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    25 February 2016, Volume 36 Issue 1 Previous Issue    Next Issue
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    Research on the principle of RF ion thruster without a neutralizer
    XIA Guang-Qing, XU Zong-Qi, WANG Peng, ZHU Yu, CHEN Mao-Lin
    2016, 36 (1):  1-8.  doi: 10.3780/j.issn.1000-758X.2016.0004
    Abstract ( 888 )   PDF (1879KB) ( 2054 )   Save
    In the wide application of electric thrusters, most of them accelerate positive ions to generate thrust, and need to install the neutralizer which can emit electrons to neutralize the positive ions. Otherwise it will cause the spacecraft self-charging, and the communication equipment and electronic devices will be damaged. Therefore, the neutralizer performance becomes  an important factor restricting the working state of the electric thrusters. In order to overcome the shortcoming, a kind of RF ion thruster without a neutralizer based on accelerating positive and negative ions alternately was introduced. The structural components and the propulsion principles were described. The generation of ion-ions and accelerating process of positive and negative ions were discussed. The key techniques including electronegative gas discharge characteristics and magnetic field filter the electrons efficiency, as well as the applied bias voltage way for grids in which the positive and negative ions could be accelerated alternately and periodically were pointed. The analysis results indicate this thruster has potential application prospect in the low orbit spacecraft and deep space probes.
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    Study on emission mechanism of ultrasonically electric propulsion
    ZHANG Yao-Bin, HANG Guan-Rong, DONG Lei, KANG Xiao-Ming, ZHAO Wan-Sheng, ZHANG Yan, KANG Xiao-Lu
    2016, 36 (1):  9-17.  doi: 10.3780/j.issn.1000-758X.2016.0005
    Abstract ( 941 )   PDF (4846KB) ( 1114 )   Save
    To improve the thrust of colloid thrusters by increasing the number of emitters, a novel electric propulsion method named ultrasonically electric propulsion (UEP) was proposed.The dense capillary standing waves produced by ultrasonic vibration are the emitters,so the number and density of emitters are improved fundamentally and relatively high thrust density appears.The emission mechanism of UEP was analyzed and the corresponding emission model was developed. Through theoretical analysis on the formation of capillary standing waves and the emission of the charged droplets, the relationship among the surface tension, inertial force and electrostatic force at the crests of standing waves was introduced. Furthermore, the radius of the standing wave crests and the diameter of the charged droplets were theoretically solved. The estimation equations of spray current, specific impulse and thrust were proposed. Based on the theoretical analysis, the influences of the electric filed strength, ultrasonic vibration frequency, ultrasonic vibration power and propellant on the performance of UEP were analyzed and experimentally verified.
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    Optimal design of orbital transfer with chemical-electric hybrid propulsion system based on a new Gauss pseudospectral method
    YANG Bo, CHEN Zi-Yun, WEN Zheng, MIAO Jun
    2016, 36 (1):  18-25.  doi: 10.3780/j.issn.1000-758X.2016.0006
    Abstract ( 930 )   PDF (3972KB) ( 1160 )   Save
    A kind of chemicalelectric hybrid mode propulsion system was proposed for the orbit transfer mission of GEO satellite. This propulsion system has a good application prospect and can fit much of the engineering demands,such as high-degree payloads and high-accuracy orbit insertion.The research on the optimization methods of the transfer orbit based on the hybrid mode propulsion system was carried out. A new Gauss pseudospectral method to solve the multi phase optimum control problem was proposed,which transformed the multiple nonlinear programming problems transformed by Gauss pseudospectral method to one by setting up the linkage of the breaking points. Two simulation examples indicate that this method can effectively solve the optimization problem of the multi-phase non-smooth orbit. It has the advantages of high operation efficiency, big convergence radius and high solving accuracy, and can conveniently and fast process the optimization design of the transfer orbit based on the hybrid mode propulsion system.
