Top Read Articles

    Published in last 1 year |  In last 2 years |  In last 3 years |  All
    Please wait a minute...
    For Selected: Toggle Thumbnails
    Verification on electromagnetic vector modulation of plasma flow generated in helicon plasma thruster#br#
    DING Liang, ZHENG Huiqi, PENG Yuchuan, REN Qiongying, ZHAO Hua
    Chinese Space Science and Technology    2020, 40 (4): 38-43.   DOI: 10.16708/j.cnki.1000-758X.2020.0043
    Abstract443)      PDF(pc) (10374KB)(181)      
    The electromagnetic vector modulation of electrical thruster′s flow is based on magnetic field reforming which leads to the orientation altering of plasma flow. To verify the electromagnetic vector modulation of electrical thruster, the theoretical simulation and experiments were carried out for the helicon plasma thruster (HPT). The magnetic field can be altered with electromagnetic vector modulation coils illustrated in theoretical simulation results. The plasma flow is deflected as the magnetic field is adjusted as shown in experimental results. Plasma density fluctuates according to an accessional magnetic field generated periodically. The plasma flow changes its orientation with 60 degrees at most with a modulated frequency which reaches 15Hz. The electromagnetic vector modulation for helicon plasma thruster is verified feasible.
    Related Articles | Metrics
    Parameter selection and control of field emission electric thrusters
    LIU Zijian, SHEN Yan, GENG Jinyue, LIU Xuhui, QIN Yu
    Chinese Space Science and Technology    2020, 40 (4): 1-10.   DOI: 10.16708/j.cnki.1000-758X.2020.0039
    Abstract401)      PDF(pc) (5166KB)(320)      
    Field emission electric thrusters have different working modes, and can produce either droplets or ions. The thrust parameters change widely due to different charge to mass ratio of the charged particles.For different space applications, different types of field emission electric thrusters need to be designed to achieve the corresponding thrust parameters. The emission process of the thrusters and the selection and control method of the thrust parameters were discussed. The basic working principle of field emission electric thrusters and each working mode were discussed. The calculation results show that different emission modes can be achieved with different propellants, followed by the conclusion that the thrust parameters are controlled by the propellants′ species, extract voltage and propellant flow rate, etc. Design and experiment results of an ionic liquid electro spray thruster show that the thrust and specific impulse produced by the thruster can be modified by changing the applied voltage. The thrust and specific impulse can reach 16~10μN and 154~978s respectively.
    Related Articles | Metrics
    Research on CEI phase delay resolving method for BDS GEO satellite
    CHEN Shaowu, WANG Jingwen, HUANG Lei, XU Dezhen
    Chinese Space Science and Technology    2020, 40 (6): 123-130.   DOI: 10.16708/j.cnki.1000-758X.2020.0079
    Abstract399)      PDF(pc) (3537KB)(279)      
    Connected element interferometry (CEI) is a precision angular measurement technology widely used in the orbit determination of MEO satellites, GEO satellites, lunar probes and deep space probes. A new measurement mode was proposed based on the characteristics of CEI. The carrier and ranging signals in coherent ranging mode were used in CEI. A CEI system was established and used to observe BDS (BeiDou navigation satellite system) GEO satellite. Group delay and phase delay were calculated by using all these signals. Group delay and phase delay results of the BDS GEO satellite were estimated by using the theoretical delay values calculated by precision ephemeris. The results show that the means of the residual of group delay and phase delay is 0.47ns and 0.08ns, and that the standard deviation (3σ) of the residual of group delay and phase delay is 4.2ns and 0.13ns. The feasibility of the phase delay calculation of CEI in coherent ranging mode is verified. This paper can provide reference for precision orbit determination of co-location GEO satellites, lunar probes and deep space probes.
