Partition Functions for Diatomic Molecules in Plasmas out of Thermal Equilibrium

Two calculation methods on the partition functions for diatomic molecules in plas- mas out of thermal equilibrium are reported. A Boltzmann distribution for the electronic, vi- brational and rotational quantum levels is assumed in the two calculation methods. The results obtained by two methods are displayed for four sorts of diatomic molecules, 02, N2, OH and NO, that are present in humid air plasmas. The calculation method of density for the electronically excited states is developed. Finally, a method to calculate the partition functions for simulating the non-normalized diatomic spectra is discussed.     

Diagnostics of Rovibrational Distribution of H2 in Low Temperature Plasmas by Fulcher-α band Spectroscopy - on the Reaction Rates and Transition Probabilities

A novel fitting procedure is proposed for a better determination of H2 rovibrational distribution from the Fulcher-a band spectroscopy. We have recalculated the transition probabilities and the results show that they deviate from Franck-Condon approximation especially for the non-diagonal transitions. We also calculated the complete sets of vibrationally resolved crosssections for electron impact d3∏u- X3∑g transition based on the semi-classical Gryzinski theory.An example of experimental study confirms that current approach provides a tool for a better diagnostics of H2 rovibrational distribution in electronic ground state.     

Vibrational Temperature of Excited Nitrogen Molecules Detected in a 13.56 MHz Electrical Discharge by Sheath-Side Optical Emission Spectroscopy

Optical emission spectroscopy parallel to the axis of a low-pressure radio-frequency discharge in nitrogen was realized,i.e.end-on instead of customary side-on measurements.A specially designed optical feedthrough was fabricated and installed co-planar with the anode electrode,allowing non-invasive observations perpendicular to the plasma sheath.The principal excited species flowing towards the grounded electrode were identified and,by assuming Boltzmann distributions,the vibrational temperature of the molecules on the X1∑+g and C3Πu levels was estimated under various operating conditions.     

Study on the Two-Dimensional Density Distribution for Gas Plasmas Driven by Laser Pulse

We perform an experimental study of two-dimensional(2D) electron density profiles of the laser-induced plasma plumes in air by ordinarily laboratorial interferometry. The electron density distributions measured show a feature of hollow core. To illustrate the feature, we present a theoretical investigation by using dynamics analysis. In the simulation, the propagation of laser pulse with the evolution of electron density is utilized to evaluate ionization of air target for the plasma-formation stage. In the plasma-expansion stage, a simple adiabatic fluid dynamics is used to calculate the evolution of plasma outward expansion. The simulations show good agreements with experimental results, and demonstrate an effective way of determining 2D density profiles of the laser-induced plasma plume in gas.     

Spectroscopic Studies on Impurity Transport of Core and Edge Plasmas in LHD

Spectroscopic diagnostics have been extensively developed for studies of impurity and neutral particle transports at core and edge plasmas in LHD. Diagnostics of core plasmas are similar to a tokamak case, i.e., Zeff from visible bremsstrahlung, K-x-ray measurements from xray spectroscopy using Si（Li） detectors and a compact crystal spectrometer, and high-Z impurity diagnostics from VUV spectroscopy using a flat-field EUV spectrometer. A combination of impurity pellet injection and visible bremsstrahlung is an active tool for determination of the diffusion coeffici＇ent D and convective velocity V. Using this tool the spatial structures of D and V are obtained and discussed with a neoclassical effect. On the other hand, the spectroscopic method for edge diagnostics is considerably different from the tokamak case because of the existence of a thick ergodic layer in addition to the z-points necessarily included into the diagnostic chord view. In order to break this negative situation, Zeeman and polarization spectroscopy are adopted to LHD edge plasmas. As a result, 2-dimensional emission contours of HeI and Ha are successfully obtained. Laser absorption spectroscopy is tried to measure hydrogen neutrals directly. Radial profiles of edge impurities are also measured with a mirror-assembled 3 m VUV spectrometer. Recent results of and progress in LHD spectroscopy are briefly reviewed.     