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    Low frequency oscillation characteristics in a cusped field thruster
    HU Jun-Feng, LIU Hui, LI Jian-Zhi, SUN Qiang-Qiang
    2016, 36 (1):  26-34.  doi: 10.3780/j.issn.1000-758X.2016.0007
    Abstract ( 953 )   PDF (2204KB) ( 855 )   Save
    The operation mode of the thruster is divided into high current mode and low current mode to study the low frequency oscillation characteristics in a cusped field thruster. The characteristics of low frequency oscillation were studied by changing working parameters and magnetic field configuration. The effects of the outer circuit on the low frequency oscillation were also studied. Results show that the operation mode of the cusped field thruster converted from high current mode into low current mode with the increase of discharge voltage under the condition of high mass flow. In comparison, the discharge current in high current mode has the characteristics of high amplitude and low frequency with vague plume. With the increasing of discharge voltage, the current oscillation amplitude increases and then decreases, while oscillation frequency increases along with the discharge voltage. However, the discharge current in low current mode has the characteristics of low amplitude and high frequency, and plume has two obvious bright lines. Current oscillation amplitude and  frequency increases with the increasing of discharge voltage. With the increasing of mass flow rate, discharge current oscillation amplitude and frequency tend to increase in different working conditions. Meanwhile, the resistance and inductance in the outer circuit can suppress low frequency oscillation, but the effect of capacitance on low  frequency  oscillation is not obvious.
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    Experiment to improve the performance of an ECR neutralizer
    LUO Li-Tao, YANG Juan, JIN Yi-Zhou, SUN Jun, HAN Fei
    2016, 36 (1):  35-42.  doi: 10.3780/j.issn.1000-758X.2016.0008
    Abstract ( 1001 )   PDF (2762KB) ( 795 )   Save
    The problem about domestic electron cyclotron resonance neutralizer is that electron beam can′t be extracted continuously at the variation of bias voltage.To overcome this, an experiment of neutralizer electron beam extraction was carried out to improve the performance through changing the antenna structure and adjusting the size of the electron extraction aperture. The experimental results show that the electron beam can be extracted continuously with the increasing  of the bias voltage. The propellant efficiency and electron energy loss for the improved neutralizer under the operation conditions are 1.659 8 and 126.3 W/A respectively,while 1.278 9 and 194.573 W/A respectively before neutralizer improvement. The plasma density within the neutralizer diagnosed by the Langmuir probe is in the range of 1.72×1017~12.1×1017 m-3.
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    Numerical simulation of the flow characteristics within the constrictor of an arcjet thruster
    WEI Fu-Zhi, HE Yan, GENG Jin-Yue
    2016, 36 (1):  43-50.  doi: 10.3780/j.issn.1000-758X.2016.0009
    Abstract ( 947 )   PDF (6270KB) ( 1034 )   Save
    The constrictor is a key part of arcjet thrusters, which has a significant effect on the performance and efficiency of the arcjet thruster.A modeling study was performed to investigate the plasma flow through the constrictor of medium power arcjet thrusters based on the local thermal equilibrium (LTE) assumption. The effects of the current, inlet pressure, constrictor dimensions and different propellants on the plasma flow characteristics, including the nonuniform flow characteristics, within the arcjet constrictor were studied. And the effects of the current, inlet pressure and constrictor dimensions on the performance and efficiency were further presented. The numerical results show that the hot arc region radius and length increase with the increase of the current; with the increase of the inlet pressure, the radius of hot arc region decreases but length increases;with the decrease of the constrictor radius, the hot arc region radius decreases while length increases; the hot arc region length increases and radius shows no significant changes with the increase of the constrictor length; and the hot arc region with hydrogen as the propellant is apparently smaller than those with nitrogen and argon as the propellant. It is also found that a small amount of the gas passes through the hot arc region where the gas is ionized, and most of the gas flows through the low temperature region near the wall. The Joule heating within the constrictor approximately accounts for 60 %-80 % of the total Joule heating within the arcjet thruster, mainly affected by the constrictor length.
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    Effect of pre-ionization on low frequency oscillation and wall corrosion in Hall thrusters
    QUAN Lu-Lu, XING Wei, LU Chang, GONG Ke-Yu, CAO Yong
    2016, 36 (1):  51-57.  doi: 10.3780/j.issn.1000-758X.2016.0010Hall
    Abstract ( 812 )   PDF (3400KB) ( 987 )   Save
    With the proposed of ATON-Hall thrusters,a series of studies were carried out based on pre-ionization phenomenon in buffer. However, the selection of pre-ionization rate is still inconclusive.Therefore, two-dimensional axisymmetric full particle PIC (Fully-kinetic Particle-In-Cell) simulations were carried out based on the real size of SPT-100 Hall thruster to simulate the discharge process in the discharge chamber. The relations between and among pre Ionization rate, low frequency oscillation in the discharge channel and wall corrosion of Hall thruster were mainly studied. The simulation results show that increasing the pre-ionization rate in the buffer chamber can effectively suppress low frequency oscillation, and improve the performance of the propeller. But at the same time, the increase of the energy of ion impacting on the channel surface aggrevates the corrosion of the surface, and shorten the propeller′s shorten service life.
