关系。发现在本实验条件范围内,宽度和位移的比值γ/△保持为常数,其值为γ/△=10.4±0.6。由于谱项4²D的二级斯塔克效应的干扰而产生上能级4²F位移的理论计算虽能说明谱线位移和微观电场间的平方正比关系,但数值偏小于实验结果,指出还有电子贡献的部分。把光谱线的宽度和Lindholm理论公式及Griem等的近似公式作了比较;简单的估计指出,实验结果和后者符合较好。     

Cl/HN3/I2全气相化学激光体系的化学动力学模拟计算

 对Cl/HN₃/I₂产生NCl(a)/I激光的过程进行了化学动力学计算，主要考察了Cl,HN₃和I₂的初始粒子数密度及其配比对小信号增益系数的影响。结果发现,当温度为400K, 初始Cl粒子数密度为1×10¹⁵，1×10¹⁶和1×10¹⁷cm^-3时,小信号增益系数分别达到1.6×10^-4,1.1×10^-3和1.1×10^-2cm^-1，获得最佳小信号增益系数的HN₃和I₂的初始粒子数密度分别为初始Cl粒子数密度的1～2倍和2%～4%。同时，对Cl，HN₃和I₂配比对小信号增益系数和增益持续时间的影响进行了讨论。     

空气放电非平衡等离子体的模拟计算

 基于空气放电非平衡等离子体动力学,对空气放电进行了数值计算,分析了放电后等离子体中的主要粒子（N₂(v6),N₂(A3),O₂(a1),O和O₃）数密度随起始温度、电子数密度和约化场强的变化趋势。计算结果表明,随着初始温度的升高,空气放电产生的粒子数密度增加。温度为300 K时,放电产生的O原子数密度最大值约为4.90×⁷ cm^-3,而当温度升高到400 K和500 K时,O原子数密度的最大值则相应地增加到5.2×10¹⁰ cm^-3和5.51×10¹⁰ cm^-3。约化场强的影响与温度类似,其中氮气的振动激发态N₂(v6)数密度随约化场强的变化幅度不明显。电子数密度增加,粒子数密度大幅增加,氮分子的激发态N₂(A3)粒子数密度与电子数密度保持严格的线性关系。     

甲基环己烷在9∽15.5 eV能量区的真空紫外光电离研究

利用具有同步辐射源的反射式飞行时间质谱仪，研究甲基环己烷的真空紫外光电离和光解离. 观测到母体离子C₇H₁₄⁺和碎片离子C₇H₁₃⁺，C₆H₁₁⁺，C₆H₁₀⁺，C₅H₁₀⁺，C₅H₉⁺，C₄H₈⁺，C₄H₇⁺和C₃H₅⁺的光电离效率曲线. 测定甲基环己烷的电离能为9.80±0.03 eV，通过光电离效率曲线确定其碎片离子的出现势. 在B3LYP/6-31G(d)水平上对过渡态、中间体和产物离子的优化结构进行表征，并使用G3B3方法计算其能量. 提出主要碎片离子的形成通道. 分子内氢迁移和碳开环是甲基环己烷裂解途径中最重要的过程.     

环戊酮光电离解离的实验和理论研究

本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程. 在9.0∽15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线. 通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03 eV,并确认碎片离子为：C₅H₇O⁺,C₄H₅O⁺,C₄H₈⁺,C₃H₃O⁺,C₄H₆⁺,C₂H₄O⁺,C₃H₆⁺,C₃H₅⁺,C₃H₄⁺,C₃H₃⁺,C₂H₅⁺, C₂H₄⁺. 利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C₅H₈O⁺的解离机制. 通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径.     

Orion KL超水微波激射辐射的“宁静相”物理特征

利用紫金山天文台青海观测站的13.7m的射电望远镜,观测OrionKL分子云的水微波激射辐射发现这个区的微波激射活动处于”宁静”状态,峰值流量为3×10⁴Jy,大约比爆发相微波激射辐射低两个数量级宁静水微波激射处于完全饱和的辐射过程,微波激射活动区的亮温度为3×10¹³K,氢分子数密度为8×10¹⁴m^-3,微波激射辐射两能级之间的布居反转粒子数密度为5×10⁵(H₂O)m相似文献   

酪胺和多巴胺VUV光电离/解离的实验和理论研究

利用同步辐射真空紫外光电离质谱和理论计算对中性酪胺和多巴胺分子的光诱导解离过程进行研究．在较低光子能量下,通过近阈光电离仅得到母体离子信号．当增加光子能量到11.7 eV甚至更高时,从酪胺和多巴胺分别得到四个清晰可辨的碎片离子信号．另外通过测量母体离子的光电离效率曲线,酪胺和多巴胺分子的电离能分别为7.98和7.67 eV(实验误差为±0.05 eV)．结合理论计算建立这两个分子的详细碎裂路径,包括相似的胺乙基消除路径．其中碎片C₇H₈O₂^+·(m/z=124)和C₇H₈O^+·(m/z=108)的生成认为来自McLafferty重排,该过程经历分子内的γ氢迁移诱导的β开裂反应． 另外,C7-C8键直接开裂可以生成CH₂NH₂⁺(m/z=30)碎片离子,并且该过程和McLafferty重排为主要的裂解路径.     

