克里雅河流域平原区土地利用类型时空演化规律及驱动因素分析

为推动克里雅河流域土地资源的合理开发利用及绿洲湿地保护,在基于研究区30年土地覆被类型数据的基础上,分析区域土地利用类型的时空演化规律及影响因素。结果表明:近年来研究区耕地及建设用地呈增加趋势,林草地呈先减后增趋势,水域及未利用地呈减少趋势;各类型土地转变频繁,其中草地和未利用地面积转变最多,建设用地转变最少;2000年后区域生态环境有所改善,荒漠化进程变缓;流域各土地利用类型的转变均主要受区域经济社会发展及人口变化的影响。克里雅河流域在今后应持续加强生态保护与修复,提高用水效率,以期实现区域荒漠和绿洲平衡共存。

阿克苏河下游区灌溉入渗补给系数计算及影响因素分析

【目的】准确获取阿克苏河下游区灌溉入渗补给系数,对该区灌溉入渗补给系数的影响因素进行分析,为绿洲带高强度人工灌溉模式下地表水地下水转化机理研究,提高研究区地下水数值模拟精度提供基础。【方法】选取阿克苏下游区不同灌溉制度、包气带厚度、土壤结构下代表性点进行野外取样及室内灌溉试验,并结合Hydrus-1d进行包气带水流数值模拟,通过改变灌溉制度、包气带厚度,应用Hydrus-1d模型计算该土壤结构下的灌溉入渗补给系数变化。在模型计算结果的基础上,首先分析灌溉制度、包气带厚度与灌溉入渗补给系数的关系;其后重点利用模型计算结合数理统计的方法分析土壤结构中影响灌溉入渗补给系数的主要因素。【结果】研究区内滴灌条件下灌溉入渗补给系数的范围为0.320~0.474;畦灌条件下灌溉入渗补给系数的范围为0.408~0.561,即不同灌溉制度下灌溉入渗补给系数不同;而伴随包气带厚度增大,灌溉入渗补给系数也随之减小;土壤结构对灌溉入渗补给的主要影响因素为土壤渗透系数、土壤体积质量、土壤初始含水率。【结论】根据室内试验结合数值模型计算出不同灌溉制度下的灌溉入渗补给系数变化范围,得出灌溉入渗补给系数的影响因素为灌溉制度、包气带厚度和反映土壤结构的土壤渗透系数、土壤体积质量及土壤初始含水率,为干旱区下游区灌溉入渗补给系数选取及后续研究提供理论依据。

A One-Dimensional Hybrid Simulation of DC/RF Combined Driven Capacitive Plasma

We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions （IEDs） and ion angle distributions （IADs） on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.

喀什噶尔河流域平原区土地利用类型时空分布特征及趋势分析

以喀什噶尔河流域平原区近30年土地利用类型遥感解译数据为基础,应用多种方法从定性到定量对研究区土地利用类型时空分布规律及变化趋势进行分析。结果表明:近年来,平原区出现了耕地与建设用地扩增,天然林、草缩减及植树造林等现象共存;受外界及人为因素影响,不同土地利用类型在不同时段内呈现出不同的变化趋势,尤其是耕地向东南外扩明显;以耕地为例,平原区外扩耕地主要由草地及未利用地转变而来。流域水土资源的可持续利用及生态环境保护具有十分重要的现实意义。

Feature Profile Evolution During Etching of SiO_2 in Radio-Frequency or Direct-Current Plasmas

We have developed a plasma etching simulator to investigate the evolution of pattern profiles in SiO2 material under different plasma conditions. This model focuses on energy and angular dependent etching yield （physical sputtering in this paper）, neutral and ion angular distributions, and reflection of ions or neutrals on the surface of a photoresist or SiO2. The effect of positive charge accumulation on the surface of insulated mask or SiO2 is studied and the charge accumulation contributes to a deflection of ion trajectory. The wafer profile evolution has been simulated using a cellular-automata-like method under radio-frequency （RF） bias and direct-current （DC） bias, respectively. On the basis of the critical role of angular distribution of ions or neutrals, the wafer profile evolution has been simulated for different variances of angles. Observed microtrenching has been well reproduced in the simulator. The ratio of neutrals to ions has been considered and the result shows that because the neutrals are not accelerated by an electric field, their energy is much lower compared with ions, so they are easily reflected on the surface of SiO2, which makes the trench shallower.

