三倍频激光等离子体X射线转换研究

利用“星光Ⅱ”高功率激光装置三倍频激光（波长０.３５μｍ,能量５—９０Ｊ,焦斑直径约２００μｍ,脉冲宽度４００—８００ｐｓ）辐照多种材料（Ｃ,Ａｌ,Ｃｕ,Ａｕ）靶,对于不同激光功率密度,研究软Ｘ射线转换和发射能谱．结合０.３５μｍ激光辐照Ａｌ靶的质量烧蚀率和等离子体喷射速度与激光功率密度的定标关系进行数值模拟,对于激光功率在１０^１３—１０^１５Ｗ／ｃｍ²理论模拟结果与实验结果符合得很好 关键词：     

Physics issues associated with low-β plasma generators

Kinetic aspects of MHD generators are explored by examining the propagation of dense, low-β streams of plasma. Three situations are considered: the basic principles of plasma-stream propagation, the propagation of plasma streams into vacuum, and the propagation of plasma streams into ambient plasmas. These three situations are analogous to plasma generators, plasma generators with vacuum loads, and plasma generators with plasma loads. Kinetic (microphysics) aspects include oscillations of the generator plasma, the effects of diocotron instabilities, the acceleration of particles, the starvation of current systems, and plasma-wave production     

等离子体屏蔽效应对原子能级和振子强度的影响

利用Debye模型,研究了等离子体屏蔽效应对热等离子体中原子能级和振子强度的影响.通过在MCDF模型中引入等离子体屏蔽效应,计算了MnXXII-BrXXII等11个类Be离子在等离子体环境下2s²—［2s_1/2,2p_1/2］₁和2s²—［2s_1/2,2p_3/2］₁跃迁的能级和振子强度.计算结果表明,等离子体屏蔽效应使得类Be离子2s²—［2s_1/2,2p_1/2］₁跃迁的激发能量增大,从而导致谱线蓝移现象;并且随着屏蔽效应的不断增强,蓝移的程度会逐渐加大.屏蔽效应对于2s²—［2s_1/2,2p_3/2］₁跃迁的振子强度也有类似的影响. 关键词： Debye 等离子体屏蔽 跃迁能级 振子强度     

Start-stop control strategies for heat recovery in multi-zone water-loop heat pump systems

A study is made to determine the energy saving potential of a start—stop controlled water-loop heat pump (WLHP) system. The physical model consists of individual heat pumps for each zone, a two-pipe water-loop system (with and without a storage tank), a boiler and an evaporative cooler. The overall system consists of four input energy controllers and an equal number of mass flow rate controllers. A simple start-stop control strategy for the system is developed. Results showing the typical daily operation of the system under changing heating and cooling loads are presented. A method for selecting the appropriate limits for loop water temperature which results in energy savings is given.     

Heat-transfer mechanisms in solar flares. 1: Classical and anomalous heat conduction

In the context of the problem of energy transport in solar flares, simplified analytical models have been developed that describe plasma heating in the solar atmosphere by heat fluxes from the super-hot (T _e ≳ 10⁸ K) reconnecting current layer. It is shown that the applicability conditions of common heat conduction produced by Coulomb collisions of electrons in plasma are not fulfilled in solar flares. The heat flux calculated using the classical Fourier’s law proves to be significantly higher than the real energy fluxes known from modern multi-wavelength observations of flares. The so called anomalous flux produced by interaction of free electrons with ion acoustic waves in a plasma is critically analyzed. The question of what the dominant mechanism of heat transfer in solar flares is requires additional consideration [1].     

