Table of Content

    15 November 2017, Volume 37 Issue 6 Previous Issue    Next Issue
    Statistical Properties of Solar Proton Events during Solar Cycle 23 and 24
    BAI Tienan, LE Guiming, ZHAO Haofeng
    2017, 37 (6):  649-658.  doi: 10.11728/cjss2017.06.649
    Abstract ( 869 )   PDF (1047KB) ( 6130 )   Save

    There were totally 128 Solar Proton Events (SPEs) from 1997 to 2016. Their peak flux ranges are from 10pfu to 99pfu, 100 to 999pfu, 1000 to 2999pfu and greater than 3000pfu, and the percentage is 55.15%, 27.94%, 9.56% and 7.35% respectively. The results show that SPEs with different peak flux have different asymmetry. The SPEs with peak flux ranged from 1000pfu to 2999pfu have the largest asymmetry, while those with peak flux greater than 3000pfu have smallest asymmetry. In Solar Cycle 23, the SPEs mainly occurred during the period from the first peak to the second peak and after the second peak of the smoothed monthly mean sunspot numbers. In Solar Cycle 24, the SPEs mainly occurred during the period before maximum of smoothed monthly mean sunspot numbers.

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    Relationship between Dynamic Pressure Pulse and Geomagnetic Sudden Commencement
    LI Yuxin, XIE Yanqiong
    2017, 37 (6):  659-666.  doi: 10.11728/cjss2017.06.659
    Abstract ( 684 )   PDF (1265KB) ( 3160 )   Save

    A deep understanding of the relationship between geomagnetic SC (Sudden Commencement) and DPP (Dynamic Pressure Pulse) is important for comprehensively understanding the response characteristics of geomagnetic field to interplanetary disturbance and improving the ability of SC prediction. In this paper, 363 SC events observed between 1994 and 2011 are the objectives. Firstly, whether there are corresponding DPP events associated with the SC events or not are determined by using automatic DPP recognition algorithm. Secondly, the characteristics of the DPP events and the SC events as well as their relationship statistically are analyzed. The results are as follows. 91% of the SC events are associated with the DPP events, and 53% of the SC events are associated with the shocks. The DPP events and the shocks are observed by WIND satellite. This result indicates that DPP is the main cause of SC. Most of the DPP events (70%) that cause the SC events are associated with large scale solar wind structures, such as Interplanetary Coronal Mass Ejections (ICME), Corotating Interaction Region (CIR) and complex projections aused by ICME and/or CIR. And the averaged dynamic pressure amplitude change of the DPP events is 3.9nPa. Strong DPP events account for 42% of all the events. There is an obvious relationship between the amplitude of the SC events and the absolute dynamic pressure change as well as the difference of the square root of the dynamic pressure of the DPP events, and the correlation coefficients are 0.79 and 0.82, respectively. The correlations between them are much stronger when the interplanetary magnetic field is southward. Although the duration, speed and amplitude of DPP have a certain influence on the duration of SC respectively, there is no obvious relationship between them. These results contribute to the prediction of SC based on DPP parameters.

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    Study of Multi-directional muon flux in geomagnetic storm prediction
    XUE Bingsen, CANG Zhongya, ZHANG Jilong
    2017, 37 (6):  667-674.  doi: 10.11728/cjss2017.06.667
    Abstract ( 755 )   PDF (1704KB) ( 790 )   Save

    By analyzing the characteristics of cosmic ray flux evolution, the approaching of CMEs could be identified, and the geomagnetic disturbance could be forecasted. The modulation of cosmic by CMEs could be derived by comparing the fluxes from different directions, and the parameters, such as Interplanetary Magnetic Field (IMF) and direction, could be derived. In this paper, data obtained by Nagoya muon telescope are used, and southward and eastward flux are chosen for investigation in detail. The results show that the evolutions of muon fluxes from the two directions share similar pattern before the strong geomagnetic storm, while there is a 2-hour phase delay between them. It is analyzed that the cosmic rays corresponding to the two directions went into and out the CME successively and the time difference is about 2 hours. The correlation coefficient and flux difference of the fluxes in eastern and southern, concluding the phase of the southern flux is moved backward two hours or not, are calculated respectively. As CMEs approaching, the correlation coefficient with southward phase change is significantly higher than that without phase change, and the flux difference with the southward phase change is much lower than that without phase change. However, the coefficient and the flux difference began to get close to each other when CMEs arrive at the Earth. And the above parameters of phase changed disparity amplitude even exceeded the unchanged one. The characteristics are also found in the geomagnetic storms with Kp=9 from 2003 to 2005. The muon flux before the great geomagnetic storm on December 14, 2006 is analyzed, and the study found that it is coincident with the above characteristics. Therefore, directional muon detection possesses a unique ability to remote sensing CMEs propagation through the difference of the flux evolution from different directions.

