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1.
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The distribution of the thermal effects of the ion thruster plume are essential for estimating the influence of the thruster plume, improving the layout of the spacecraft, and for the thermal shielding of critical sensitive components. In order to obtain the heat flow distribution in the plume of the LIPS-200 xenon ion thruster, an experimental study of the thermal effects of the plume has been conducted in this work, with a total heat flow sensor and a radiant heat flow sensor over an axial distance of 0.5–0.9 m and a thruster angle of 0°–60°. Combined with a Faraday probe and a retarding potential analyzer, the thermal accommodation coefficient of the sensor surface in the plume is available. The results of the experiment show that the xenon ion thruster plume heat flow is mainly concentrated within a range of 15°. The total and radial heat flow of the plume downstream of the thruster gradually decreases along the axial and radial directions, with the corresponding values of 11.78 kW m−2 and 0.3 kW m−2 for the axial 0.5 m position, respectively. At the same position, the radiation heat flow accounts for a very small part of the total heat flow, approximately 3%–5%. The thermal accommodation factor is 0.72–0.99 over the measured region. Furthermore, the PIC and DSMC methods based on the Maxwell thermal accommodation coefficient model (EX-PWS) show a maximum error of 28.6% between simulation and experiment for LIPS-200 ion thruster plume heat flow, which, on the one hand, provides an experimental basis for studying the interaction between the ion thruster and the spacecraft, and on the other hand provides optimization of the ion thruster plume simulation model.  相似文献   

2.
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A 2D hybrid-PIC simulation model is proposed to investigate the beam extraction phenomena ofthe ion thruster. In which the electrons of the plasma sheath upstream the accelerator grid areassumed as particles while the downstream are fluid for improving the calculation efficiency. Theion transparency, plasma sheath formation, ion beam extraction characteristic of a two- andthree-grid system have been compared in detail in this paper. From the comparison of theappearing time of the under-perveance phenomena in the two- and three-grid system, itillustrated that the two grid system has the wider operation range of the plasma densities than thethree-grid one.  相似文献   

3.
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In order to ascertain the key factors affecting the lifetime of the triple grids in the LIPS-300 ion thruster,the thermal deformation,upstream ion density and component lifetime of the grids are simulated with finite element analysis,fluid simulation and charged-particle tracing simulation methods on the basis of a 1500 h short lifetime test.The key factor affecting the lifetime of the triple grids in the LIPS-300 ion thruster is obtained and analyzed through the test results.The results show that ion sputtering erosion of the grids in 5 kW operation mode is greater than in the case of 3 kW.In 5 kW mode,the decelerator grid shows the most serious corrosion,the accelerator grid shows moderate corrosion,and the screen grid shows the least amount of corrosion.With the serious corrosion of the grids in 5 kW operation mode,the intercept current of the acceleration and deceleration grids increases substantially.Meanwhile,the cold gap between the accelerator grid and the screen grid decreases from 1 mm to 0.7 mm,while the cold gap between the accelerator grid and the decelerator grid increases from 1 mm to 1.25 mm after 1500 h of thruster operation.At equilibrium temperature with 5 k W power,the finite element method(FEM)simulation results show that the hot gap between the screen grid and the accelerator grid reduces to 0.2 mm.Accordingly,the hot gap between the accelerator grid and the decelerator grid increases to 1.5 mm.According to the fluid method,the plasma density simulated in most regions of the discharge chamber is 1?×?10~(18)-8?×?10~(18)m~(-3).The upstream plasma density of the screen grid is in the range 6?×?10~(17)-6?×?10~(18)m~(-3)and displays a parabolic characteristic.The charged particle tracing simulation method results show that the ion beam current without the thermal deformation of triple grids has optimal perveance status.The ion sputtering rates of the accelerator grid hole and the decelerator hole are 5.5?×?10~(-14)kg s~(-1)and 4.28?×?10~(-14)kg s~(-1),respectively,while after the thermal deformation of the triple grids,the ion beam current has over-perveance status.The ion sputtering rates of the accelerator grid hole and the decelerator hole are 1.41?×?10~(-13)kg s~(-1)and 4.1?×?10~(-13)kg s~(-1),respectively.The anode current is a key factor for the triple grid lifetime in situations where the structural strength of the grids does not change with temperature variation.The average sputtering rates of the accelerator grid and the decelerator grid,which were measured during the 1500 h lifetime test in5 k W operating conditions,are 2.2?×?10~(-13)kg s~(-1)and 7.3?×?10~(-13)kg s~(-1),respectively.These results are in accordance with the simulation,and the error comes mainly from the calculation distribution of the upstream plasma density of the grids.  相似文献   

