ULF/ELF ionospheric electric field and plasma perturbations related to Chile earthquakes

ULF/ELF electric field perturbations in the ionosphere have been widely observed by the satellites. In this paper, we develop a method of Logarithm Electric Field Intensity (LEFI) to automatically distinguish this kind of disturbances based on the spectrum intensity and its damping exponent with frequency in electromagnetic signals. This method is applied to DEMETER data processing around Chile earthquakes with magnitude larger than 6.0. It is found that 2/3 earthquakes have shown obvious ULF/ELF electric field perturbations in this region. The temporal and spatial distributions of electron density and temperature were compared with that of electric field, which proved the existence of irregularities above epicentral area. Finally, the coupling mechanism of earthquake-ionosphere is discussed based on multi-parameter analysis.     

The links between atmospheric vorticity,radiation belt electrons,and the solar wind

The links between winter storm intensity and solar wind variations associated with Heliospheric Current Sheet (HCS) crossings are shown to be present in 1997 through 2002 data without the necessity of high stratospheric aerosol loading.     

Comparison of the transport codes HZETRN,HETC and FLUKA for a solar particle event

The protection of astronauts and instrumentation from galactic cosmic rays and solar particle events is one of the primary constraints associated with mission planning in low earth orbit or deep space. To help satisfy this constraint, several computational tools have been developed to analyze the effectiveness of various shielding materials and structures exposed to space radiation. These tools are now being carefully scrutinized through a systematic effort of verification, validation, and uncertainty quantification. In this benchmark study, the deterministic transport code HZETRN is compared to the Monte Carlo transport codes HETC-HEDS and FLUKA for a 30 g/cm² water target protected by a 20 g/cm² aluminum shield exposed to a parameterization of the February 1956 solar particle event. Neutron and proton fluences as well as dose and dose equivalent are compared at various depths in the water target. The regions of agreement and disagreement between the three codes are quantified and discussed, and recommendations for future work are given.     

8cm汞离子推进器样机用小孔空心阴极设计

对小孔空心阴极内部放电物理过程作了描述。根据8cm 汞离子推进器与阴极相关的设计参数,计算了阴极内部压强、粒子密度、初始电子能量平均交换自由程等参量,因而设计出阴极发射体、阴极顶小孔等主要尺寸。复核了阴极发射电流。对阴极热平衡、加热器工作参量作了计算,并与实验结果进行了比较。根据阴极在推进器中工作方式,对阴极结构设计进行了描述,包括材料选择和等离子体喷涂工艺制造。给出了长期阴极热模拟实验结果。     

低纬100—200km间电子数密度的变化

利用光化平衡模式计算了低纬100—200km间白天电子数密度的变化。求得E-F₁谷区的谷深,谷宽、谷高的变化特征。获得如下结果:a.太阳活动明显影响电子数密度随高度及太阳天顶角的变化,发现太阳活动指数与电子数密度间不仅存在正相关,而且存在负相关;b.太阳活动明显影响E-F₁谷区的形态。在一定太阳活动条件下,对同一太阳赤纬和地理纬度,谷深、谷宽与太阳天顶角的关系难以用一简单函数来表示;c.太阳耀斑、地磁活动对该区电子密度有明显影响;d.在讨论100—200km间电子密度时不能忽略O+（2P）和NO的光电离率。      

赤道异常峰区电离层的某些特点

由于赤道异常北峰覆盖我国整个南部地带,因此对峰区电离层特征的研究就成为掌握中国电离层特点的关键之一。本文试图对以下六个问题作些介绍和评述:1.逐日起伏和子夜前极大;2.峰位置的移动;3.赤道异常的经度效应;4.不均匀结构引起的强闪烁和快速法拉第衰落;5.顶部电离层的离化突起和中性赤道异常;6.粒子沉降的双峰分布.      

一氧化氮对电离层电子密度的影响

本文利用电离层电子密度的理论计算模式,研究了一氧化氮对中、低纬度100-200km间电子密度的影响,发现电子密度与一氧化氮密度间存在着正、负相关。正相关,只有当这一光电离成为一氧化氮离子的主要生成源时才出现。      

太阳X射线暴在地球大气中传输的Monte Carlo模拟

应用MonteCarlo方法对太阳X射线暴(1-8?及0.5-4?)与地球大气相互作用过程进行跟踪模拟,得到了X射线暴在电离层D层产生的电子产生率,并计算了由此产生的宇宙噪声吸收值。结果与作者在南极观测得到的X射线暴期间宇宙噪声吸收值符合较好.      

卫星用粒子探测系统

设计了一个卫星用电子和质子探测系统,电子和质子能量范围各为0.5～4MeV 和5～60MeV。系统具有质量轻、功耗低及可靠性高特点。     

准一维传热下冷面绝热边界材料对隔热试验结果的影响

为评估冷面绝热边界对试验结果的影响,在充分验证测控系统可控性和试验方法稳定性的基础上,分别以柔性隔热毡、刚性隔热瓦和纳米隔热材料为冷面绝热边界,对陶瓷纤维刚性隔热材料进行500℃、3 000s的石英灯热辐射考核试验,并利用迭代绝热边界当量热导率的方法对试验结果进行了模拟计算和分析。结果表明,以柔性隔热毡为冷面绝热边界时隔热材料的冷面温度最高,刚性隔热瓦和纳米隔热材料为冷面绝热边界时则冷面温度较低且相近,3者间最大相对偏差高达19.0%。模拟计算证实由冷面绝热边界材料引起的接触热阻对试验结果起到了决定性作用,而不简单地取决于绝热边界材料的隔热性能。