    Related Articles | Metrics
    High specific impulse Hall thruster startup characteristics
    CHEN Jie, KANG Xiaolu, ZHAO Zhen, CHENG Jiabing, LIANG Wei
    Chinese Space Science and Technology    2020, 40 (4): 22-28.   DOI: 10.16708/j.cnki.1000-758X.2020.0041
    Abstract359)      PDF(pc) (4663KB)(244)      
    High specific impulse Hall thrusters have been valued from the early stage of the development of Hall thrusters, but there are few studies on parameter comparison, current changes and oscillation characteristics related to engineering applications. The performance and startup characteristics of HET80HP high specific impulse Hall thruster were given by measuring the thrust, current variation and oscillation of the thruster under different working conditions. The research results show that HET80HP high specific impulse Hall thruster has better performance than the traditional Hall thruster under the conditions of large flow rate and high discharge voltage. During cold start, there is a current spike in the discharge current under normal magnetic field conditions, and the current takes a long time to achieve relative stability. The variation of current during the hot start of different magnetic field configurations indicates that the presence of current spikes is mainly related to the magnetic field configuration and has no obvious relationship with the startup  temperature. In addition, by comparing the difference in thruster specific impulse and average frequency under different magnetic fields, it can be seen that the average frequency of lowfrequency oscillation of thruster can better reflect the magnitude of thruster specific impulse.
    Related Articles | Metrics
    Numerical study of electromagnetic acceleration mechanism for pulsed plasma thruster
    YANG Sanxiang, LIU Chao, WANG Shangmin, FENG Jie, CHEN Juanjuan, WU Chenchen, JIA Yanhui, GUO Ning, GENG Hai
    Chinese Space Science and Technology    2020, 40 (4): 11-21.   DOI: 10.16708/j.cnki.1000-758X.2020.0040
    Abstract343)      PDF(pc) (12440KB)(219)      
    In order to get a clear understanding of electromagnetic acceleration mechanism for pulsed plasma thrusters, and offer a theoretical foundation for the performance optimization and minification of the thruster,numerical simulation of the pulsed plasma thruster characteristic is necessarily to be researched. In this paper, a onedimensional integrated circuit model that includes the capacitance, inductance, electrodes and plasma is used to numerically study pulsed plasma thrusters. The electromagnetic acceleration mechanism of pulsed plasma thrusters is systematically investigated by varying the initial discharge voltage and separation distance of the electrodes. The results show that the thrust, specific impulse, impulse bit of pulsed plasma thrusters, and temperature and density of plasma increase with initial discharge voltage. Similarly, the thrust and specific impulse of thrusters also increase with the separation distance of electrodes. However, the igniting difficulty of thruster increases since the resistance between electrodes increases with the electrodes spacing. Therefore, there is an optimal value of distance between electrodes of the pulsed plasma thruster. 
    Related Articles | Metrics
    GEO satellite communication link budgets calculation and analysis
    XU Ting, LAN Hai, ZHANG Hongjiang
    Chinese Space Science and Technology    2020, 40 (3): 83-92.   DOI: 10.16708/j.cnki.1000-758X.2020.0035
    Accepted: 20 January 2020

    Abstract330)      PDF(pc) (3338KB)(258)      
    As an important technology, satellite-ground link budget calculation is the theoretical basis of satellite communication system designing which directly decides the link availability. As there are many factors which may affect the satellite link, any unreasonable factor in the design would make the whole satelliteground link unavailable and leads to a big loss. Moreover, there is no ideal satellite link situation unless overlooking some factors, which is also a difficulty during the link budget calculation. Based on the international common calculating method, GEO satellite link was analyzed thoroughly, separating the whole link into uplink and downlink. Then a practical example was analyzed and calculated according to the project experience in LAOSAT Company. At last, different reasonable designing methods in terms of different link configurations were obtained, which could be the references to link calculation and analysis of GEO satellite communication.
    Related Articles | Metrics
    System design and key technolongies of the GF-7 satellite
    CAO Haiyi, ZHANG Xinwei, ZHAO Chenguang, XU Chi, MO Fan, DAI Jun
    Chinese Space Science and Technology    2020, 40 (5): 1-9.   DOI: 10.16708/j.cnki.1000-758X.2020.0052
    Abstract318)      PDF(pc) (5941KB)(295)      
    GF-7 satellite is the first 1∶10000 scale stereoscopic surveying and mapping satellite independently developed in China, and an important part of the national high resolution earth observation system. The satellite is based on the active and passive combined surveying and mapping system of “two-line array surveying and mapping + laser altimetry” and forms a series of key technologies and innovation points, such as highprecision internal/external element stability design, highprecision attitude stability control, the first X-band adaptive high-rate data transmission system, and onboard intelligent satellite management system. The capability of large scale stereoscopic mapping with little or no control points was realized. The system design of the satellite was described, and the technical innovation points were summarized such as observation system, high-precision load, attitude control, digital data transmission, intelligent satellite service, etc. The preliminary evaluation was carried out through the test results of satellites in orbit, and the satellites can meet the requirements of the 1∶10000 surveying and mapping mission.
