负径向电场对带电粒子俘获率影响的数值模拟

本文采用数值方法求解Grad-Shafranov方程反演EAST典型长脉冲放电实验(炮号33068)的平衡位形和磁场分布，进而结合粒子在托卡马克电磁场中的运动方程，模拟氘离子在负径向电场存在时的运动轨迹，并统计不同负径向电场下的氘离子俘获率。结果表明：随负径向电场的增大，氘离子轨迹由扩张通行轨迹向外翻香蕉轨迹再向内翻香蕉轨迹，最后向压缩通行轨迹演变；氘离子俘获率随负径向电场的增大而减小，氘离子初始速度越小，其变化越大。     

The influence of inner material with different average thermal conductivity on the performance of whole insulation system for liquid hydrogen on orbit storage

At present, several composite insulation systems were proposed that can be used for passive insulation systems, including foam-variable density multilayer insulation (VDMLI), aerogel-VDMLI and hollow glass microspheres (HGMs)-VDMLI. The passive insulation systems with different inner material (IM) showed different performances. However, the relationship between the average thermal conductivity of IM and the insulation performance of the whole system has rarely been investigated. It is of great significance for efficient configuration and matching of the passive insulation system. In this paper, a series of average thermal conductivity of IM were assumed to predict the insulation performance of the whole system at 20 K–300 K and high vacuum. In order to further illustrate the relationship between IM and MLI/VDMLI, the foam was replaced by the HGMs as 5 mm a unit forming a series of HGMs-foam-MLI/VDMLI insulation systems. The performance of the systems was investigated. After the foam was completely replaced by the HGMs, the performance of MLI and VDMLI systems was improved 33% and 13%, respectively. Moreover, each mode of heat transfer including solid conduction, radiation, and gas conduction for foam-MLI/VDMLI and HGMs-MLI/VDMLI insulation systems were calculated and analyzed.     

Self-consistent kinetic theory with nonlinear wave-particle resonances

We have developed, based on the oscillating-center transformation, a general theoretical approach for self-consistent plasma dynamics including, explicitly, effects of nonlinear(higherorder) wave-particle resonances. A specific example is then given for low-frequency responses of trapped particles in axisymmetric tokamaks. Possible applications to transport as well as nonlinear wave growth/damping are also briefly discussed.     

Toward the Optimized Spintronic Response of Sn‐Doped IrO2 Thin Films

Amorphous and polycrystalline Sn‐doped IrO₂ thin films, Ir_1‐xSn_xO₂, are grown for the first time. Their electrical response and strength of the spin–orbit coupling are studied in order to better understand and tailor its performance as spin current detector material. These experiments prove that the resistivity of IrO₂ can be tuned over several orders of magnitude by controlling the doping content in both the amorphous and the polycrystalline state. In addition, growing amorphous samples increase the resistivity, thus improving the spin current to charge current conversion. As far as the spin–orbit coupling is concerned, the system not only remains in a strong spin–orbit coupling regime but it seems to undergo a slight enhancement in the amorphous state as well as in the Sn‐doped samples.     

Precise Orbit Determination for the FY-3C Satellite Using Onboard BDS and GPS Observations from 2013, 2015, and 2017