4.
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In view of the high cost caused by the 1:1 lifetime verification test of ion thrusters, the lifetime acceleration test should be considered. This work uses the PIC-MCC (Particle-in-Cell Monte-Carlo Collision) method to analyze the five failure factors that lead to the failure of the accelerator grid of a 30 cm diameter ion thruster under the working mode of 5 kW. Meanwhile, the acceleration stress levels corresponding to different failure factors are obtained. The results show that background pressure has the highest stress level on the grid's erosion. The accelerator grid aperture's mass sputtering rate under the rated vacuum degree (1 × 10−4 Pa) of 5 kW work mode is 8.78 times that of the baseline vacuum degree (1 × 10−6 Pa), and the mass sputtering rate under worse vacuum degree (5 × 10−3 Pa) is 5.08 times that of 1 × 10−4 Pa. Under the influence of the other four failure factors, namely, the voltage of the accelerator grid, upstream plasma density, the screen grid voltage and mass utilization efficiency, the mass sputtering rates of the accelerator grid hole are 2.32, 2.67, 1.98 and 2.51 times those of the accelerator grid hole under baseline condition, respectively. The ion sputtering results of two 30 cm diameter ion thrusters (both installed with new grids assembly) after working for 1000 h show that the mass sputtering rate of the accelerator grid hole under vacuum conditions of 5 × 10−3 Pa is 4.54 times that under the condition of 1 × 10−4 Pa, and the comparison error between simulation results and test results of acceleration stress is about 10%. In the subsequent ion thruster lifetime verification, the working vacuum degree can be adjusted according to the acceleration stress level of background pressure, so as to shorten the test time and reduce the test cost.  相似文献   

5.
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To address the future application requirements of carbon-based material grids for ion thrusters characterized by high thrust, elevated specific impulse, and extended operational life, research was conducted using the LIPS-100 ion thruster developed by the Lanzhou Institute of Physics. This study focused on small-diameter configurations of carbon-carbon composite material grids. Successful development was achieved for both a 10 cm split carbon-carbon planar grid and an integrated carbon-carbon convex grid component. Performance variations among different configurations were investigated through extensive performance tests across the wide-range from 1 to 25 mN, as well as 200 h lifespan assessments under typical conditions at 20 mN. The results indicate that the two configurations of the carbon-carbon grid can achieve stable operation across the broad range of 1–20 mN, with beam current fluctuations ranging from 368 to 379 mA and accel grid current fluctuations between 1.58 and 1.81 mA. Furthermore, the key performance parameters of these grids were comparable to those of the traditional molybdenum grids. Under conditions of high thrust and power, the carbon-carbon grid demonstrated a significant reduction in the intercepted current at the accel grid. In comparison to the split carbon-carbon planar grid, the weight of the integrated carbon-carbon convex composite grid was reduced by 17.5%, the anode voltage decreased by approximately 2.4%–8.6%, and the cathode keeper voltage was reduced by approximately 3.5%–12.4%. It can be concluded that the integrated carbon-carbon convex grid offers distinct advantages in terms of hot-state structural stability, suppression of grid etching rates, and enhancement of thruster discharge efficiency.  相似文献   