    Related Articles | Metrics
    Ballistic coefficient estimation method based on TLE and application analysis
    ZHANG Wei, CUI Wen, ZHANG Yuwei, LIU Xing, ZHU Jun
    Chinese Space Science and Technology    2020, 40 (3): 107-113.   DOI: 10.16708/j.cnki.1000-758X.2020.0038
    Accepted: 20 January 2020

    Abstract303)      PDF(pc) (3008KB)(153)      
    In order to meet the requirements of research which use two line element (TLE) as data source, ballistic coefficient estimation methods based on the variation in mean semimajor axis derived from TLE were studied. A direct estimation method based on two TLEs was introduced, and the influence of the TLE interval on the ballistic coefficient result accuracy was analyzed. In order to reduce the influence of outliers, an iterative estimation method based on multiple TLEs was proposed. Comparative analysis was made for these two methods. The results show that these two methods have their own advantages and disadvantages. The ballistic coefficient results estimated by the iterative method have higher stability and are less affected by the TLE accuracy. Due to the shorter data interval, the estimation results using the direct method respond more accurately to the short-term orbital variation characteristics, and this method is recommended to be used in the last phase of re-entry.
    Related Articles | Metrics
    Ionospheric VTEC fusion based on BP neural network technology
    GUO Chengjun, PANG Guoqiang
    Chinese Space Science and Technology    2020, 40 (4): 78-83.   DOI: 10.16708/j.cnki.1000-758X.2020.0048
    Abstract290)      PDF(pc) (3366KB)(98)      
    With the continuous development of ionospheric detection technology, there are more ionospheric observation data. Using only a single observation datum will cause the problem of low accuracy of ionospheric inversion. In order to improve the inversion accuracy of the ionosphere, the BP neural network technology is used to effectively fuse the vertical total electron content (VTEC) data of ground-based inversion and international reference ionosphere (IRI) model inversion. Ionospheric inversion experiments were performed in temperate regions [35°(N)--45°(N),60°(E)--80°(E)\]. The results show that the data fusion based on BP neural network technology and ground-based inversion can both achieve high accuracy of ionospheric VTEC. The data fusion method based on BP neural network has higher ionospheric inversion accuracy than ground-based inversion, so data fusion based on BP neural network technology can improve the ionospheric inversion accuracy.
    Related Articles | Metrics
    Design of satellite-borne microwave photonic mixer based on DDMZM
    HUI Jinxin, ZHAO Ying, DENG Xiangke, ZHENG Feiteng, SUN Shufeng
    Chinese Space Science and Technology    2020, 40 (3): 36-42.   DOI: 10.16708/j.cnki.1000.758X.2020.0030
    Accepted: 19 February 2020

    Abstract289)      PDF(pc) (2308KB)(118)      
    Due to the influence of distributed parameters on microwave components, there is certain frequency selectivity, and it is difficult to achieve the broadband and multi-band compatible frequency conversion system, which can no longer meet the needs of the high-throughput satellite communication payload. Microwave photonics technology provides the possibility of realizing high-throughput satellite communication needs with its advantages of large bandwidth and no frequency selectivity. Based on dual-drive Mach-Zehnder modulator (DDMZM), the solution of the frequency conversion unit of the satellite communication system was explored. Through theoretical analysis of the link model, the software VPI was used to simulate and optimize the link to find the best offset point of the DDMZM. The experimental results show that when the modulator is biased at the minimum point, the frequency conversion efficiency is high, and it has certain carrier suppression function, which can achieve broadband, multi-band and anti-interference performance,and is superior to microwave frequency conversion performance.