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    Empirical reconstruction of flux transfer events at the magnetopause
    LI Zhaoyu, CHEN Tao
    2017, 37 (6):  675-689.  doi: 10.11728/cjss2017.06.675
    Abstract ( 663 )   PDF (4699KB) ( 2056 )   Save

    Flux Transfer Events (FTEs) observed at the Earth's magnetopause are generally believed to be products of transient and patchy magnetic reconnection processes, serving as linkage channels between solar wind and Earth's magnetosphere and therefore playing a crucial role in the exchange of mass, momentum, and energy between these two regions. Magnetic field reconstruction techniques are useful for better understanding FTE's formation and evolution and its interaction with surrounding environment. Traditional techniques such as Grad-Shafranov reconstruction and FTE model fitting methods, however, are confined to specific physical conditions. A new multi-point method applicable to two-dimensional FTEs in various physical condition is devised based on plane linear interpolation. The applications to two FTEs observed by THEMIS and Cluster show that the method can quickly and efficiently reconstruct the spatial distribution of the magnetic field structure, and will help to infer the magnetic field line configurations, understand the temporal variation of measured data and analyze the spatial distribution characteristic of plasma parameters relative to the magnetic field.

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    Statistical Modeling Research on the Magnetosheath Plasma Density
    CHEN Kaiwen, LAI Peng, ZHAO Kai, JIANG Yong
    2017, 37 (6):  690-701.  doi: 10.11728/cjss2017.06.690
    Abstract ( 699 )   PDF (3502KB) ( 716 )   Save

    By using the simulation data of the ideal MHD LFM model, the model of the mean plasma density of the magnetosheath from 03:00UT to 07:00UT on November 14, 2004 is established based on the Sliced Inverse Regression (SIR) and Local Polynomial Regression (LPR) method. The statistical relationship between the mean plasma density and the upstream solar wind parameters, the interplanetary magnetic field, and the geomagnetic disturbance indices are analyzed. The results show that the ionospheric disturbance intensity factor, the solar wind-magnetosphere coupling intensity factor, and the Sun-Earth coupling intensity factor are the three main factors which influence the plasma density of the magnetosheath. The up-flowing ions are the important source for magnetosphere circular current and magnetotail plasma during the recovery phase. The analyses show that, as modeling the process of space physics by the empirical regression method, the multi-collinearity problem usually leads to the poor accuracy of the model. However, the statistical models built by the non-parametric statistical method of SIP and LPR can efficiently solve the problems above.

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    Analysis of Low Latitude F Region Field-aligned Irregularity Events Observed with Hainan VHF Radar
    SHANG Sheping, SHI Jiankui, YAN Jingye, YANG Guotao, YAN Chunxiao, WANG Xiao, WU Qiongzhi
    2017, 37 (6):  702-709.  doi: 10.11728/cjss2017.06.702
    Abstract ( 732 )   PDF (2516KB) ( 750 )   Save

    Hainan VHF radar has the rapid scan observation capability of two-dimensional imaging of ionospheric irregularities, which is essential for investigating the generation and evolution of Field-Aligned Irregularities (FAI). In this study, the ionospheric irregularities observed by Hainan VHF radar on the night of Oct. 27, 2011 have been analyzed. The main results show that the observed irregularities can be divided into three stages. In the initial formation stage, the irregularities appear very weak and develop very slowly, which mainly expand upward and last for about 14 minutes. In the expansion and enhancement stage, the irregularities rapidly expand and develop both in upward and zonal directions, which last for about 14 minutes. The intensity of irregularities early increases rapidly and later slightly decreases. The spatial scale of irregularities exceeds more than 200km. In the stage of eastward drift and leaving, the intensity of irregularities further decreases, and the expansion area reaches the maximum. It mainly shows the eastward drift and last for nearly 30 minutes. This observation firstly gives the formation and development processes of ionospheric irregularities over the Hainan region, which seems to be quite different from that of other regions.

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    Simulation of Incoherent Scatter Radar Spectra Based on Inhomogeneous Distribution
    XU Bin, WANG Zhange, XU Zhengwen, WU Jian, XUE Kun
    2017, 37 (6):  710-716.  doi: 10.11728/cjss2017.06.710
    Abstract ( 705 )   PDF (1435KB) ( 667 )   Save

    Based on the theoretical hypothesis of ion inhomogeneous distribution during ionospheric heating, the model of non-equilibrium 3D velocity distribution of the ions with acoustic frequency exciting is built, and the calculation method of incoherent scatter spectra with arbitrary line of sight are presented. The effect of the amplitude modifying factor, particle component of acoustic frequency, the angle between radar beam and magnetic field direction, and temperature inhomogeneous on power spectra are analyzed. The results can perfectly explain amplitude enhancement of ion line that is more than an order of magnitude, and asymmetry phenomena when the ascending ion line is stronger than the down ion line. The study has great significance for plasma parameter inversion under the condition of strong disturbance heating of ionospheric.