Kinetics of Hydrogen Molecules in MAGNUM-PSI

Results from simulations of plasma and neutrals under conditions predictively characterizing the detached plasma regime in the linear machine MAGNUM-PSI are presented. The relaxation of the vibrationally excited hydrogen molecules is investigated in order to establish a relation between their relaxation and dwell times, and the role of the varions mechanisms of the molecular vibrational kinetics. Tile results obtained show that the individual vibrational states have to be inclllded in the transport code for neutrals as distinct species, since the relaxation time of tile vibrational states is sufficiently longer than the typical dwell time of hydrogen molecules in the detached plasma region. The parameters of plasma and neutrals are affected by the transport of the vibrationally excited hydrogen lnolecnles. Furthermore. the rate of molecular reconlbination is overestimated by a factor of - 5 provided that the transport of ilydrogen molecules only in their ground vibrational state is considered. The role of the various processes of vibrational kinetics is studied. The vibrational excitation through singlet electronic states ires a strong influence on the molecular densities for levels with vibrational quantum numbers v≥ 5. Vibration-vibration （V-V） collisions between vibrationally excited hydrogen molecules and vibration-translation （V-T） collisions between vibrationally excited hydrogen molecules and ground state molecules and atoms are of nlinor importance in MAGNUM-PSI.     

流动沸腾汽泡脱离直径尺寸分布研究

沸腾是一个复杂的换热过程,大量实验表明,不同核化点的脱离直径存在区别,即使在同一工况下,同一核化点产生的汽泡脱离直径也会大小不一,因此汽泡尺寸分布不可忽略。尽管目前已有较多用于汽泡平均尺寸的计算关系式,但对于尺寸分布的研究仍较少。因此,本文针对流动沸腾下汽泡脱离直径的尺寸分布进行研究,对比常用的伽马函数和正态分布函数描述这一分布时的准确度,确定概率函数后,再对概率密度函数中两个重要的参数均值和标准差进行分析,最后得到一套预测不同工况下汽泡尺寸分布的关系式,该关系式准确度较高,并考虑了壁面过热度、质量流速等因素的影响。     

Contrasting Behaviours of AC and DC Excited Plasmas in Contact with Liquid

A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations is detailed in this paper. All plasmas studied here are shown to be glow discharges. This study is based on measurements of several key parameters, including electrical energy, optical emission intensities of active species, rotational and vibrational temperatures, and temperatures of the needle and liquid electrodes. AC plasmas can produce 1.2～5 times higher excited state active species than DC plasmas under the same dissipated power. AC excited liquid plasmas have the highest energy utilization efficiency among the three systems (AC excited plasmas, DC excited plasmas with water anode and DC excited plasmas with water cathode); most of the energy is used to produce useful species rather than to heat the electrodes and plasmas.     

Comparative Study of Decomposition of CCl4 in Different Atmosphere Thermal Plasmas

Decomposition of carbon tetrachloride was studied theoretically in the most commonly used thermal plasma atmosphere such as H2, N2, O2 and water steam. A code developed by the National Aeronautics and Space Administration （NASA） was adopted to calculate the chemical equilibrium distribution and energy consumption of the decomposition of CC;4 in the H2, N2, O2 and water steam atmosphere thermal plasma respectively, with a temperature range of 500 K to 5000 K. In the neutral condition （H2, N2, atmosphere） formation of solid carbon was observed and in the oxygen-atmosphere （O2 and water steam） solid carbon formation disappeared through controlling the ratio of C/O. This indicates that the formation of polycyclic aromatic hydrocarbons （PAHs） is impossible theoretically. The energy consumption in the N2 atmosphere was much higher than that in the H2, O2 and water steam atmosphere at 1500 K.     

