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。     

高空核爆炸下大气的X射线电离及演化过程数值模拟

利用数值模拟程序模拟了不同高度核爆炸下大气的X射线电离及演化过程.结果表明: X射线电离产生的电子数密度在射线到达后约100 ns时刻达到峰值, 峰值数密度随着到裸核区距离的增加而减小;电子具有较长的寿命, 电子寿命随着到裸核区距离的增加而增大; X射线电离空气产生正离子O⁺, O₂⁺, N₂⁺,爆高为120 km情况下 O⁺的峰值数密度与O₂⁺的相近,能维持约1 s. X射线对空气的电离影响范围在数十千米以内,在距裸核区较近的区域, 爆高为80 km时产生的电子峰值数密度比爆高为120 km时的电子峰值数密度高, 在距裸核区较远的区域则相反.     

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。     

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   

N2O+离子A2Σ+电子态高振动能级的转动结构分析

利用一束波长为36055nm的激光，通过(3+1)共振多光子电离方法制备纯净的且处于X²Π_1/2，3/2(000)态的N₂O⁺离子，用另一束激光激发所制备的离子到第一电子激发态A²Σ⁺的不同振动能级，然后解离，通过检测解离碎片NO⁺强度随光解光波长的变化，得到了转动分辨的N₂     

轻核中的U(90)动力学对称性

在IBM4中,当存在s、d、g玻色子时,体系的对称性群为U(90).本文研究了子群链:U₉₀ U₁₅(sdg)×U₆(ST) SU₁₅(sdg)×U₆(ST) SU₅(sdg)× O₆(ST) SO₅(dg)×O₃(S)×O₃(T) O₃(dg)×O₃(S)×O₃(T) O₃(J)×O₃(T)给出了约化规则和典型能谱,并在轻核中找到了具有这种动力学对称性的能谱的例子,偶偶核³⁴S与奇奇核 ³⁴Cl在一个多重态中.     

板条射频放电产生单重态氧实验研究

 通过考察各种放电状态及气流条件下发生器内外物种的自发辐射谱,发现光谱峰值强度与对应物种浓度成正比。分析了主要的等离子体动力学过程,了解了单重态氧及其它物种的浓度变化规律。考察了α放电和γ放电两种不同的放电方式。发现在α放电状态下,体系中有较少氧原子等淬灭性粒子,更有利于O₂(¹Δ)产生。加入He,有效地降低了气体体系的离子化阈能和约化场强,约化场强最小时,产生的O₂(¹Δ)浓度最大,相较于纯氧放电,O₂(¹Δ)浓度提高一倍以上。考察了腔外各物种浓度的变化,O₂(¹Δ)离开放电腔后浓度稳定,沿距离减少较慢,有益于出光。优化了本系统的放电极间距,极间距太大或太小,都不利于单重态氧的产生。     

利用喇曼光谱测量氧碘激光器氧发生器的O2（a1Δ）产率

 利用自发喇曼成像技术实时监测氧碘激光器O₂(¹Δ)发生器流场组分，得到了发生器气流中O₂(¹Δ)和 O₂(X³Σ)以及N₂的自发喇曼散射光谱，由此得到了不同条件下的O₂(¹Δ)产率，测量误差不超过8%。     

BeCl分子电子激发态的多参考组态相互作用计算

运用含Davidson修正的多参考组态相互作用方法,在aug-cc-pVTZ基组水平上,对BeCl分子基态和相同多重度的几个低电子激发态进行了势能扫描计算.通过群论原理确定各电子态对称性及离解极限.将其中基态(X²Σ⁺)和第一激发态(A²Π})对应的势能曲线拟合到Murrell-Sorbie解析势能函数形式,得到基态(X²Σ⁺)的离解能及主要光谱常数(括号中为文献[6]提供的实验值)为D_e=3.74eV,R_e=0.18173nm(0.17970),w_e=857.4cm¹(847.2),w_ex_e=5.03cm^-1(5.14),B_e=0.7103cm^-1(0.7285),α_e=0.0059cm^-1(0.0069),第一激发态(A²Π)的D_e=3.02eV,R_e=0.18369nm(0.18211),w_e=832.7cm^-1(822.1),w_ex_e=5.93cm^-1(5.24),B_e=0.6953cm^-1(0.7094),α_e=0.0065cm^-1(0.0068),计算结果与实验值符合得较好.另外,通过Level程序求解双原子径向核运动的Schrödinger方程得到J=0时BeCl分子这两个电子态的全部振动能级.     