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    Application of Carbon Dioxide Methanation in the Regenerative Loop Environmental Control and Life Support Systems of Manned Spacecraft
    SONG Pengfei, HOU Jianguo, WANG Xiulin, ZHANG Yu, YAO Huichao
    2017, 37 (6):  717-723.  doi: 10.11728/cjss2017.06.717
    Abstract ( 674 )   PDF (806KB) ( 667 )   Save

    Carbon dioxide (CO2) methanation (Sabatier reaction) is one of the key techniques of air quality management in the manned space Environmental Control and Life Support System (ECLSS). Meanwhile, the same carbon dioxide methanation technology is also used in coal chemical industry. The carbon dioxide methanation reaction mainly occurs at the last stage of coke oven gas methanation process and coal-to-substitute natural gas methanation process, using carbon dioxide methanation catalyst. Great progress has been made in China's industrial methanation technology in recent years. The technology for industrial high purity carbon dioxide maybe helpful for the research of Sabatier technology used in spacecraft. In view of the latest development of industrial methanation technology, the Sabatier reaction and the industrial carbon dioxide methanation technology are summarized and compared, from three aspects including CO2 methanation process, catalyst and reactor, and suggestions for the research of Sabatier technology in manned spacecraft are given.

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    Error Source Analysis of Atmospheric Occultation Sounding System
    HAN Ying, FU Yang, BAI Weihua, GONG Xiaoyan
    2017, 37 (6):  724-728.  doi: 10.11728/cjss2017.06.724
    Abstract ( 948 )   PDF (807KB) ( 686 )   Save

    The error sources that influence the precision of atmospheric retrieval parameters obtained by the atmospheric occultation sounding system are studied. Each error which contributed to the total variance of the product was analyzed in detail, such as the Doppler observation error, the antenna phase center changing error, multipath error, the satellite centroid change error, the GNSS satellite clock drift error, satellite attitude variety error and the velocity error of precise orbit determination. The main errors that must be accounted carefully are the Doppler observation error, the multipath error, the antenna phase center changing error and the satellite attitude variety error. Especially if the distance between the satellite centroid and the occultation receiving antenna phase center is larger than 0.5m, or the satellite attitude variety is larger than 0.01(°) ·s-1, the error will become unacceptable. According to the implementation feasibility, the total error allocation scheme can offer a reference for the system design of atmospheric occultation sounding system.

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    Research on the Calibration of Ion Drift Meter aboard CSES
    ZHENG Xiangzhi, ZHANG Aibing, GUAN Yibing, LIU Chao, TIAN Zheng, KONG Linggao, WANG Wenjing, DING Jianjing
    2017, 37 (6):  729-737.  doi: 10.11728/cjss2017.06.729
    Abstract ( 825 )   PDF (1262KB) ( 697 )   Save

    The scientific objective of Ion Drift Meter (IDM) is to measure ion drift velocity, which is perpendicular to the direction of the satellite flight on orbit. IDM calibration includes electronics calibration and plasma environment test. The measurement precision of velocity is validated through testing electronics noise. The velocity measurement range is calibrated by testing the current measurement range. The method and results of gain and temperature drift of electronics circuit testing are introduced. The plasma environment test of IDM has been carried out in INAF-IAPS plasma environment test instrument. The experimental results show that the detector has good performances and will contribute much to the space plasmas parameters monitoring.

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    Development of the Testing and Calibration Platform for Space Electron Radiation Environment Research Payloads
    ZHOU Ping, WANG Wenjing, JING Tao, ZHANG Aibing, GUO Panlin, SHENG Shugang, JING Yuhui, SUN Yueqiang, LIANG Jinbao, ZHU Guangwu, JI Wentao, MA Liyuan
    2017, 37 (6):  738-747.  doi: 10.11728/cjss2017.06.738
    Abstract ( 752 )   PDF (3974KB) ( 579 )   Save

    In order to test and calibrate the satellite payloads-electron detectors, the medium-and high-energy electron accelerators with extremely weak beam current to simulate the electron radiation environment of space have been built, including the experimental terminal which have a vacuum chamber and a vacuum rotation plate. This work focuses on the physical design and simulation of extremely weak, uniform, parallel electron beam of the medium-energy one, by using electron trajectory program Egun. The simulation results of electron trajectory in the initial focusing system, the accelerating tube and the twice beam broaden on different conditions including without grid, with ideal grid and with 1mm diameter aperture grid in the spherical electron gun are presented. Finally, the beam density, 105~109cm-2·s-1 within the ø 50mm target area, can be weakened by 8 orders of magnitude from the electron gun to the target area, and could satisfy the requirement of electron detectors testing and calibration experiment.