Electrochemical calorimetric studies on the electrolysis of water and heavy water (D2O)

Electrochemical calorimetric studies were carried out in H₂O and D₂O using Pd and Pt cathodes with LiOD(H) electrolytes. Two types of calorimetric cell designs were used in this attempt to detect excess enthalpy during the electrolysis of D₂O using Pd cathodes. Control experiments were run side by side using water and/or Pt cathodes. A variety of pretreatments and cathode attachment schemes were employed. No discernible differences were detected between the Pd/D₂O cells and the controls, regardless of conditions. For example, using one type of calorimetric cell and conditions, the mean value for the excess enthalpy was 6.5±4% in D₂O compared to 7.5±7% in H₂O. For the other type cell, the mean result for one series of experiments was 0±4% compared to Pt cathodes.     

激光与陡峭密度梯度等离子体相互作用电子加热机制研究

本文利用二维PIC模拟了超短超强激光与陡峭密度梯度等离子体相互作用过程中电子的加热机制。结果表明,在10²³ W/cm²的超短超强激光场与陡峭密度分布的μm级等离子体层相互作用的过程中有质动力加速、大幅度等离子体尾场及共振吸收共同决定了电子束的加速与加热。     

Comparison of 2D Hybrid Simulational and Experimental Results for Dual-Frequency Capacitively Coupled Argon Plasmas

A two-dimensional hybrid simulation scheme is proposed to study the characteristics of dual-frequency (DF) capacitively coupled plasma (CCP) discharge based on the geometry of real device. Given the experimental parameters for argon plasma, the output from the fluid module such as ion density, number flux, electron temperature and the Monte-Carlo collision (MCC) results of ion energy distribution function (IEDF) as well as electron energy distribution function (EEDF) are obtained and discussed in detail. A novel complete floating double probe is designed to measure both density and temperature of electron and a quadrupole mass spectrometer is also equipped for IEDF investigations. The measurements on the density of bulk plasma, electron temperature and IEDF agree well, qualitatively, with the simulated results. A comparison with experimental results indicates that, since the structure of real device is taken into account, this model is capable of describing the global dynamic characteristics occurred in DF-CCP and presenting more reliable results than the model with an ideal chamber structure.     

环形燃料流量分配比范围研究

针对环形燃料双冷却通道的特殊结构形式,基于计算流体力学（CFD）方法建立了单棒精细化流固热耦合数值计算模型,通过计算内外包壳与内外通道冷却水的温度场分布对环形燃料流量分配比（φ）的取值范围进行了研究。计算结果表明：内外包壳温差与内外通道出口温差均随着φ的增大而减小;当φ≤0.72时,外包壳内部径向温度曲线斜率在包壳表面附近出现陡变;0.86≤φ≤1时,包壳内部温度变化均匀,无温度陡变现象,且内外包壳温差小于8 ℃,内外通道出口冷却水温差小于10 ℃。综合考虑环形燃料双侧冷却优势的充分发挥和包壳的机械安全性,确定了φ的取值范围为0.86～1。     

Diagnosis of Electronic Excitation Temperature in Surface Dielectric Barrier Discharge Plasmas at Atmospheric Pressure

The electronic excitation temperature of a surface dielectric barrier discharge （DBD） at atmospheric pressure has been experimentally investigated by optical emission spectroscopic measurements combined with numerical simulation. Experiments have been carried out to deter- mine the spatial distribution of electric field by using FEM software and the electronic excitation temperature in discharge by calculating ratio of two relative intensities of atomic spectral lines. In this work, we choose seven Ar atomic emission lines at 415.86 nm [（3s^23p^5）5p →（3s^23p^5）4s] and 706.7 nm, 714.7 nm, 738.4 nm, 751.5 nm, 794.8 nm and 800.6 nm [（3s^23p^5）4p → （3s^23p^5）4s] to estimate the excitation temperature under a Boltzmann approximation. The average electron energy is evaluated in each discharge by using line ratio of 337.1 nm （N2（C^3Пu →B3Пg）） to 391.4 nm （N2^＋（B2 ∑u^＋→ ∑g^＋））. Furthermore, variations of the electronic excitation tempera- ture are presented versus dielectric thickness and dielectric materials. The discharge is stable and uniform along the axial direction, and the electronic excitation temperature at the edge of the copper electrode is the largest. The corresponding average electron energy is in the range of 1.6- 5.1 eV and the electric field is in 1.7-3.2 MV/m, when the distance from copper electrode varies from 0 cm to 6 cm. Moreover, the electronic excitation temperature with a higher permittivity leads to a higher dissipated electrical power.     