部分电离稠密氦等离子体物态方程的自洽变分计算

稠密氦在高温高压下将会发生电离, 电离能会因为原子、离子以及电子之间的相互作用而降低. 考虑He，He⁺，He²⁺，e之间的相互作用, 通过粒子化学势平衡得到非理想的电离平衡方程，用自洽流体变分过程对方程求解, 进而对自由能求导获得体系的热力学状态参量. 模型计算结果与已有的实验和理论计算相一致. 用此模型预测密度10^-3—10^0.3 g/cm³和温度4—7 eV范围的物态方程, 获得了压力在500　GPa以内的理论数据. 计算表明粒子间的非理想相互作用引起的电离能降低是出现压致电离现象的主要原因，在高温高密度物态方程的计算中必须考虑粒子间非理想相互作用对电离能修正的影响. 关键词： 氦 物态方程 部分电离等离子体 自洽变分     

Adsorption,diffusion and self-diffusion on tungsten surfaces with adsorbed palladium

The influence of a Pd adsorption layer on the surface self-diffusion of tungsten has been measured using a field emitter technique. By adsorption of 1.2 × 10¹⁵ Pd atoms/cm² — measured by high energy ion backscattering — the surface self-diffusion energy decreases from 70 to 54 kcal/mole, and the diffusivity from 0.95 to about 0.2 cm²/s, which corresponds to an increase of the diffusion coefficient by a factor 40 at 1600 K and 80 at 1400 K. Furthermore are determined (1) adsorption lifetimes in adsorption-desorption equilibria, (2) the isosteric adsorption heat (103 kcal/mole), and (3) the coefficient of Pd surface diffusion on W resulting in diffusion energies of 32 kcal/mole around (001) and 17 kcal/mole around (111).     

Effect of convection and heat conduction on the laser gain in a nonequilibrium recombinational hydrogen wall plasma

The effect of a conducting body with a large heat capacity on the thermal state of a hydrogen plasma in the boundary surface layer is analyzed. It is shown that, under certain conditions, the energy accumulated in the plasma within the boundary layer can be efficiently transferred to the conducting body; this leads to plasma overcooling. The mathematical model of plasma incorporates mechanisms for convective heat exchange and heat conduction. The possibility is analyzed of the existence of nonequilibrium recombination states with inverse population in the overcooled wall plasma. It is shown that the maximum gain (a few tenths of cm^?1) on hydrogen nuclei is achieved at the 3-2 transition for the following initial parameters: the plasma pressure is 1–3 atm, the plasma temperature is 0.5 eV, the tungsten surface temperature is 300 K, and the body radius is 0.5–1.0 m.     

Characteristic of Disruption on HL-2A Tokamak

The tokamak disruption is a dramatic event in which the plasma confinement is suddenly destroyed. Detailed experimental studies of disruptions have been made in many machines. During disruption, the plasma current and plasma thermal energy content collapse in an uncontrollable way, thereby applying mechanical forces and heat loads onto the vacuum vessel components. For that reason, the disruptions in a tokamak must be investigated and the physical processes leading to and occurring at the disruption need to be understood.     

高离化类铍离子2s21S0—2s2p3P1(Z=10—103)自旋禁戒光谱跃迁

利用全相对论性多组态Dirac-Fock平均能级(MCDF-AL)方法系统地计算了高离化类铍离子自 旋禁戒2s^{2 1}S₀—2s2p³P₁(Z= 10—103)跃迁的能级间隔和跃迁概率,计算中考虑了重要的核的有限体积效应,Breit修正 和QED修正,所得结果和最近的实验数据及理论计算值进行了比较,结果表明：高原子序数 的高荷电离子的自旋禁戒跃迁的跃迁概率和中性原子的电偶极E1的相当,在ICF和MC 关键词： 高离化态 跃迁概率     

Modification of metallic materials by processing with high-temperature pulsed plasma streams

A review is given of investigations of the modification of metallic materials by processing them with high-temperature pulsed plasma streams having incident power densities in the range (3–100)×10⁹ W/m² with pulse durations of between 2–3 and 100 µsec. The main experimental results are presented on changes in the microstructure, the mechanical and tribological characteristics, the corrosion resistance, and the radiation-induced erosion when the modified materials are irradiated with ions. An analysis of these results shows that processing with high-temperature pulsed plasma streams is a comprehensive method for changing in a controlled manner the structural-phase state and various operational properties of materials, the extent of the change being determined by the irradiation conditions (the power density of the incident stream, the type of plasma, etc.), the type of material, and its previous processing.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 109–126, May, 1993.     