奇异粒子的性质及其产生和衰变

用一架30厘米×30厘米×10厘米磁场为6200高斯的云室,在海拔3185米的云南落雪高山实验室拍摄了30000对照片,获得105个V⁰,而可以进行分类的有43个。其中有26个θ₁⁰,16个Λ⁰和一个θ₂⁰。本文对θ₁⁰,Λ⁰和一个θ₂⁰进行了研究,其结果如下:1)Q值,Q_(Λ⁰)=(36.2±2.5)Mev,Q_(θ1⁰)=(233±11)Mev;2)平均寿命,τ_(Λ⁰)=(3.19_-0.92^+2.42)×10^-10秒,τ_(θ1⁰)=(1.14_-0.27^+0.49)×10^-10秒;3)动量分布与以前的工作没有显著差别;4)N(Λ⁰)/N(θ₁⁰)=0.51±0.22(权衡数);5)Λ⁰和θ₁⁰在质心系的衰变角分布没有明显的不对称性;6)一个θ₂⁰在静止坐标系寿命为～10^-9秒,衰变类型可能为θ₂⁰→π^-+π⁺+π⁰或者θ₂⁰→π^±+μ^?+ν。     

钛离子辐照对MgB2超导薄膜的载流能力和磁通钉扎能力的影响

利用混合物理化学气相沉积法(hybrid physical-chemical vapor deposition, HPCVD)可以制备出高性能的MgB₂超导薄膜, 再对薄膜进行钛(Ti)离子辐照处理.经过辐照处理后的样品被掺入了Ti元素, 与未处理的干净MgB₂样品相比,其超导转变温度没有出现大幅度的下降, 而在外加磁场下的临界电流密度得到了明显的提高,同时样品的上临界磁场也得到了提高. 在温度5 K, 外加垂直磁场为4 T的情况下, Ti离子辐照剂量为1× 10¹³/cm²的样品的临界电流密度达到了1.72× 10⁵ A/cm², 比干净的MgB₂要高出许多,而其超导转变温度仍能维持在39.9 K的较高水平.     

异亮氨酸的真空紫外光电离和光离解

利用同步辐射光电离质谱结合理论计算, 研究了异亮氨酸的真空紫外光诱导电离解离．在光子能量为13 eV的质谱中探测到了m/z=86、75、74、69、57、46、45、44、41、30、28、18的碎片离子．对于异亮氨酸的主要碎片离子为：C₅H₁₂N⁺ (m/z=86)、C₂H₅NO₄⁺ (m/z=75)、C₅H₉⁺ (m/z=69)、C₄H₉⁺(m/z=57)和CH₄N⁺(m/z=30)．由光电离效率曲线得到出现势分别为：8.84±0.07、9.25±0.06、10.20±0.12、9.25±0.10、11.05±0.07 eV．结合量化理论计算(B3LYP/6-31++G(d,p)),详细给出了它们可能的生成路径．这些解离通道包括简单的键断裂反应和涉及中间体、过渡态的反应,实验值和理论计算的离子出现能或势垒一致．     

Determination of the Electron Density in an Argon Laser Plasma by Spectroscopy of the Hydrogen Hα and Hβ Lines

From measurements of the H_α and H_β spectral line profiles in a plasma, a method is developed which allows to separate the contributions of Doppler and Stark broadening. This method is superior to the deconvolution of Voigt profiles, in particular, when the lines are of low intensity. The electron density in the plasma can be calculated from the Stark broadening. An example is the low pressure (p ≈ 1 hPa) arc discharge of argon ion lasers which is characteristised by electron densities of approximately 10¹⁴ cm^?3 at heavy particle temperatures of about 10⁴ K. These plasma parameters lead to a broadening of the Balmer H_α and H_β spectral lines of hydrogen, which has a low concentration within the discharge area. The spectral lines are broadened due to the electron density dependent Stark effect and the temperature responsive Doppler effect. The results are consistent with predictions of the argon ion laser modelling.     