6.
We have successfully developed a new method to reduce the amount of carbon buildup on thin cluster (less than 3.5 μg/cm2) carbon stripper foils by heating them with infrared radiation during beam bombardment. We studied the carbon buildup and the foil temperature on foil lifetime using a 2.0 ± 0.5 μA beam of 3.2-MeV Ne+ ions. It was found that the carbon buildup begins to rapidly suppress at 460 °C; further, at a foil temperature higher than approximately 820 °C, the initial foil thickness did not change until the foil ruptured. We also found that the carbon buildup shortens the lifetime of stripper foils.The foils treated by the newly developed present method could withstand the maximum and average total beam charges of 530 mC/cm2 and 340 mC/cm2, respectively, which are approximately 18 and 11 times larger than the values for the best commercially available foils and approximately 3 and 2 times greater than the values for the cluster foils that are not treated by this method.  相似文献   

7.
研制了一台用于加速器驱动次临界系统 (ADS)的强流电子回旋共振离子源。在 30keV能量下 ,引出的氢离子最大束流达到 1 0 0mA ,质子比好于 85 % ,引出束流密度最高可达 34 0mA/cm2 。初步测定的发射度约为 0 1 1πmm·mrad。已通过了 1 0 0h的连续运行考验。  相似文献   

8.
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The grid structure has significant effects on the discharge characteristics of an ion thruster. The discharge performances of a 30 cm diameter ion thruster with flat, convex and concave grids are studied. The analysis results show that the discharge chamber with a convex grid has a larger 'magnetic-field free area' than the others, and the parallelism of the magnetic-field isopotential lines and anode is generally the same in the three models. Plasma densities of the three structures at the grid outlet are in the range of 3.1 × 1016–6.9 × 1017 m−3. Along the thruster axis direction, the electron temperature in the chamber with the convex and concave grids is in the range of 3.3–3.5 eV, while that with a flat grid is lower, in the range of 3.1–3.5 eV. In addition, the convex and the concave grids have better uniform distribution of electron temperature. Moreover, the collision frequency ratios show that the axial degree of ionization of the three models is the highest, and the flat grid has the highest discharge efficiency, followed by the convex grid and the concave grid is the least efficient. The test and simulation results of the 30 cm diameter ion thruster with the convex grid show that the measurement and calculation results are 3.67 A and 3.44 A, respectively, and the error above mainly comes from the ignorance of the doubly charged ions and parameter settings in the model. The comparison error between the simulation and measurement of beam current density is mainly caused by the actual thermal deformation of the grids during the discharge process, which leads to the change in electric potential distribution and variation of the focusing characteristics of the grids. Upon consideration of discharge performance and the thermal grid gap variation, it can be concluded that the flat and concave grids are more suitable for small-diameter ion thrusters, while the convex grid is a more reasonable choice for the higher-power and larger-diameter thrusters.  相似文献   

9.
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Plasma in the discharge channel of a pulsed plasma thruster (PPT) with flared electrodes is simulated by a self-developed two-dimensional code. The fully particle-in-cell method with Monte Carlo collision is employed to model the particle movement and collisions and investigate the plasma properties and acceleration process. Temporal and spatial variations of the electron density distribution and the ion velocity between electrodes are calculated and analyzed in detail. The computational results of the electron number density, which is in the order of 1023 m−3, show good agreements with experimental results of a PPT named ADD SIMP-LEX. The ion velocity distributions along the center line of the channel lead to a comprehensive understanding of ions accelerated by electromagnetic field. The electron distributions of PPT with discharge voltages varying from 1300 to 2000 V are compared. The diffusion of electrons presents strong dependency on discharge voltage and implies higher degree of ionization for higher voltage.  相似文献   

10.
黄华庆 《核技术》1987,10(11):46-47
日本在辐射加工方面仅次于美国,其电子束功率约占世界总功率15MW的四分之一。日新高压公司(NHV)在廿五年内共生产电子辐照用加速器九十多台,总功率达3.25MW,最高能量达3MeV,最大束流达200mA,单机功率可达200kW,已形成系列产品,年生产能力为~400kW。  相似文献   