Initiation of ecton processes by interaction of a plasma with a microprotrusion on a metal surface

Evolution of rapid (～10 ns) Ohmic overheating of a microprotrusion on a surface in contact with a plasma by emission current is studied taking into account the energy carried by plasma ions and electrons, as well as Ohmic heating, emissive source of energy release (Nottingham effect), and heat removal due to heat conduction. Plasma parameters were considered in the range of n = 10¹⁴?10²⁰ cm^?3 and T _e = 0.1 eV?10 keV. The threshold value of energy transferred to the surface from the plasma is found to be 200 MW/cm²; above this value, heating becomes explosive (namely, an increase in the temperature growth rate (δ² T/δt ² > 0) and in passing current (δJ/δt > 0) is observed in the final stage at T ～ 10⁴ K and j ～ 10⁸ A/cm²). In spite of the fact that Ohmic heating does not play any significant role for plasmas with a density lower than 10 18 cm^?3 because the current is limited by the space charge of electrons, rapid overheating of top of microprotrusion is observed much sooner (over a time period of ～1 ns) when the threshold is exceeded. In this case, intense ionization of vapor of the wall material leads to an increase in the plasma density at the surface, and the heating becomes of the Ohmic explosion type. Such conditions for the formation of a micr?xplosion on the surface and of an ecton accompanying it can be created during the interaction of a plasma with the cathode, anode, or an insulated wall and may lead to the formation of cathode and anode spots, as well as unipolar arcs.     

用20—1020 keV单能质子刻度CR-39固体核径迹探测器

用北京师范大学2×1.7MV串列加速器和400 kV高压倍加器产生的20—1020 keV单能质子束对CR-39固体核径迹探测器进行了刻度.为了保证质子的单能性和固体核径迹探测器上径迹密度不能超过10⁶/cm²的要求,对两台加速器分别采用了不同方法控制质子辐照数量.在串列加速器上采用了狭缝加转盘的方法,在高压倍加器上采用了100 ns单次高压脉冲扫描束流的方法,既保持了质子的单色性,又达到了质子注量小于10⁶/cm²的 关键词： 单能质子 固体核径迹探测器 CR-39     

Optimization of steam-turbine power unit of a coal mini-HPP with variable schedule of heat and electric energy loads

The technique for optimization of parameters of a power unit of a gas-turbine small-size heat and power plant was developed with regard for seasonable nature of heat and electric energy loads; the approach uses linear versions of dependency of outlet parameters on the inlet parameters. A mathematical model of the energy unit of a mini-HPP was developed. Optimization calculations for a coal gas-turbine mini-HPP were carried out for several optimization criteria: minimal revenue from the produced heat and electric energy (at different levels of fuel price), minimum of fuel consumption during year, and minimal investment at a given internal return rate.     

Application of high velocity streams of dense plasma for the creating of high adhesive compounds of chemically noninteracting metals

The work presents the experimental results of investigation of the possibility of the creating of high adhesive compound of chemically noninteracting metals by means of pulse streams of high temperature dense plasma. The 4 kJ plasma focus installation was used as a source of pulse streams of plasma. In the experiment assemblies of Cu–W and Pb–Fe samples were used. The deep penetration of atoms Cu and Pb accordingly in W and Fe was found. The mechanisms of the penetration of chemically neutral atoms into a material of the target can be connected with the following processes: the energy transfer from plasma pulse to implanting atoms, the origin and distribution of shock waves in the material of a target, and also the Rayleigh-Taylor instability of the border of two combining materials.     