电子通量对ZnO/K2SiO3热控涂层光学性能的影响

 研究了电子通量对ZnO/K₂SiO₃热控涂层光学性能的影响。分别采用通量为5×10¹¹/cm²·s，8×10¹¹/cm²·s，1×10¹²/cm²·s 和5×10¹²/cm²·s的电子对试样进行辐照。电子辐照下涂层的光学性能发生了退化，并且发现了退化涂层在空气中的“漂白”现象。分析了ZnO/K₂SiO₃热控涂层光学性能的退化机制，同时讨论了电子通量对太阳光谱吸收系数的影响。实验结果发现，在5×10¹¹～1×10¹²/cm²·s的电子通量范围内，电子通量对ZnO/K₂SiO³热控涂层光学性能的影响相同。因此在这个电子通量范围内，采用加速地面试验来模拟空间的电子辐照效应是有效的。     

约化场强对氮-氧混合气放电等离子体演化特性的影响

采用零维等离子体动力学模型,计算了不同约化场强条件下N₂/O₂放电等离子体的演化特性.结果表明,平均电子能量与约化场强有着近似的线性关系,在约化场强为100 Td时,平均电子能量约为2.6 eV、最大电子能量达35 eV;约化场强是影响电子能量函数分布的主要因素.气体放电过程结束后,振动激发态氮分子的粒子数浓度不再变化,电子激发态的氮分子、原子和氧原子的粒子数浓度达到一峰值后开始降低;放电结束后的氧原子通过复合反应生成臭氧.约化场强升高,由于低能电子减少的影响,振动激发态氮分子的粒子数浓度降低,当约化场强由50 Td增加75 Td,100 Td时,粒子数浓度由3.83×10¹¹ cm^-3降至1.98×10¹¹ cm^-3和1.77×10¹¹ cm^-3,其他粒子浓度则相应增大. 关键词： 等离子体 约化场强 粒子演化 数值模拟     

OH number densities and plasma jet behavior in atmospheric microwave plasma jets operating with different plasma gases (Ar,Ar/N<Subscript>2</Subscript>, and Ar/O<Subscript>2</Subscript>)

OH radical number density in multiple atmospheric pressure microwave plasma jets is measured using UV cavity ringdown spectroscopy of the OH (A–X) (0–0) band at 308 nm. The plasma cavity was excited by a 2.45 GHz microwave plasma source and plasma jets of 2–12 mm long were generated by using three different plasma gases, argon (Ar), Ar/N₂, and Ar/O₂. Comparative characterization of the plasma jets in terms of plasma shape, stability, gas temperature, emission intensities of OH, NO, and N₂, and absolute number density of the OH radical was carried out under different plasma gas flow rates and powers at various locations along the plasma jet axis. With three different operating gases, the presence of OH radicals in all of the plasma jets extended to the far downstream. As compared to the argon plasma jets, the plasma jets formed with Ar/N₂ and Ar/O₂ are more diffuse and less stable. Plasma gas temperatures along the jet axis were measured to be in the range of 470–800 K for all of the jets formed in the different gas mixtures. In each plasma jet, OH number density decreases along the jet axis from the highest OH density in the vicinity of the jet tip to the lowest in the far downstream. OH density ranges from 1.3 × 10¹² to 1.1 × 10¹⁶, 4.1 × 10¹³ to 3.9 × 10¹⁵, and 7.0 × 10¹² to 4.6 × 10¹⁶ molecule/cm³ in the Ar, Ar/N₂, and Ar/O₂ plasma jets, respectively. The OH density dependence on plasma power and gas flow rate in the three plasma jets is also investigated.     

Determination of N and O – Atom and N2(A) Metastable Molecule Densities in the Afterglows of N2 and N2‐O2 Microwave Discharges

Early afterglows of N₂ and N₂‐O₂ flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atom and N₂(A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N‐atoms and measurements of NO and N₂ band intensities for O‐atoms and N₂(A) metastable molecules. By using N₂ tanks with 50 and 10 ppm impurity, it is determined in the afterglow an O‐ atom impurity of 150‐200 ppm. Variations of the N and O‐atom and N₂(A) metastable molecule densities are obtained in the early afterglow of N₂–(9·10^–5–3·10^–3)O₂ gas mixtures. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Experimental Study and Modelling of Formation and Decay of Active Species in an Oxygen Discharge

A microwave (2.45 GHz) oxygen discharge (3 hPa, 150 W, 50 mL.min^–1) is studied by optical emission spectroscopy of O(⁵P) (line 777.4 nm) and of the atmospheric system of O₂(head‐line 759.4 nm). Calibration of the spectral response of the optical setup is used to determine the concentrations of O(⁵P) and O₂(b). The concentration of the O(⁵P) atoms is in the range 108–109 cm^–3 and the concentration of the O₂(b) molecules is in the range 10¹⁴ – 2 × 10¹⁴ cm^–3 along the discharge tube. An attempt is made to simulate the experimental results by using coupling the Boltzmann equation, homogeneous energy transfer V‐V and V‐T, heterogeneous reactions on the walls (energy transfer and recombination of atoms) and a kinetic scheme (electronic transfer and chemical reactions). The Boltzmann equation includes momentum transfer, inelastic and superelastic processes and e‐e collisions. V‐V and V‐T transfer equations are obtained from the SSH theory and the kinetic scheme includes 65 reactions with 17 species [electrons e, ions O^– and O₂^–, fundamental electronic neutral species O(³P), O₂, O₂(X,v), O₃ and excited neutral species O₂(a), O₂(b), O₂(A), O(¹D), O(¹S), O(⁵P), O(4d ⁵D^o), O(5s ⁵S^o), O(3d ⁵D^o) and O(4s ⁵S^o)]. A fair agreement between experimental results and modelling is obtained with the following set of fitting values: – heterogeneous deactivation coefficient for O₂(b) γ = 2.6 × 10^–2; – rate constant of reaction [O(¹D) + O(³P) → 2 O(³P)] k₃₄ = 1.4 × 10^–11 cm³.s^–1; – electron concentration in the range 10¹⁰ – 10¹¹ cm^–3. Modelling shows that the recombination coefficient for oxygen atoms on the silica wall (range 1.4 × 10^–3 – 0.2 × 10^–3) is of the same order as the values obtained in a previous paper and that the ratio ([O] / 2 [O₂]initial) is about 33–50%. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Integral energy spectrum of primary cosmic rays at high energies