    Related Articles | Metrics
    Effect of temperature on magnetic field configuration of magnetically shielded Hall thruster#br#
    ZHAO Zhen, CHENG Jiabing, KANG Xiaolu
    Chinese Space Science and Technology    2020, 40 (4): 29-37.   DOI: 10.16708/j.cnki.1000-758X.2020.0042
    Abstract288)      PDF(pc) (6885KB)(94)      
    Magnetostatic simulation in room temperature condition is mostly applied for Hall thruster design and verified with measurement in non-working state. Severer thermal issues will be addressed for larger power Hall thrusters and result in magnetic deviation under high temperature. In order to study thermal influence, 10kW Hall thruster thermomagnetic coupling simulation was carried out. Comparing both results, discrepancy of magnetic radial component on Br centerline near anode was larger than that in exit. Magnetic shielding obtained in room temperature simulation was deviated in thermal state with non-compliance between field and wall up to 13%, through wall shape recorrection, magnetic shielding was restored with noncompliance below 4.8%. Reasonable design reduced thermal loads. Simulation showed that the maximal circuit temperature was less than 500℃, lower than 0.78 times of Curie temperature, which would not lead to sharp drop in magnetic performance, but thermal impact on magnetic configuration needs to be considered in magnetic shielding simulation.
    Related Articles | Metrics
    Study on maneuver methods of satellites constellation with continual small-thrust propulsion
    YANG Shengqing, WANG Yu, WANG Danna, LIN Rongfeng, DU Yaoke, ZHONG Chao
    Chinese Space Science and Technology    2020, 40 (4): 69-77.   DOI: 10.16708/j.cnki.1000-758X.2020.0047
    Abstract286)      PDF(pc) (4819KB)(139)      
    Based on the orbit dynamic characteristics, orbit maneuver methods of satellites constellation with continual small-thrust propulsion are studied in this paper. Because of the huge scales of constellations, orbit maneuver of constellation in near-earth orbit can hardly be managed by traditional method as trajectory planning. Orbit insertion for constellation configuration is considered as a relative semimajor axis control problem in timedelay maneuver sequence. Meanwhile, offset control of inclination is considered for drift of right ascension of ascending node(RAAN) during arisingorbit maneuver. For consideration of orbit discarded problem, a unitedcontrol for combination of semimajor axis and eccentricity is designed for a rapid orbit decay with energy-saving. Because of the curveeffect for continual smallthrust propulsion, curvilinear integral of orbit control should be investigated for all the strategy optimizations.
    Related Articles | Metrics
    Research on passive intermodulation based on broadband modulation signal
    LI Yanping, HUANG Hao, HE Jie
    Chinese Space Science and Technology    2020, 40 (3): 13-18.   DOI: 10.16708/j.cnki.1000.758X.2020.0027
    Accepted: 17 February 2020

    Abstract267)      PDF(pc) (1204KB)(160)      
    With the extensive use of transmitter-recevier sharing and digital modulation (BPSK,QPSK) technologies in satellite communication, there are insufficient verification problems in the original continuous wave (CW) and passive inter modulation (PIM) test system. In this paper, a broadband digital signal PIM test method was designed by using the channel power to test PIM. The test results show that digital modulation PIM values of both BPSK and QPSK signals are higher than the CW carriers by 2~9 dB. Considering the operational reliability of the satellite, the digital modulation working mode was adopted to improve the original test system and the new test is closer to the pracical work, which improves the reliability of ground verification.
    Related Articles | Metrics
    Research on policybased remote sensing satellite control method
    XU Yudong, HAO Jigang, LIU Boyang
    Chinese Space Science and Technology    2020, 40 (4): 97-106.   DOI: 10.16708/j.cnki.1000-758X.2020.0050
    Abstract267)      PDF(pc) (5263KB)(147)      
    For the problems of complex operation and many manual interventions caused by the tight coupling of business applications and underlying scheduling in remote sensing satellite management and control, a policy-based remote sensing satellite control method is proposed. On the basis of constructing the policy management model, the closed loop structure of hierarchical control is adopted to complete the closed loop of satellite control. A domain management method for satellite clusters is proposed, and a policy deployment mechanism is set up. The implementation method of policy-based remote sensing satellite management and control is discussed in detail. Simulations are performed on a typical case of the search mission for a lost ship, and it is verified that the method can complete eventbased closedloop control of heterogeneous satellite clusters. The policybased management method can effectively reduce the complexity of remote sensing satellite management and control services, and realize the automatic control of remote sensing satellite clusters.