喷气式Z箍缩等离子体辐射软X射线能谱的研究

研制了一台五通道ROSS-FILTER-PIN软X射线能谱仪，能谱范围为0.28—1.56keV.它由5个连续能段组成，每个能段的起止边由罗斯滤片对(ROSS-FILTERS)的L或K吸收边确定.罗斯滤片对的厚度通过优化计算得到，为了使每个通道的灵敏区外响应(即所测能段外响应)与通道总响应之比最小，在滤片对的第二滤片上镀上了一定厚度的第一滤片材料；为了缩减滤片表面积以增强低能滤片的抗冲击能力及方便滤片加工，能谱仪采用了小探测面积的PIN探测器(1mm²).借助此能谱仪，测量得到了喷气式Z箍缩(Z-pinch)等离子体辐射软X射线能谱的分布，并研究了软X射线产额随箍缩状况的变化趋势. 关键词： Z箍缩等离子体 罗斯滤片 软X射线能谱     

HL-2M装置常规偏滤器与雪花减偏滤器热工水力分析对比

采用SOLPS程序模拟预测HL-2M装置常规和雪花减偏滤器靶板上的热通量。当流入边缘等离子体区域的热功率约为10MW时,利用CFX/ANSYS软件分析这两类偏滤器各结构、冷却水温度分布及形变和热应力分布情况。结果表明:等离子体总功率相同,雪花减偏滤器靶板上的最高温度比常规偏滤器低169℃;雪花减偏滤器结构所承受的最大热应力和形变比常规偏滤器低约3/7。不改变热负载剖面分布,按一定比例提升热流密度或延长放电时间,雪花减偏滤器体现出比常规偏滤器靶板温升低、冷却水温均衡等优点。因此,雪花减偏滤器能处理更多流进偏滤器区域的热能,有效地降低偏滤器工程设计要求。     

Production of ion and electron streams by pulsed-laser ablation of Ta and Cu

A Nd:YAG laser with 10⁹ W/cm ² pulse intensity, operating at 532 nm wavelength, is used to ablate Ta and Cu targets placed in vacuum. The ablation process generates a plasma in front of the target surface, which expands along the normal to target surface. The ion and electron emissions from the plasma were measured by Faraday cups placed at different angles with respect to the normal to target surface. In the range of laser intensities from 10⁷ to 10⁹ W/cm², the fast electron yield is lower than the ion yield and it increases at higher laser intensities. The ablation threshold, the emission yield, the ion and electron average energies and the plasma ion and electron temperatures were measured for ion and fast electron streams.     

Numerical research of stream analysis on helical baffles heat exchangers

In this paper, the numerical simulations for a helical baffles heat exchanger and a segmental baffles heat exchanger with component clearance are performed to reveal the features of leakage streams and their effect on heat exchanger performance. Helical baffles heat exchanger models with four different angles and segmental baffles heat exchanger model were established and calculated via Gambit and Fluent software. The results reveal that the heat exchanger with a 40° helix angle shows the best comprehensive heat transfer performance in turbulent state, and the heat exchanger with a 50° helix angle shows better comprehensive heat transfer performance in laminar flow state. The leakage streams proportion of the helical baffles heat exchanger varies from 5.5% to 6.1%, compared with the leakage streams proportion changes from 16.6% to 21.0% in the segmental baffles heat exchanger. In both turbulent flow state and laminar flow state, with the rise of shell-side Reynolds number, the main spiral stream B proportion decreases and the leakage streams proportion increases in the segmental baffles heat exchanger, while the stream B proportion increases and the leakage streams proportion decreases in helical baffles heat exchanger. The proportion of stream B increases with the increase of the helix angle β and the proportions of leakage streams decrease with the increase of β. The proportion of the tube-baffle leakage stream A increases in radial direction. Both the proportion of stream A and that of the baffle-shell leakage stream E fluctuate in the intermediate zone in axial direction; the stream A proportion decreases at the inlet and outlet zone, while the stream E proportion increases at the inlet and decreases at the outlet zone. The results of this paper could be of great significance in the optimal design and manufacture of the helical baffles heat exchanger.