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    Effects of azimuthal non-uniformity of neutrals on the discharge characteristic and performance of Hall thruster
    FAN Jin-Rui, DING Yong-Jie, SUN Guo-Shun, YU Da-Ren, WEI Li-Qiu
    2016, 36 (1):  58-62.  doi: 10.3780/j.issn.1000-758X.2016.0011
    Abstract ( 868 )   PDF (3530KB) ( 842 )   Save
    Researches show that the gas distributor of Hall thrusters with manufacture and installation error, or the vent holes plugged up by the sputtered particles would result in azimuthal non-uniformity of neutrals. The influences of the degree of azimuthal non-uniformity of neutrals on the discharge characteristic and performance of Hall thrusters were studied by plugging up the vent hole of gas distributor. Current characteristic,  ion current density distribution and overall performance were obtained by experiments. Results show that azimuthal non-uniformity of neutrals results in higher discharge current with the maximum of increments of 25 %, lower thruster efficiency, lower special impulse, and bigger oscillation.
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    Hybrid-PIC simulation of Hall thruster plume shield on GEO satellites
    LIU Hui, LUO Xiao-Ming, WEN Zheng, WANG Jue, YU Da-Ren
    2016, 36 (1):  63-69.  doi: 10.3780/j.issn.1000-758X.2016.0012
    Abstract ( 1118 )   PDF (7300KB) ( 567 )   Save
    The plume of the Hall thruster has negative effects on cover glasses of the solar panel which have high light transmission.Therefore, it is necessary to design some protective structures for solar array.Firstly, some related works were reviewed. Then, two different protection schemes were simulated using hybrid-PIC for a GEO satellite equipped with a SPT100. Finally, the advantages and disadvantages of the two schemes were analyzed and some valuable suggestions were proposed. The output power of solar array will be decreased if they are polluted.
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    Study on moment dumpling of electric propulsion satellite
    MA Xue, HAN Dong, TANG Liang
    2016, 36 (1):  70-76.  doi: 10.3780/j.issn.1000-758X.2016.0013
    Abstract ( 878 )   PDF (3521KB) ( 979 )   Save
    Moment dumpling of electric propulsion satellite can be established by pointing the thrust vectors slightly away from the center of mass. On the basis of this method, electric propulsion moment dumpling for both normal mode and failure mode was investigated. The analytic solution of optimal dumpling directions was given,and the question that whether the control arc should be considered was discussed. The simulation results show that proposed method can effectively perform the moment dumpling by electric thrusters.
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    Effects of discharge voltage and screen grid voltage on performance of ion thruster
    WANG Yu-Wei, REN Jun-Xue, JI Lin-Jie, TANG Hai-Bin
    2016, 36 (1):  77-84.  doi: 10.3780/j.issn.1000-758X.2016.0014
    Abstract ( 746 )   PDF (4336KB) ( 1151 )   Save
    The effects of discharge voltage and screen grid voltage changing to working performance of a 6 cm Kaufman ion thruster were studied by combination of experiments and numerical simulation. In these experiments, the argon was used as propellant for the ion thruster,and many groups of data were gathered. Furthermore, based on Goebel′s theory model,the effects of discharge voltage changing on beam current and propellant efficiency were simulated.And the particle in cell Monte-Carlo collide (PIC-MCC) theory was used to simulate the effects of screen voltage on beam current, propellant efficiency and acceleration grid current. Experiments and numerical simulation drew the same conclusions. When discharge voltage increases, ion beam current and propellant utilization efficiency tend to be stable after a corresponding increase. A similar beam electric current and propellant utilization efficiency changing pattern is observed when the screen grid voltage is increased,but acceleration grid voltage tends to be stable after a corresponding decrease. This study can provide a reference for increasing multimodes ion thrusters' performance.