Using the FengYun-3C (FY-3C) onboard BeiDou Navigation Satellite System (BDS) and Global Positioning System (GPS) data from 2013 to 2017, this study investigates the performance and contribution of BDS to precise orbit determination (POD) for a low-Earth orbit (LEO). The overlap comparison result indicates that code bias correction of BDS can improve the POD accuracy by 12.4%. The multi-year averaged one-dimensional (1D) root mean square (RMS) of the overlapping orbit differences (OODs) for the GPS-only solution is 2.0, 1.7, and 1.5 cm, respectively, during the 2013, 2015, and 2017 periods. The 1D RMS for the BDS-only solution is 150.9, 115.0, and 47.4 cm, respectively, during the 2013, 2015, and 2017 periods, which is much worse than the GPS-only solution due to the regional system of BDS and the few BDS channels of the FY-3C receiver. For the BDS and GPS combined solution (also known as the GC combined solution), the averaged 1D RMS is 2.5, 2.3, and 1.6 cm, respectively, in 2013, 2015, and 2017, while the GC combined POD presents a significant accuracy improvement after the exclusion of geostationary Earth orbit (GEO) satellites. The main reason for the improvement seen after this exclusion is the unfavorable satellite tracking geometry and poor orbit accuracy of GEO satellites. The accuracy of BDS-only and GC combined solutions have gradually improved from 2013 to 2017, thanks to improvements in the accuracy of International GNSS Service (IGS) orbit and clock products in recent years, especially the availability of a high-frequency satellite clock product (30 s sampling interval) since 2015. Moreover, the GC POD (without GEO) was able to achieve slightly better accuracy than the GPS-only POD in 2017, indicating that the fusion of BDS and GPS observations can improve the accuracy of LEO POD. GC combined POD can significantly improve the reliability of LEO POD, simply due to system redundancy. An increased contribution of BDS to LEO POD can be expected with the launch of more BDS satellites and with further improvements in the accuracy of BDS satellite products in the near future.     

羧基修饰石墨烯吸附SF6分解组分的DFT计算

为研制高灵敏度SF6气体分解组分检测传感器,利用基于第一性原理的密度泛函理论(DFT)方法,采用分子模拟软件对SF6主要放电分解组分(SO2,SOF2,SO2F2,CF4)在羧基修饰石墨烯表面的吸附特性进行了模拟计算,从微观角度研究了羧基修饰石墨烯检测SF6气体放电分解组分的气敏机理。理论计算了单分子吸附过程中表征吸附性能特征参量的吸附能、吸附距离、净电荷转移量、分子前线轨道以及态密度。结果表明:羧基的修饰能够有效提高石墨烯的吸附性能,且羧基石墨烯效果更好,对4种分子吸附效果强弱依次为SO2>SOF2>SO2F2>CF4,其中SO2在羧基石墨表面发生较为强烈的化学吸附效应。     

近地卫星陨落期地球反照系数估计

为了研究地球反照的可见光对太阳电池阵电流在卫星陨落期间的影响程度,进行阵电流的地球反照系数估计。以运行在300km高度、降交点地方时约10:30AM的某太阳同步轨道近地卫星陨落为例,在讨论卫星轨道半长轴、倾角、光照角、降交点地方时等参数漂移的基础上,重点分析卫星太阳电池阵电流和温度的变化,并对电流进行正弦曲线拟合,进而建立地球反照系数的估计模型,最后用卫星陨落期间的遥测数据进行检验。结果表明,卫星自300km轨道高度向100km轨道高度陨落期间,地球反照系数先由0.21逐渐变大,最大值接近0.40,后又逐渐变小至0.20附近;对估计值的二次曲线拟合结果表明,在轨道高度210~270km这一区间,地球反照对于太阳电池阵的作用最强,对应的地球反照系数极大值约为0.28,作用最强的中心区域可能在250km轨道高度附近。估计结果可应用于在轨航天器长期管理的遥测诊断、能源估计与预测、器件健康状态评估以及可见光载荷应用等方面。     

基于响应时间约束的敏捷轨道设计方法

结合快响卫星在实际任务中的应用背景，研究了响应时间约束中的敏捷轨道设计方法。首先，根据快速响应卫星的发射点和目标点的位置关系，结合快速响应时间约束，得出了响应时间与轨道高度的不等式关系；其次，针对常见的圆形轨道，根据球面三角形公式，构建了敏捷轨道轨道周期、轨道倾角、升交点赤经的解析设计方法；最后，结合STK软件的典型任务仿真，分别设计了当圈响应与第3圈响应的两类敏捷轨道，使卫星分别在入轨10 min与200 min时星下点通过目标区域，验证了方法的可行性、易操作性和实用性。