Measurement of atomic hydrogen density in non-thermal H<Subscript>2</Subscript> plasmas via threshold ionisation-molecular beam mass spectrometry

Determinations of radical density are essential to investigate the physical-chemical processes in plasmas and setup the related theoretical models. This paper presents the experimental measurement of atomic hydrogen near grounded electrode in dielectric barrier discharge medium-pressure hydrogen plasma via threshold ionisation-molecular beam mass spectrometry. After investigating the possible influences from parent molecules in excited states, background component and space-charge, evolution of atomic hydrogen density as functions of discharge parameters are investigated utilising the signal of H₂ molecule beam as the reference. At fixed gas pressure of 6.0 torr and a discharge voltage of 24 kV, atomic hydrogen density increases monotonously from 1.1×10¹⁴ to 2.0×10¹⁵ cm^-3 as the discharge frequency increases from 9 to 26 kHz. Similarly the rising discharge voltage also lead to enhancement of atomic hydrogen density.     

Absolute density measurement of hydrogen atom in inductively coupled Ar/H2 plasmas using vacuum ultraviolet absorption spectroscopy

The absolute density measurement of atomic species such as hydrogen is crucial for plasma processing because of their strong chemical reactivity. In this work, to measure the hydrogen atom density in Ar/H₂ inductively coupled plasmas (ICP), the self-absorption-applied vacuum ultraviolet absorption spectroscopy (VUVAS) is studied with a micro-hollow cathode H₂/He discharge lamp (MHCL) emitting VUV light (Lyman alpha line; L_α 121.56 nm). The absolute density of hydrogen atoms in the ICP is investigated for various powers (50 W–850 W) in the low pressure region (30 mTorr–50 mTorr). The hydrogen density in remote plasma region is shown to vary from 2.1 × 10¹¹ cm⁻³ to 1.25 × 10¹² cm⁻³ with respect to plasma power.     

SiH4激光等离子体内H谱线的线型研究

本工作利用光学多道分析仪(OMA Ⅲ)测量了脉冲TEA CO₂激光诱发的SiH₄等离子体内H Balmer系的H_α,H_σ和H_γ线的线型。结果表明,三条谱线的FWHM(半值全宽度)随跃迁上能级的主量子数的增加而增加,即△λ_1/2(H_α)<△λ_1/2(H_β)<△λ_1/2(H_γ)。通过对等离子体内各类加宽机制的讨论,得出等离子体内谱线的主要加宽机制为Stark加宽。由H_α线的实验线型与Stark加宽理论线型的拟合,得到等离子体的两个重要参量,平均电子密度N≈10¹⁷cm^-3,电子温度T≈40 000K。由H_β线的时间分辨测量得到等离子体的电子密度随时间的演变曲线。 关键词：     

Elektronenverluste in einem abklingenden Wasserstoffplasma

The time dependence of the electron density in the afterglow period of an electrodeless discharge in hydrogen was measured by means of 4- and 8-mm microwave interferometry. An exponential decay was observed in the late afterglow permitting the evaluation of a time constant in the density range from 10¹²–10¹⁰ electrons per cm³. The decay time of the plasma was influenced by the discharge conditions. Electron losses could be explained by ambipolar diffusion and attachment to impurities. Two diffusion coefficients were found correlated to the discharge duration. The mobility value H₀=10.1±1.0 cm²/V · sec calculated from the diffusion coefficient found for short discharge pulses agrees with Saporoschenkos mobility value μ₀=10.2 cm²/V · sec for the H ₃ ⁺ -ion. A second mobility value μ₀=14.8±1.2cm²/V · sec found for longer discharge pulses might refer to the H⁺-ion.     

Chemisorption of H2 on W(100): Absolute sticking probability,coverage, and electron stimulated desorption

Measurements of both the absolute sticking probability near normal incidence and the coverage of H₂ adsorbed on W(100) at ~ 300K have been made using a precision gas dosing system; a known fraction of the molecules entering the vacuum chamber struck the sample crystal before reaching a mass spectrometer detector. The initial sticking probability S₀ for H₂/W(100) is 0.51 ± 0.03; the hydrogen coverage extrapolated to S = 0 is 2.0 × 10¹⁵ atoms cm^?2. The initial sticking probability S₀ for D₂/W(100) is 0.57 ± 0.03; the isotope effect for sticking probability is smaller than previously reported. Electron stimulated desorption (ESD) studies reveal that the low coverage β₂ hydrogen state on W(100) yields H⁺ ions upon bombardment by 100 eV electrons; the ion desorption cross section is ~ 1.8 × 10^?23 cm². The H⁺ ion cross section at saturation hydrogen coverage when the β₁ state is fully populated is ? 10^?25 cm². An isotope effect in electron stimulated desorption of H⁺ and D⁺ has been found. The H⁺ ion yield is ? 100 × greater than the D⁺ ion yield, in agreement with theory.     