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    Thermal design and optimization of LIPS-300 ion thruster in  geosynchronous orbit
    HU Guo-Jie, LI Jian, LIU Bai-Lin
    2016, 36 (1):  85-96.  doi: 10.3780/j.issn.1000-758X.2016.0015
    Abstract ( 1225 )   PDF (9287KB) ( 605 )   Save
    The Large heat dissipation of LIPS-300 ion thruster seriously affects its performance.Therefore, the thermal design and analysis of LIPS-300 ion thruster in geosynchronous orbit were carried out. The simulation results show that under the hightemperature working condition,the downstream harness, downstream and upstream anode, screen grid, and downstream magnet are the positions with the highest temperature,and the temperature of the downstream magnet exceeds the temperature upper limit. In order to decrease the temperature of the downstream magnet, two optimization design measures were presented and tried. The analysis results indicate that increasing heat radiation area is an effective optimization design measure while enhancing the inner heat exchange is noneffective.
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    A diagnostic scheme for electron density in μ-PPT plasma using H Stark broadening
    WANG Shang-Min, ZHANG Jia-Liang, ZHANG Tian-Ping, FENG Jie, ZHENG Mao-Fan, HUANG Yong-Jie
    2016, 36 (1):  94-102.  doi: 10.3780/j.issn.1000-758X.2016.0016
    Abstract ( 976 )   PDF (3229KB) ( 956 )   Save
    A method of electron density measurement    inside discharge channel of pulsed-plasma thruster (PPT) with higher accuracy was proposed,    based on Stark broadening spectrum analysis. By measuring the line profile and the full-width at half-maximum (FWHM) of C atom spectrum emitted by PPT plasma,the electron density can be calculated. But this requires adequate high electron density. If the electron density is lower than 1016 cm-3, the accuracy of diagnosis is dramatically decreased. Therefore, a tiny H tracer based on H atom spectrum of the line profile and the full-width at half-maximum was proposed to measure the electron density. Comparing with the conventional method, it can improve remarkably the accuracy of electron density measurement.
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    Space potential diagnostic study of ion thruster′s plume
    CAO Shuai, TANG Hai-Bin, ZHANG Zun, ZHANG Zhe
    2016, 36 (1):  103-112.  doi: 10.3780/j.issn.1000-758X.2016.0017
    Abstract ( 951 )   PDF (7035KB) ( 1031 )   Save
    The plume plasma potential distribution of ion thruster could deeply affect the normal work of the whole spacecraft and cause some extremely serious problems. In our experiments an emissive probe was used to measure the beam plasma potential of a 20 cm-ion thruster using Xe as propellants. Experiments were performed at axial distances from 250 mm to 900 mm downstream of the thruster′s exit plane and radial locations ranging from 0 to 450 mm. The emissive probe based on thermionic electron emission was made of 0.1 mm diameter tungsten filament with its heat current from 1.5 A to 2.5 A. The knee point of the emissive probe′s  I-V curve is clearer than that of the Langmuir probe, so the space potential distribution of our measurement results is more accurate. Emissive probe has been broadly used to diagnose plasma potential abroad, but lots of literatures indicate that there are still some divergences in the probe′s data processing methods. The probe′s working physical process of the probe was studied, and the effects of the emissive thermionic electron quantity on plasma potential diagnosis results were analyzed. Different processing methods of the probe′s  I-V curve were adopted and the advantages and disadvantages of each method were discussed. The reasons why measurement results deviate from the true plasma potential distribution were analyzed, which not only provide references for the structural reform of Emissive probe and the selection of heating current,but also give some suggestions for the plume simulation model and the improvement of thruster performance.
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    A theoretical method for xenon′s physical property used in electrical propulsion system
    CHEN Tao, LIU Guo-Xi, SONG Fei, WU Cong-Long
    2016, 36 (1):  113-119.  doi: 10.3780/j.issn.1000-758X.2016.0018
    Abstract ( 840 )   PDF (3824KB) ( 939 )   Save
    The possible operation temperature of propellant xenon in electrical propulsion system  is between 30 ℃  and 45 ℃, which covers the xenon′s critical temperature. At the critical temperature, xenon′s state is sensitive to the operating pressure and the ambient temperature. The propellant may exhibit different forms. These characteristics make the traditional equation of state ineffective to calculate the p-V-T relationship in the above temperature  range (max error may rise to 30 %). To solve this problem, a new calculation method based on the corresponding state principle was put forward for physical property estimation. The theoretical outcomes were compared with experiment data and available database. The results show that among the whole temperature and pressure range, the method is capable to predict the xenon′s physical property in gas, liquid, supercritical state with an error less than 0.5 %.
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