南疆典型灌区土壤盐渍化参数空间变异性分析

为查明南疆典型灌区土壤含盐量参数的空间分布特征,运用数理统计及地统计学方法对灌区土壤含盐量空间分布特征进行分析。结论表明:研究区土壤含盐量参数空间变化较大;土壤含水率与pH易受到随机性因素影响,含盐量易受结构性及随机性因素共同影响;含水率及pH的空间分布杂乱,含盐量整体表现为南高北低;对比分析灌区土壤含盐量参数的平面及剖面空间分布状况,在一定程度上揭示了灌区人类活动等对土壤盐渍化参数空间分布及含量变化的影响规律。该结论对于进一步了解南疆典型灌区土壤水盐运移规律、盐渍化分区及治理具有重要的现实意义。

New Progress on Ion-plasma Interaction and the Developing Diagnostics Technology for HEDM at HIAF

Plasma as the fourth state of matter widely exists in universe and it is the essential state in the process of Initial Confinement Fusion sciences.Ion beam is a unique tool to understand some special properties of plasma itself form the aspect of kinetic interaction between ion and plasma surrounding.The energy loss of helium ions in a dense plasma relates to the self-heating process in a ICF capsule and the radiation protection by Van Allen Radiation Belt of Earth-self against the solar wind.It is a very interesting topic to carry out the series of experiments applying the ion beam and plasma target together in lab[1,2].

3-18 Research Activities Related to High Energy Density Physics

High energy density is generally defined as a state with energy content larger than 1011 J/m3,or equivalently with pressure higher than 1 Mbar.High energy density matter widely exists in the universe,like the cores of Jupiter,Sun and Earth,as well as inertial confinement fusion.The creation of high energy density state in the laboratory and the research on its properties are very important in astrophysics,planetary sciences,geophysics,inertial fusion sciences and so on.Related to high energy density physics,we carried out a series of research activities including simulation of the state of warm dense matter at HIAF,ion-plasma interaction,highly charged ions induced nanoscale defect on surface and X-ray emission,as well as developing a new multi-channel pyrometer and high energy electron radiography.

基于HIAF装置的高能量密度物理研究

高能量密度物理的研究对象是能量密度超过1011J/m3或压强超过100 GPa极端状态的物质,这种物质广泛存在于恒星和大质量行星内部,同时也短暂存在于核弹爆炸和惯性约束聚变等高功率加载过程中.高能量密度物理研究是科技强国在国防安全、天体物理及聚变科学技术等重大领域竞相追逐的前沿热点,也是国内外大型高功率激光装置、Z箍缩装置以及重离子加速装置的重要科学目标.本文将主要介绍基于强流重离子加速器装置(High Intensity heavy-ion Accelerator Facility,HIAF)的高能量密度物理研究.HIAF装置将可以提供极高功率的强流重离子束,单脉冲能量和功率将分别达到100 kJ和TW量级.如此高功率的离子束直接加热金、铅等固体材料,可以产生密度接近原固体密度、温度约10 eV、空间尺度mm–cm量级的状态均匀的高能量密度物质(能量密度达到1013J/m^(3)量级),为实验室研究高能量密度物质的产生、物态性质及其演化规律提供先进的研究平台.基于HIAF的高能量密度物理研究主要包括:(1)强流离子束驱动高能量密度物质的产生及其发展规律;(2)离子束在稠密物质或等离子体中的能量沉积与输运性质;(3)离子束驱动高能量密度物质关键诊断技术.本文还将重点介绍上述三个关键科学技术问题的研究现状和进展.

低温等离子体中的介质阻挡放电

介质阻挡放电(Dielectric Barrier Discharge,DBD)是一种常见的大气压开放环境下能产生非热平衡低温等离子体的放电方式。由于其放电结构中有绝缘介质层存在,因而能够有效地抑制局部火花或电弧的产生,从而产生大面积、高能量密度低温非平衡等离子体。DBD放电结构有很多种,最典型的是以针板电极、板板电极为代表的体放电以及能将等离子体引出到开放空间的射流发生器等。