Formation of bubbles and blisters in hydrogen ion implanted polycrystalline tungsten

ABSTRACT

Tungsten (W) has been regarded as one of the most promising plasma facing materials (PFMs) in fusion reactors. The formation of bubbles and blisters during hydrogen (H) irradiation will affect the properties of W. The dependence of implantation conditions, such as fluence and energy, is therefore of great interest. In this work, polycrystalline tungsten samples were separated into two groups for study. The thick samples were implanted by 18?keV H₃⁺ ions to fluences of 1?×?10¹⁸, 1?×?10¹⁹ and 1?×?10²⁰ H⁺/cm², respectively. Another thick sample was also implanted by 80?keV H₂⁺ ions to a fluence of 2?×?10¹⁷ H⁺/cm² for comparison. Moreover, the thin samples were implanted by 18?keV H₃⁺ ions to fluences of 9.38?×?10¹⁶, 1.88?×?10¹⁷ and 5.63?×?10¹⁷ H⁺/cm², respectively. Focused ion beam (FIB) combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for micro-structure analysis, while time-of-flight ion mass spectrometry (ToF-SIMS) was used to characterize the H depth profile. It is indicated that bubbles and blisters could form successively with increasing H⁺ fluence. H bubbles are formed at a fluence of ～5.63?×?10¹⁷ H⁺/cm², and H blisters are formed at ～1?×?10¹⁹ H⁺/cm² for 18?keV H₃⁺ implantation. On the other hand, 80?keV H₂⁺ ions can create more trapping sites in a shallow projected range, and thus enhancing the blisters formation with a relatively lower fluence of 2?×?10^17?H⁺/cm². The crack-like microstructures beneath the blisters are also observed and prefer to form on the deep side of the implanted range.     

Measurements of emission coefficient for continuum radiation from shock-heated krypton plasmas

Using a shock tube, the ξ factor of krypton has been determined at λ = 456.1 nm by observations of the continuum radiation and simultaneous interferometric measurements of the electron number density. For the electron-density range used (1×10¹⁶cm^-3?n_e?4×10¹⁶cm^-3), we obtain an increase in the ξ factor for decreasing electron densities. These results are compared with theoretical and other experimental data.     

Spectroscopic study of plasma during electrolytic oxidation of magnesium- and aluminium-alloy

We present the results of an optical emission spectroscopy study of Plasma during Electrolytic Oxidation (PEO) of magnesium- and aluminum-alloy. Plasma electron number density N_e diagnostics is performed either from the H_β line shape or from the width or shift of non-hydrogenic ion lines of aluminum and magnesium. The line profile analysis of the H_β suggests presence of two PEO processes characterized by relatively low electron number densities N_e≈1.2×10¹⁵ cm^?3 and N_e≈2.3×10¹⁶  cm^?3. Apart from these two low N_e processes, there is the third one related to the ejection of evaporated anode material through micro-discharge channels. This process is characterized by larger electron density N_e=(1.2–1.6)10¹⁷ cm^?3, which is detected from the shape and shift of aluminum and magnesium singly charged ion lines. Two low N_e values detected from the H_β and large N_e measured from the widths and shift of ion lines suggest presence of three types of discharges during PEO with aluminum- and magnesium-alloy anode. On the basis of present and earlier results one can conclude that low N_e processes do not depend upon anode material or electrolyte composition.The electron temperature of 4000 K and 33,000 K are determined from relative intensities of Mg I and O II lines, respectively. The attention is drawn to the possibility of N_e application for T_e evaluation using Saha equation what is of importance for PEO metal plasma characterization. During the course of this study, difficulties in the analysis of spectral line shapes are encountered and the ways to overcome some of the obstacles are demonstrated.     

An experimental investigation of partial LTE for lower excited levels of Ar(I) in a wall-confined,argon arc plasma

This paper contains experimental results on partial LTE in the lower excited levels of Ar(I). The experiments were performed in a well-confined argon arc source. The population densities were obtained from self-absorption measurements of the lines. Plasma parameters were determined spectroscopically; measurements included the electron density (from the H_β line width) and the electron temperature (from the Boltzmann plot for higher excited levels of Ar(I)). The results show that the levels 1s₅ to 1s₅ are in Saha-Boltzmann equilibrium for electron densities above 3 × 10¹⁶ cm^-3.