11.
介绍了一台能量2.5MeV、流强40mA、功率100kW的电子辐照加速器系统的屏蔽设计。实际测量结果表明:屏蔽外的辐射水平低于国家标准规定的限值,设计是合理的。  相似文献   

12.
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In a 2.45 GHz electron cyclotron resonance(ECR) ion thruster powered with rod antenna under a cross magnetic field, abnormal behaviours such as sudden drop of ion beam current(Ib) and larger increasing-rate of Ibin the high microwave power(Pw) discharges at high gas flow rates were observed. A differential method was proposed to reveal the changes in the radial profiles of gray values extracted from the end-view discharge images. The increasing-rate of Ibwith respect to Pwwas used to evaluate efficiencies of ion production and transport. Analyses indicate that discharges are dominantly sustained by ordinary wave via electron heating in the electron plasma resonance layer that can shift along the rod-antenna, and extraordinary wave can only ignite a discharge in the ECR layer in the low gas flow rate regime. In terms of the confinement region defined by the magnetic field lines intercepting with the screen grid, the confinement region of the optimized 2.45 GHz cross magnetic field takes the shape of hourglass, enabling the high increasing-rate of I_b with respect to P_w in high power discharges at high gas flow rates.Correlated with the accompanied bright boundary layer appearing in the differentiated image, the sudden drop of I_b in the low gas flow rate regime is attributed to the discharge ignited by the enhanced extraordinary wave in the ECR layer neighbouring the narrowest confinement region,where the produced ions can promptly enter the loss region.  相似文献   

13.
高能电子单粒子效应模拟实验研究   总被引:1,自引:0,他引:1  
本文基于2 MeV自屏蔽电子加速器和10 MeV电子直线加速器,开展了电子单粒子效应实验研究,并分析了其机理。在保持入射电子能量不变的情况下,在±20%范围内改变器件的工作电压进行了单粒子翻转实验。实验结果表明:45 nm SRAM(额定工作电压1.5 V)芯片在电子直线加速器产生的高能电子照射下能产生明显的单粒子翻转,单粒子翻转截面随入射电子能量的变化趋势与文献数据相符合;电子引起的单粒子翻转截面随器件工作电压的变化趋势与理论预期一致,即工作电压越小,单粒子翻转临界电荷越小,翻转截面也越高。  相似文献   

14.
Single ion microbeam is the most advanced technology which can emit a single ion for precise localization. A single-ion microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering (LIBB), Chinese Academy of Sciences (CAS), with a spatial resolutions of about 5 μm. Based on CAS-LIBB microbeam, three key elements affecting the quality of the system are assessed: the size of beam spot, the energy range and the counting accuracy of implanting ions. Various contributions to the ion beam stability, including the ion source, the terminal voltage of electrostatic accelerator and the components in beam pipeline, are discussed. Analysis shows that the improvement of terminal voltage stability is the most important issue for future optimization of CAS-LIBB facility. Some preliminary investigations and project aimed at optimization and development are proposed as well.  相似文献   

15.
In order to investigate the effects of secondary electrons, which are emitted from the wall, on the performance of a thruster, a one-dimensional fluid model of the plasma sheath in double walls is applied to study the characteristics of a magnetized sheath. The effects of secondary electron emission (SEE) coefficients and trapping coefficients, as well as magnetic field, on the structure of the plasma sheath are investigated. The results show that sheath potential and wall potential rise with the increment of SEE coefficient and trapping coefficient which results in a reduced sheath thickness. In addition, magnetic field strength will influence the sheath potential distributions.  相似文献   