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    An Optimization Design Method for Thermal Control of Satellite Propulsion Subsystem
    ZHOU Yangeng, ZHOU Xiujuan, ZHANG Yu, ZHAO Jizhe, WU Zishuai, GUI Lijia, HU Xiaokang
    2017, 37 (6):  748-751.  doi: 10.11728/cjss2017.06.748
    Abstract ( 917 )   PDF (1656KB) ( 756 )   Save

    The conventional thermal control requirements of satellite propulsion subsystem are that the pipings and parts of hydrazine tank need tropical winding and multilayer coating. In this paper, an optimization design for thermal control of propulsion subsystem under a new type of propellant is proposed, in which the propulsion module controlled heat treatment measures are cancelled, the propulsion module outer plate is coated with multiplayer insulation components, and compensation heating for electromagnetic valve is adopted. Thermal balance testing and in-orbit validation are conducted for thermal control propulsion subsystem with optimized design. The results show that the level of propulsion subsystem temperatures and power requirements can meet the requirements of current range of domestic thermal control of satellites. Optimized design of the propulsion subsystem thermal control have the advantages of low power consumption, light weight and easiness of assembly. By combining with the satellite configuration, the subdivision operation can be achieved.

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    Design of Optical System for Off-axis Reflective Star Sensor Ground Calibration Equipment
    ZHU Haoran, LIU Yunqing, ZHANG Wenying
    2017, 37 (6):  752-759.  doi: 10.11728/cjss2017.06.752
    Abstract ( 754 )   PDF (2084KB) ( 682 )   Save

    Before the star sensor completes the attitude measurement task with the launch of the spacecraft, it must be calibrated on the ground. In order to meet the requirements of high precision star sensor calibration, according to the shortcomings of optical structure of conventional ground calibration equipment for large aperture, long focal length and wide spectrum requirements, an off-axis collimator was designed as a collimating optical system. The alignment method of the off-axis collimator was discussed, and the image quality was also evaluated. A set of lighting system is designed to precisely control the star point brightness. The LED array backlight is used as the light source, and the brightness of the light source is tested by an illumination meter. Experimental results show that seven consecutive magnitudes can be simulated, and the simulated error between neighboring magnitudes is less than 0.8%. The designed optical system can provide the ground calibration foundation for the development of deep space exploration star sensor.

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    A Light Source System of Multi-star Simulator with Adjustable Background and Controllable Magnitude
    SUN Gaofei, LIU Shi, ZHANG Guoyu, ZHANG Yu, LEI Jie, MA Yiyuan
    2017, 37 (6):  760-765.  doi: 10.11728/cjss2017.06.760
    Abstract ( 675 )   PDF (1163KB) ( 739 )   Save

    A light source of multi-star simulator capable of background adjustment and magnitude control has been designed. Two integrating spheres are employed as the star-point light source and the background light source respectively. A beam splitter prism has been designed to serve as the beam combiner for the star-point and the background light sources, and a mathematical model has been constructed respectively to compute the light flux of the two integrating spheres. A magnitude testing system and a background testing system have been created using low-light illuminometer, luminance meter, and testing instruments to measure the star-point magnitude and the background luminance of the multi-star simulator. The test results suggest that the star-point magnitude is adjustable from 0 to +5mv, with a simulation precision superior to ±0.026mv. The maximum background luminance is 3.8×105 cd·m-2, and the minimum background luminance is 6.4×10-2 cd·m-2. The designed light source system can meet the requirements for simulating the stellar map with a sky background.

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    Long-term Planning Algorithm for the HXMT Mission
    HUANG Yue, QU Jinlu, JIA Shumei, MA Xiang, SONG Liming, CHEN Li, ZHANG Wenzhao
    2017, 37 (6):  766-772.  doi: 10.11728/cjss2017.06.766
    Abstract ( 796 )   PDF (1419KB) ( 613 )   Save

    Hard X-ray Modulation Telescope (HXMT) satellite is China's first space X-ray astronomy satellite. The planning and scheduling of HXMT observations is a complex multi-objective optimization problem, and the optimization object is to maximize simultaneously the scientific return and the observation efficiency. By analyzing the characteristics of HXMT observations and all the important factors in the efficient scheduling of a celestial source, such as celestial constraints and the additional scientific constraints, the HXMT long-term planning model is established. The greedy algorithm and genetic algorithm are combined to solve the model. Simulation results show that the approach is effective in solving the HXMT long-term planning problem, based on the analysis of the first year observations of Suzaku Mission.

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