235UF6和238UF6同位素分子共振能量转移研究

本文利用长程力碰撞理论计算了²³⁵UF₆和²³⁸UF₆同位素分子间ν₃振动能量的近共振碰撞转移过程,得到了不同温度下共振函数随能量差变化的曲线,发现共振函数的宽度随温度的升高而增大。计算了不同温度下共振转移几率和共振转移速率,发现它们随温度的升高而减小。可见,²³⁵UF₆和²³⁸UF₆同位素分子的平动会降低其共振转移几率和共振转移速率,这为激光光化学法分离铀同位素提供了理论依据。     

非稳态条件下平板通道内层流速度分布研究

针对平板通道内非稳定条件下层流的速度分布特点及阻力特性进行了理论和实验研究。基于非稳态条件下平板通道内的数学模型,分析了初始速度分布、压力梯度变化率、加（减）速时间对瞬时速度分布的影响。结果表明：非稳态层流的速度分布特点与通道尺寸、流体性质、压力梯度变化率和加速时间有关;相同截面平均流速条件下,加速情况下的中心流体速度小于稳态的,且加速流动使沿程流动损失增加,减速流动则恰好相反,实验验证结果与理论分析结果符合良好。     

水冷固态增殖包层模块冷却剂管系流量分配研究

包层是磁约束聚变堆中实现氚增殖和能量导出的重要部件,针对包层模块中,由于复杂的串并联流道结构所导致的冷却剂流量分配不均匀问题,采用一维热流体流动分析软件Flowmaster,建立了水冷固态增殖包层子模块的冷却剂流道结构模型。对运行工况下包层冷却剂流量分配进行模拟,并与相关试验以及模拟结果进行比对。模拟结果表明,所建立的子模块一维模型各部分冷却剂温升和压降均与设计值吻合,模型能够准确的描述包层冷却剂流动特性。在稳态运行工况下,包层子模块侧壁支管出现较为明显的流量分配不均匀现象,流量最大值与最小值偏差达到5%。位于侧壁上下两端的集合管对流量分配均匀性起重要作用,保持矩形集合管横截面积不变,横截面长宽相等时流量分配最为均匀。当集合管采用不同形状设计时,圆形管道流量分配均匀性要好于矩形管道。     

A Dip Structure in the Intrinsic Toroidal Rotation Near the Edge of the Ohmic Plasmas in EAST

Ion＇s toroidal velocity, vt, in both the outermost 4 cm of the confined region and the scrap-off layer of Ohmic L-mode plasmas in EAST was measured using Mach p...     

不同湍流模型对氢气分布影响的数值研究

研究严重事故下安全壳内氢气分布有利于评估氢气风险。本文采用三维CFD方法对THAI装置HM2试验进行建模,并分别使用代数模型和k-ε模型模拟氢气分层形成以及破坏过程。分析结果表明,CFD模拟结果与实验数据基本符合,在模拟中可观察到氢气分层现象的形成以及水蒸气对氢气分层的逐步破坏与混合过程;在氢气注射阶段,代数模型和k-ε模型的模拟结果接近,能够反映氢气浓度分层的形成过程;在水蒸气注射阶段,代数模型基于半经验的混合长度理论,在模拟装置较复杂几何结构内水蒸气流动对氢气分层的破坏作用时并不十分理想,标准k-ε模型对装置各测点氢气浓度达到一致的时间预测与试验结果较为接近。