The integral energy spectrum of primary cosmic rays has been obtained. In the energy range (2.4×10³−1.1×10⁵ GeV), the spectrum of all nuclei is consistent with a power law of indexγ=1.55±0.06 and the flux of all nuclei is:N(⩾E ₀)⋍(5.1±1.8)×10⁻¹×E ₀ ^−1.55 particles/cm² sterad. sec., whereE ₀ is in GeV. The spectrum of primaryα-particles in the energy range (4.4×10³−4.8×10⁴) GeV is also consistent with a power law of indexγ=1.71±0.12 and the flux is:N(⩾E ₀)=(4.2±1.4)×10⁻¹×E ₀ ^−1.71 , particles per cm² sterad. sec, whereE ₀ is in GeV.     

MW-ECR PE-UMS等离子体特性及对Zr-N薄膜结构性能的影响

采用静电探针技术对微波电子回旋共振(MW-ECR) 等离子体进行了诊断,利用等离子体增强 非平衡磁控溅射(PE-UMS)法在常温下制备了Zr-N薄膜, 通过EPMA，XRD，显微硬度对膜的 结构和性能进行评价.实验结果表明，随氮气流量增加，总的等离子体密度从807×10⁹c m^-3增加到831×10⁹cm^-3然后逐渐减小为752×10 ⁹cm^-3；而N₂⁺密度则从312×10^{8< /sup>cm-3线性递增到335×109cm-3；电子温度变化 不大.对薄膜而言，随N₂+密度增大，样品中氮含量增加，而晶粒逐 渐变小，当样品中N/ Zr原子比达到14时，薄膜中出现亚稳态的Zr₃N₄相以及非晶相， 在更高氮流量下，整 个薄膜转变为非晶态.与此相应，薄膜硬度由最初的225GPa增大到2678GPa 然后逐渐减 小到1982GPa. 关键词： 氮化锆薄膜 ECR等离子体 磁控溅射 诊断}     

Determination of stratospheric H2O and O3 column densities from balloon altitude far infrared absorption spectra by a curve of growth method

Pure rotational lines of H₂O, Q branches of O₃ and single lines of O₃ in the far infrared absorption spectrum of the stratosphere, taken at an altitude of 29.1 km above Texas on 19 June, 1978 from a balloon-borne solar telescope equipped with a rapid-scanning Michelson interferometer, have been analyzed by a curve-of-growth method to yield good values of vertical column densities for these important minor constituents. In this mid-latitude atmosphere, vertical column densities of H₂O and O₃ were found to be 1.32(±0.39) × 10¹⁸ and 1.72(±0.55) × 10¹⁸ molecules cm⁻², respectively, the major contribution to the uncertainty coming from a correction to the overall spectral envelope necessitated by detector nonlinearity in this specific flight. The present data demonstrate the promise of this technique for the measurement of number density profiles of other important minor constituents, such as HCl, H₂O₂, NO₂, HO₂ which are expected to contribute to this spectrum in the stratosphere.     

129Xe contact shift in oxygen gas

We have determined the temperature dependence of σ₁ of ¹²⁹Xe in oxygen gas. These results were obtained by measurement of the resonance frequency of ¹²⁹Xe in gas samples of known densities in Xe and O₂. The shift of the resonance frequency due to Xe-Xe interactions has been measured in pure Xe gas samples with improved precision. This allows the determination of σ₁(Xe-O₂) by subtracting out the known effect of Xe-Xe interactions in mixed Xe-O₂ samples. σ₁(Xe-O₂) values are reported here for the temperature range 220 to 440 K. The values of σ₁(Xe-O₂) are adequately described by the polynomial function in p.p.m. amagat^-1 σ₁(Xe-O₂) = - 1·061 + 3·64 × 10^-3τ - 2·19 × 10^-5τ² + 9·58 × 10^-8τ³ - 2·08 × 10^-10τ⁴, where τ = (T - 300 K). It is found that the temperature dependence of σ₁(Xe-O₂) can be interpreted in terms of a contact interaction between Xe and the paramagnetic O₂ molecule.