Development and characterisation of an XeCl excimer laser-generated soft-X-ray plasma source and its applications

Summary A large-aperture, long-pulse XeCl excimer laser has been used to generate a soft-X-ray plasma source. Several laser optical configurations have been employed to optimise X-ray emission, including positive-branch unstable resonators and injection by seeding the gain region of the laser with a small commercial excimer laser, resulting in power densities in the range 10¹²–10¹⁴ W cm⁻². The characteristics of the plasma source for each different laser configuration and for different target materials are investigated. The most suitable source conditions (spectral energy distribution, time duration, etc.) for specific applications are discussed. Supported by the Royal Society, UK. Supported by INFM, Italy.     

电磁波在大气层人造等离子体中的衰减特性

利用洛沦兹模型来研究大气层人造非均匀等离子体的电磁响应特性,讨论了电磁波频率、等离子体密度及电子碰撞频率对电磁波衰减特性的影响.结果表明,电磁波在长波长区域及等离子体密度大时,其能量衰减越快.当等离子体密度高时,电子温度越低,大气层高度越高,电磁波的能量衰减越快. 关键词： 电磁波 大气等离子体 能量衰减     

稠密Ar等离子体不透明度的计算

用屏蔽氢离子模型计算了冲击压缩产生的温度T～1.8 eV,密度ρ～0.0044 g/cm3稠密氩等离子体随光子能量变化的辐射不透明度,并与实验作了比较,探讨了冲击压缩产生的稠密等离子体中自由-自由吸收、束缚-自由吸收和束缚-束缚吸收对不透明度的贡献.计算结果表明,对冲击压缩产生的稠密等离子体,自由-自由吸收对不透明度的贡献非常大,特别当光子能量较低时(hv～2.0 eV )自由-自由吸收为不透明的主要部分,因此较好地计算自由-自由吸收项对冲击压缩产生的稠密等离子体不透明度的研究是非常重要的.     

Corelationship between local structure and water purifying ability of iron-containing waste glasses

A relationship between the structure and water purifying ability of waste glass prepared from household garbage and Fe₂O₃ was examined by ⁵⁷Fe-Mössbauer and induced coupled plasma (ICP) measurements. From the Debye temperature of waste glass, Fe^II proved to be loosely bound in the glass network as a network modifier. Dissolution amount of Fe^III into artificial drain can be controlled from 0.14 to 0.35 mg/l by changing the Fe₂O₃ content. It proved that chemical oxygen demand (COD) decreases in proportion to the content of Fe^III, indicating that iron causes decomposition of organic and phosphorus compounds.     

超短脉冲激光在均匀等离子体中的一维演化

研究了均匀等离子体中超短脉冲激光在传输过程中的脉宽、峰值功率随时间，空间变化的解析式，结果表明，对于２５ｆｓ左右的超短脉冲，由等离体色散引起的脉宽变长及峰值功率降低效应是明显的。     

非同轴双束激光产生的等离子体辐射

采用非同轴双束激光，可得到时空差可控的二束不同性质的等离子体，实现在绝对同等条件下研究多束等离子体辐射的空间非均匀性和等离子体喷射对线加宽的影响。实验结果显示出在最简单的实验装置上实现等离子体强Ｘ射线泵浦Ｘ射线激光方案的可能性。     

掠入射驱动产生x射线激光的数值模拟

利用一维流体力学数值模拟程序MEDUSA和原子物理程序包，以类镍钼189nm x射线激光为例，对掠入射驱动x射线激光方案进行了研究.掠入射驱动x射线激光方案可以通过调整掠入射角来选择适合的增益区间.与正入射驱动方案相比，掠入射驱动方案加强了驱动激光在增益区内的吸收，提高了驱动激光向x射线激光的转换效率.模拟结果与实验结果符合较好. 关键词： x射线激光 掠入射辐照 激光等离子体     

用于X射线时空分辨测量的弯晶谱仪

为了测量激光聚变产生的0.2～0.37 nm范围内的等离子体X射线, 设计了一种基于空间和时间分辨的聚焦型弯晶谱仪. 将在700℃时弯曲后的LiF(2d＝0.403 nm)晶体作为色散元件, 布喇格衍射角的变化范围为30～67.5°, 弯晶粘贴在离心率和焦距分别为0.9586和1350 mm的椭圆形不锈钢基底上. 利用弯晶谱仪配X光CCD相机在星光Ⅱ激光(0.35 μm, 60～80J, 700 ps)装置上摄取了钛平面靶发射的X射线光谱, 实验结果表明它的光谱分辨率能达到0.001 nm.     

夸克胶子等离子体中的次带头阶得拜屏蔽质量

采用实时有限温度下的QCD,考虑到胶子的衰减率计算了QGP中次领头阶得拜屏蔽质量的贡献,克服了通常计算中的红外发散的困难,且不必引入非微扰的磁屏蔽质量作红外截断.指出了所得结果的正定性和规范无关性并与格点模拟的结果进行了比较.     

On the instability of ionospheric plasma originated by charge separations in the troposphere. The «UFO» phenomenon mechanism

Summary The troposphere is the seat of powerful processes which originate separation of electric charges. Thunder clouds give rise to a huge vertical separation of charges. But also known is a different electrification mechanism activated by wind, which allows for horizontal separation of charges. In favourable conditions, when charges are displaced at long distances, image charges appear in the ionspheric plasma and an upward electric field is originated which makes the ionosphere boundary unstable. If this occurs, recombination of displaced charges involves ionosphere conductivity and gives rise to a downward electron stream ejected from the bottom of the ionosphere. It may produce a peculiar airglow phenomenon, which consists of the emission of light in a narrow region lying at stratospheric or mesospheric altitudes. This outcome of the electrification process just mentioned shows a close connection with a special class of ?UFO? sightings, that is, those referred to by J. Hynek as ?nocturnal light? and which consist of bright specks of light moving in the night sky.