16.
重离子加速器束运线数据库系统设计优化   总被引:1,自引:0,他引:1  
描述了兰州重离子加速器冷却储存环(HIRFL-CSR)束运线电源参数数据库系统的设计优化。依托HIFEL-CSR的主数据库系统Oracle,设计了电源电流的读取界面,实现电源的实时监控,建立了新的电源参数数据库分系统,并实现了Oracle数据库系统和Access数据库系统的数据互存,建立了方便的参数打印、查询界面。  相似文献   

17.
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In order to achieve a better understanding of plume characteristics of LIPS-300 ion thruster, the beam current density, ion energy and electron number density of LIPS-300 ion thruster plume are studied with an Advanced Plasma Diagnostics System(APDS) which allows for simultaneous in situ measurements of various properties characterizing ion thruster, such as plasma density, plasma potential, plasma temperature and ion beam current densities, ion energy distribution and so on. The results show that the beam current density distribution has a double‘wing' shape. The high energy ions were found in small scan angle, while low energy ions were found in greater scan angle. Electron number density has a similar shape with the beam current density distribution.  相似文献   

18.
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To reveal the argon plasma characteristics within the entire region of an electron cyclotron resonance(ECR) ion source, the plasma parameters were diagnosed using a bended Langmuir probe with the filament axis perpendicular to the diagnosing plane. Experiments indicate that,with a gas volume flow rate and incident microwave power of 4 sccm and 8.8 W, respectively,the gas was ionized to form plasma with a luminous ring. When the incident microwave power was above 27 W, the luminous ring was converted to a bright column, the dark area near its axis was narrowed, and the microwave power absorbing efficiency was increased. This indicates that there was a mode transition phenomenon in this ECR ion source when the microwave power increased. The diagnosis shows that, at an incident microwave power of 17.4 W, the diagnosed electron temperature and ion density were below 8 eV and 3?×?10~(17) m~(-3), respectively, while at incident microwave power levels of 30 W and 40 W, the maximum electron temperature and ion density were above 11 eV and 6.8?×?10~(17) m~(-3), respectively. Confined by magnetic mirrors, the higher density plasma region had a bow shape, which coincided with the magnetic field lines but deviated from the ECR layer.  相似文献   

19.
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Beam flatness is an important parameter that determines the performance and the lifetime of a gridded ion thruster.To improve the beam flatness of the 30 cm (LIPS-300) ion thruster,variable aperture ion optics that adapts to the decreasing ion density as the radius increases is proposed.It is the ion optics that the screen grid surface is divided into several zones,where the aperture diameter in each zone is determined by the ion density and the electron temperature upstream of the screen grid.The beam current density in the central area is artificially reduced.A particle in cell-Monte Carlo collision model is applied in this work to investigating the effect of variable aperture on the perveance and the maximum beam current per aperture by simulating the extraction,focusing and acceleration processes of ions.Taking into account the engineering implementability,the screen grid surface is divided into four zones.The hole diameter in each zone is decreased from 1.95 mm to 1.8 mm,1.9 mm,1.8 mm and 1.7 mm,respectively.The simulation results show that the maximum ion density in the center area of grid is decreased by 10.6% and 6.99%,while it is increased by 6.49% and 22.3% in the edge region,respectively.The beam flatness of the variable aperture ion optics is improved from 0.69 to 0.88.The erosion rate is decreased by 31.9%,but the total beam current is also decreased by 7.15%.The simulation results can provide a valuable reference of the development of the ion thruster.  相似文献   

20.
A three-dimensional particle simulation of ion thruster optics with charge-exchange collision was developed in this study. The simulation code was based on tracking ions using the particle-in-cell method, and the Monte Carlo technique was used to model the charge-exchange collision. Simulations were performed for a 20 cm ion thruster optics. The results were compared with the corresponding experimental data from a test of the ion thruster optics for a duration of 800 hours. The Depth-From-Focus (DFF) method was used to measure the erosion depth of the downstream surface of the accelerator grid. The predicted erosion depth of the accelerator grid was consistent reasonably with the corresponding experimental data. The simulation results showed that the accelerator grid would be burned through after 1333 hours.  相似文献   

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