    Related Articles | Metrics
    Influence of 3D regular surface morphology on secondary electron emission
    ZHANG Na, CUI Wanzhao, CAO Meng, WANG Rui, HU Tiancun
    Chinese Space Science and Technology    2020, 40 (3): 1-7.   DOI: 10.16708/j.cnki.1000.758X.2020.0025
    Accepted: 04 March 2020

    Abstract253)      PDF(pc) (3603KB)(138)      
    It has been applied in many fields to customize specific surface morphology to control secondary electron emission of materials.The regular surface morphology can easily reveal the influence of the suppression and the influence mechanism on the secondary electron emission. Meanwhile, photolithography, plasma etching and other processes can better achieve the specific design of regular morphology. Therefore, custom regular morphology is often used in the initial research stage of multipactor or in the process of principle experimental verification. Taking the threedimensional cylindrical hole as an example, multi-generation Monte Carlo method which considers multiple interactions between electrons and complex surface morphology was used to systematically study the influence of regular morphology parameters such as depthwidth ratio and duty cycle ratio on secondary electron yield (SEY), secondary electron spectrum (SES) and emission angle distribution. It was found that the larger the depthwidth ratio of regular morphology is, the wider the SES broadening, the stronger the selectivity of the morphology to emission angle, and the better restraint effect of SEY, but the restraint effect is not indefinite. When the morphology does not overlap, SEY can also be effectively reduced by increasing the duty cycle ratio. However, due to the relatively small proportion of emitted electrons of the cylindrical hole compared with flat surface, the SES and the emission angle distribution is close to flat surface. The secondary electron emission properties of regular morphology obtained in the paper provide a reference for the comprehensive evaluation of its influence on multipactor effect.
    Related Articles | Metrics
    Research on trusted fullproxy homomorphic transmission  mechanism for satellite communication#br#
    DING Yi, SHEN Wei, LI Jie, CHENG Zijing, JIN Jun, SUN Jianing
    Chinese Space Science and Technology    2020, 40 (4): 84-96.   DOI: 10.16708/j.cnki.1000-758X.2020.0049
    Abstract246)      PDF(pc) (6604KB)(105)      
    Satellite communication and its applications have become an important part in current social life. In order to ensure the secure transmission of satellite communication data, privacy protection of information, and to sovle the problem of dependency on the receiving side, a set of full proxy reencryption transmission model (FPRM) was proposed based on typical application scenarios of the transmission of low orbit constellation meteorological data. It was instantiated according to the satellite communication architecture to design a trusted proxy homomorphic transmission system. Computable ciphertext and full proxy transmission have been implemented by adding security of system communication and privacy protection to the mechanism. It is of great practical significance and values to integrate satellite, commercial data centers and Internet resources to reduce costs and improve resource utilization. Finally, it proves that the performance and data scalability of this model are feasible through experiments.
    Related Articles | Metrics
    A yaw angle adjustment strategy during IGSO satellite orbit maintaining#br#
    CUI Zhen, JI Ye, LIU Weijie, WANG Chunyuan, FENG Jiajia
    Chinese Space Science and Technology    2020, 40 (4): 107-112.   DOI: 10.16708/j.cnki.1000-758X.2020.0051
    Abstract244)      PDF(pc) (2318KB)(108)      
    Aiming at the problem of maintaining the orbit of the inclined geosynchronous orbit (IGSO) satellite, a yaw angle adjustment strategy under various working conditions was proposed. The purpose was to reduce the yaw angle adjustment range and shorten the yaw angle adjustment time, and to reduce the impact of the orbit maintenance process on the continuity of satellite services. The law of yaw angle motion and the effect of the right ascension of ascending node on the yaw angle were analyzed. On this basis, the influences of the right ascension of ascending node, the range of the solar altitude angle, the orbit control time, and the position of the intersection on the yaw angle adjustment strategy were analyzed. The method of adjusting the yaw angle and the choice of thruster when the satellite orbit is being maintained were given. For satellites whose intersections are located in China, the range of yaw angle adjustment does not exceed 45°. This method can be applied to the  management of satellite orbit maintenance.
