Electron injection in laser wake-field acceleration by using near critical layers

A method for enhancing trapped electrons in the laser wake-field acceleration in dilute plasma is proposed. In this method, a thin layer with near critical density is placed in front of the dilute plasma. Upon interaction of this layer with a short and high power laser pulse, a relatively large number of layer electrons are injected in dilute plasma. Some of these electrons are trapped in the wake-field of transmitted laser pulse. Particle in cell simulation is used to demonstrate this method. Simulations showed that in addition to increasing the number of trapped electrons, this mechanism also reduces the energy broadening.     

Structure of water-in-oil microemulsions of AOT by infrared spectroscopy

Summary The structure of water in water/AOT/n-heptane reverse micelles has been studied as a function of the [H₂O]/[AOT] ratio (W) by using the absorption IR due to O−H stretching modes in the 3800–3000 cm⁻¹ range. The results show that the IR spectra can be expressed as a sum of contributions from bound- and bulk-like water. The fraction of water in the two ?regions? within the water pool was evaluated as a function ofW. The ?bound? water region seems to hold 3.5 water molecules (corresponding to 7 O−H oscillators) per AOT molecule and its formation is nearly complete atW>6. Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994.     

Total electron scattering cross-sections for O atoms: O2 and O3 molecules

Total (elastic+inelastic) cross sections fore ⁻-O,e ⁻-O₂ ande ⁻-O₃ scattering have been calculated at sample energies between 100 and 1000eV. The basice ⁻-O atom scattering amplitudes are obtained from the partial wave analysis with a complex optical potential. Thee ⁻-O₂ ande ⁻-O₃ cross-sections are obtained through the independent atom model. Oure ⁻-O₂ cross-sections reproduce the experimental data quite well. Adequate comparisons are made in all the three cases.     

Electronic spectra of quasi-regular heterostructures: simple versus realistic models

The electronic spectra of quasi-regular systems are investigated via simple one-dimensional, one-band models and compared with those obtained by means of realistic empirical tight-binding models, particularly for the Fibonacci sequence case.     

一台小型强流脉冲电子束加速器

本文介绍了一台供研究准分子气体激光器用的强流脉冲电子束加速器,其输出电压为500kV,束流50kA,脉冲宽度60ns,运行稳定,控制可靠,是一台小型可移动的电子加速器。文中还给出了它的结构参数,主要特点和调试结果。     

ENRICHMENT OF THE SPINDLE FIBER ATTACHMENTS FROM MOUSE LIVER CELL NUCLEI

Spindle fiber attachments (SFAs) were enriched in a fraction of nuclei isolated from mouselivers. The enrichment method combines sonication, treatment with 2 mol/L NaCl and highspeed centrifugation. SFA was enriched 27-fold on the average (n = 4) when measured byradioimmunoassay. The basic method offers opportunities for further increases of yield andfor the enrichment of SFA uf other vertebrates.     

高密度氩等离子体电子密度的计算

用屏蔽氢离子模型计算了冲击压缩产生的温度T～2.0eV、密度ρ～0.01g/cm3～0.49g/cm3范围内氩等离子体的电子密度,探讨了不同温度、密度范围内的高密度氩等离子体中粒子之间相互作用对电子密度的影响.     

Effect of the RE ionic size on the REBa2Cu3O7−δ ceramics oxygenated at 250 bar

REBa₂Cu₃O_7−δ (RE=Ho, Y, Dy, Gd, Sm, Nd) ceramics have been oxygenated at 1 bar pressure (LP) and, subsequently, at 250 bar (HP). Despite the noticed slight uptake of oxygen (up to the value of 0.07), after the HP processing, the electrical resistivity (ρ) of all samples increased, what was attributed to the deterioration of the grain boundaries. The increase of ρ was much more pronounced and also accompanied by a change of ρ(T) characteristics into a semiconducting-like one in the case of 123 compounds based on REs which ionic size is large enough to form solid solutions of RE_1+xBa_2−xCu₃O_y type (i.e., RE=Gd, Sm, Nd). As shown in the literature, such 123s usually contain more structural defects. Thus, the observed effect may be attributed to the migration of the defects induced by the elevated pressure oxygenation. The defects could be trapped near the grain boundaries resulting in the deterioration of their electrical properties. The possible role of the oxygen-pressure-induced modifications of the impurity phases has been also discussed. The materials obtained in the HP process may be regarded as 3D arrays of superconducting grains coupled by the Josephson junction or weak links only, as was shown in a tunneling experiment.     

Co2+:ZnAl2O4晶体电子光谱及其2E态双重谱线结构的Jahn-Teller效应研究

在中间场耦合图象中,利用Racak不可约张量算符法和Wigner－Eckart定理,建立了3d⁷(C_3v)电子组态的完全能量矩阵;利用该矩阵研究了Co²⁺:ZnAl₂O₄晶体的电子光谱,理论与观测十分吻合．首次定量地解释了2E态的双重谱线结构,并从理论上预言了⁴A₂基态2.93cm^-1的零场分裂(ZFS)．研究结果定量地表明,Jahn－Teller效应所致Co²⁺:ZnAl₂O₄晶体Co²⁺中心局域结构的畸变假设是合理的．