Grid Gap Variation of Ion Thruster During Startup in Orbit

Sun, Mengjia; Zheng, Yi; Geng, Hong

doi:10.1109/tps.2020.2965798

Cited by 8 publications

(7 citation statements)

References 18 publications

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“…Plasma density and electron temperature in the discharge chamber of the thruster with the convex grid have not been measured at present. Therefore, the accuracy of the calculated results of the convex grid discharge model is verified by the relationship between the ion beam current and plasma density in the upstream region of the grids, which is shown in equation (6). If the comparison error is small, it is considered that the calculation results of the discharge models with the flat and concave grids are also accurate, and the three models can reflect the effects of different grid structures on plasma characteristics in the discharge chamber: where I b is the ion beam, and A s and T s are the grid area and optical transparency (which is 67%), respectively.…”

Section: Test Results and Comparisonmentioning

confidence: 86%

“…Figure 1 shows the structure of the discharge chamber of a 30 cm diameter ion thruster developed by Lanzhou Institute of Physics (LIP) and a schematic diagram of the ion beam extraction process. As shown in figure 1, the 30 cm diameter ion thruster adopts the triple grid as an ionic optical system [6,7]. The discharge chamber structure is a typical combination of cylindrical and conical sections, and the screen grid and the accelerator grid load 1200 V and −220 V voltages, respectively.…”

Section: Introductionmentioning

confidence: 99%

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A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

Sun¹,

Long²,

Guo³

et al. 2022

Plasma Sci. Technol.

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The grid structure has significant effects on the discharge characteristics of ion thruster. The discharge performances of 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 others, and the parallelism of magnetic field isopotential lines and anode is basically 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 convex and concave grid 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 grid and the concave grid have better uniform distribution of electron temperature. Moreover, the collision frequency ratios show that axial ionization degree of the three models is the highest, and the flat grid has the highest discharge efficiency, then the convex grid, and the concave grid is the worst. The test and simulation results of 30 cm diameter ion thruster with 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 double charged ions and parameter setting in the model. The comparison error between 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 of electric potential distribution and the variation of focusing characteristics of the grids. With the 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 convex grid is a more reasonable choice for the higher power and larger diameter thrusters.

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Section: Test Results and Comparisonmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

Sun¹,

Long²,

Guo³

et al. 2022

Plasma Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In recent years, miniaturized ion thrusters have been widely studied [1][2][3][4][5][6][7][8], with different types of ionization chambers models and feedback-control models, which will be essentially important for the drag-free control task for space-based gravitational wave detection [15,16]. However, this voltage-current function can differ between ground and in-orbit operations and can be changed versus the conditions in space due to complicated effects [17][18][19][20][21][22]. It is best to find a method that reflects the real-time variation of the extraction voltage-current (V-I) function.…”

Section: Introductionmentioning

confidence: 99%

A neural network model relating extraction current characteristics with optical emission spectra for the purpose of a digital twin of miniaturized ion thrusters

Zhang¹,

Zhu²,

Wang³

et al. 2022

J. Phys. D: Appl. Phys.

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Miniaturized ion thrusters are one of the most important candidates in the task of drag-free control for space-based gravitational wave detection, whose thrust can be accurately tuned in principle by in-orbit monitoring and feedback controlling. This work investigates a neural network model (NNM) which can be used for real-time monitoring of the function relating the grid voltage and the extraction current of a miniaturized ion thruster by optical emission spectroscopy. This model is developed as a component of an ion thruster’s digital twin. A collisional-radiative model relates the plasma parameters in the discharge chamber of the thruster to the emission spectroscopy; an extraction current model relates the plasma parameters to the function relating grid voltage and extraction current. The neural network model is trained based on the dataset produced by these models, and is examined by experimental results from a miniaturized ion thruster. It is found that the difference between the thrust predicted by the NNM and the experimental value is less than 6%. Discussions are given on further improvement of the NNM for accurate thrust control in space-based gravitational wave detection in the future.

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“…A 30-cm diameter ion thruster is a high power (two work modes, 3 and 5 kW), high thrust (100 mN in 3 kW and 200 mN in 5 kW) ion thruster, which is designed for the new generation large-scale truss-type satellite platform in China (Sun et al 2020). In order to meet the performance demands of a 30-cm diameter ion thruster, a hollow cathode with a nominal 20 A emission current has been designed and manufactured as the primary electron source (Sun et al 2018a).…”

Section: Introductionmentioning

confidence: 99%

Computational and Experimental Study on the Discharge Model of a 20 Amperes Emission Current Hollow Cathode

Sun

Liu

2021

J. Aerosp. Technol. Manag.

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The discharge characteristics of hollow cathode directly affect the performance of thruster. In order to obtain the plasma parameters of the 20 A emission current hollow cathode, COMSOL software is used to simulate the potential distribution, neutral fluid distribution and plasma parameters of the cathode, then the test is carried out to verify the simulations. The results show that the fluid velocity in the emitter region is about 20 ms -1 and is uniform in the radial direction. The electron density throughout the cathode discharge zone is almost uniform within the range of 1.09 × 10 20 ~ 1.2 × 10 20 m -3 . The electron temperature increased from 2.8 to 4.9 eV throughout the cathode discharge zone. The electron collision frequency is in the order of 10 23 Hz. The test results show that the electron temperature is increased from 2.4 to 5.2 eV from outlet of the emitter region to the plume region, and which presents an opposite trend to the electron density. There is a small error between the test results and the simulation results, and this error is mainly caused by the flow boundary setting.

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Grid Gap Variation of Ion Thruster During Startup in Orbit

Cited by 8 publications

References 18 publications

A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

A study of the influence of different grid structures on plasma characteristics in the discharge chamber of an ion thruster

A neural network model relating extraction current characteristics with optical emission spectra for the purpose of a digital twin of miniaturized ion thrusters

Computational and Experimental Study on the Discharge Model of a 20 Amperes Emission Current Hollow Cathode

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