    Related Articles | Metrics
    Design of L-band space based wideband low noise amplifier chip
    ZHAO Bochao, XU Hui, YIN Pan, HE Juan, ZHANG Dawei, XU Xin
    Chinese Space Science and Technology    2020, 40 (3): 19-24.   DOI: 10.16708/j.cnki.1000.758X.2020.0028
    Accepted: 04 March 2020

    Abstract243)      PDF(pc) (4040KB)(162)      
    An L-band monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) used in satellite microwave receiver was developed with 0.25μm GaAs pseudomorphic high electron mobility transistor (pHEMT) technology. The current reuse topology structure was used to achieve lower current and the precious satellite power resource was saved. The two-stage negative feedback was applied to increase stability and gain flatness, and then satellite communication quality was improved. The constant current source bias stabilized the working conditions where current was slightly influenced by the processes. The test results show that the working current is below 35mA, from 0.9GHz to 1.8GHz, the gain is higher than 33dB with gain flatness less than 0.5dB, the noise figure is below 0.6dB, and the size of the LNA chip is 2.0mm×1.3mm. The circuit can meet the requirement of high performance and miniaturization in space application.
    Related Articles | Metrics
    Sliding mode control based on fuzzy neural network for variable structure spacecraft
    WANG Ran, ZHOU Zhicheng, QU Guangji, CHEN Yujun
    Chinese Space Science and Technology    2020, 40 (3): 56-63.   DOI: 10.16708/j.cnki.1000-758X.2020.0032
    Accepted: 15 March 2020

    Abstract232)      PDF(pc) (3275KB)(172)      
    Variable structure spacecraft is an important development direction of astronautics. The mass distribution of the spacecraft will change significantly during the configuration variation, and this will generate new problems of dynamic modeling and controller design. To solve these problems, the hybrid coordinate method and Lagrange equation were used to build the dynamic model of the spacecraft, and changing rule of the dynamical parameters was approximated by several typical working conditions. Sliding mode controller was designed to control the attitude during the variation of the spacecraft. To improve the adjustment of the controller, fuzzy neural network(FNN) was designed to adjust the parameters of the controller adaptively. The radial-based function (RBF) neural network was designed to approximate dynamic model, and thus the relationship between the control torque and attitude variation was obtained, which was used to optimize the FNN. The attitude of the variable structure spacecraft during the structure variation with no control, sliding mode control and fuzzy neural network was acquired in simulation. The results verify the effectiveness of the fuzzy neural network adaptive sliding mode controller, and comparisons were made to verify the good properties of the proposed controller.
    Related Articles | Metrics
    Research on performance of TWF composites for space antenna
    LI Yichen, SONG Yanping, HU Fei
    Chinese Space Science and Technology    2020, 40 (3): 25-35.   DOI: 10.16708/j.cnki.1000.758X.2020.0029
    Accepted: 05 March 2020

    Abstract229)      PDF(pc) (6291KB)(96)      
    Using a carbon fiber triaxial woven fabric (TWF) as a reinforcing material and compounding it with a suitable flexible matrix material, a carbon fiber three-directional woven composite shell film structure is formed,featuring both flexibility and rigidity. As a satellite antenna reflector, it is a new type of high precision deployable antenna implementation.  The mechanical properties of silicone matrix TWF composites were studied. Using the composite mesoscopic method, the material properties of the homogeneous fiber bundle were obtained from the material properties of the fiber and the matrix. Then, considering the fiber bundle interlacing (undulation fluctuation), a unit cell finite element model composed of the fiber bundle was established. Homogenization analysis of the unit cell finite element model was carried out, applying periodic boundary conditions, and finally obtaining equivalent homogeneous material properties. In order to meet the high performance requirements of antenna reflectors, the influence of carbon fiber type and fiber volume content on the equivalent performance of unit cell was analyzed. The mechanical properties of the material were studied, which provides a theoretical basis for its application to large deployable highprecision antenna reflectors in the future.
    Related Articles | Metrics