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Computational modeling of the plasma located in the discharge chamber of an ion engine is an important activity so that the development and design of the next generation of ion engines may be enhanced. In this work a computational tool called XOOPIC is used to model the primary electrons, secondary electrons, and ions inside the discharge chamber....
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... The second, most complete model created in that period is an axisymmetric model developed by S. Mahalingam and colleagues. The first publication with the preliminary results of this study is dated 2005 and is devoted to the motion of individual plasma components in discharge chamber [13]. Soon, papers [14][15][16] describing the new model were published. ...
... As mentioned earlier, a good agreement between simulations and experiment was obtained by several authors who used different approaches to accounting for the anomalous electronic conductivity. In studies on the modeling of discharge chambers [13,16,21] similar in setting to the one on scheme (b), it was possible to calculate without additional diffusion at all. In our simulation, a relatively small value of the diffusion coefficient was indeed obtained. ...
The axisymmetric particle-in-cell model was used to simulate two discharge chambers of similar sized ion thrusters. The difference between discharge chambers was the type of magnetic system and, consequently, the topology of the applied magnetic field. Similar modes of operation are chosen for modeling. During the simulation, the level of anomalous electronic conductivity was selected in such a way as to achieve maximum agreement with the experimental data in each of the two cases. It was obtained that in a discharge chamber with magnetic coils the level of anomalous electronic conductivity is almost three times higher than in a similar discharge chamber with permanent cusp magnets.
... In the works that followed, Hagelaar et al. [11][12][13][14] expanded on that simulation to analyze the impact of the magnetic field on thruster performance. While these works and others [15][16][17][18][19][20] do focus on plasma wall interactions to varying degrees, their limit lies in the fact that neutrals were either not included or treated as background particles. Moreover, a comprehensive study of the impact of neutral recycling phenomena on performance as well as neutral density has not been carried out, hence the motivation for our work. ...
The gas inlet configuration has a direct impact on the neutral density pattern within a miniature ion thruster. We aimed to investigate the impact the gas inlet configuration and neutral density pattern will have on the neutral recycle rate within a miniature ion thruster utilizing a disk shaped antenna. Four inlet configurations were considered for this study, and 3D electromagnetic particle-in-cell simulation was utilized to simulate the plasma inside the discharge chamber. The simulation results indicate a clear shift in neutral density toward the inlet, with the single horizontal inlet configuration having a 45% increase in neutral density in the vicinity of the inlet walls. The neutral recycle rate also experienced a clear shift toward the inlet walls, with the single bottom inlet configuration experiencing a 23% increase in the rate of ion loss near the inlet wall and a similar 22% increase for the single horizontal inlet while the four smaller inlets had a similar rate of neutral recycling throughout. These results are a novelty in this field as they clearly indicate the impact gas inlet and neutral density have on the miniature ion thruster’s performance and open a new area of research to further optimize the gas inlet configuration for miniature ion thrusters.
... To reduce the simulation time, researchers have adopted different approaches to calculate the neutrals. The neutral distribution change is much smaller and slower than the change of ions and electrons, so Mahalingam et al. applied a fixed-neutral model 9,22 to avoid the high computation of the neutrals. In this method, neutral change is assumed to be neglected so that the neutral distribution has been set to be uniform in the discharge chamber or to be a constant background distribution simulated by a lower gas flow rate 23 . ...
Particle in cell-Monte Carlo collision method is accurate for electric propulsion
simulation, but so time-consuming mainly because of two aspects. The first one is that the huge number of particles make the simulation dramatically slow in a serial way. The other is that the neutrals move much slower than other species, delaying the whole simulation into convergent. In this paper, focusing on these two problems, we develop a set of parallel codes and use a new method to simulate neutrals and simulate a cylinder hall thruster for testing. The parallel codes are based on the particle decomposition, which is suitable for relatively
small scale plasma simulation. The highest speedup of the parallel PIC-MCC code comes to 16 compared with the serial one, showing good performance. On the other side, view factor model is combined into the serial PIC-MCC code. This method use view factor to calculate and update the 3D neutral distributions periodically, making the simulation both accurate and fast. The physical progress is more close to the real after combining view factor model with PIC-MCC code.
... Our initial simulation work on a 9.2 cm diameter discharge chamber showed that the simulation time to reach 1 µs is 30 days on a single processor [Mahalingam and Menart 2005]. This simulation used a 1000x500 uniform mesh, a time step value of 2×10 −12 s, and 9 million computer particles. ...
A particle-based model with a Monte Carlo collision model has been developed to study the plasma inside the discharge chamber of an ion engine. This model tracks five major particle types inside the discharge chamber in detail: xenon neutrals, singly charged xenon ions, doubly charged xenon ions, secondary electrons, and primary electrons. Both electric and magnetic field effects are included in the calculation of the charged particle's motion. The electric fields inside the discharge chamber are computed using a new approach. Also, detailed particle collision mechanisms are enabled. Validation of this computational model has been made on NASA's three-ring Solar Electric Propulsion Technology Application Readiness Program discharge chamber, at the 2.29 kW input power, 1.76 A beam current, and 1100 V beam voltage operating condition. Comparisons of numerical simulation results with experimental measurements are found to have good agreement. The computed ion beam current differs from experiments by 1% and the computed discharge current differs from experiments by 22%. The plasma ion production cost compares within 7% and the beam ion production cost compares within 16% of the experimental values. The overall computed thruster efficiency is found to differ from experiments by 11%. In addition, steady-state results are given for particle number density distributions, kinetic energy, particle energy loss mechanisms, and current density collected at the chamber walls.
Vertically aligned freestanding gold nanowires (AuNWs) were synthesized and deposited on one of the electrodes of a capacitor-like gas ionization cell, whereas the counterelectrode was a polished silicon wafer coated with aluminum on both sides. The field enhancement property of high-aspect-ratio AuNWs was employed to reduce the gaseous breakdown voltage (Vb) at room temperature. The device was characterized in low-pressure air, and tested in subtorr argon where it demonstrated a considerable reduction in Vb compared with uniform field conditions and with its earlier counterparts. The dependences of Vb and prebreakdown currents on the polarity of applied voltage were studied. A particle-in-cell/Monte-Carlo-collision (PIC/MCC) model for the device was also developed to simulate the breakdown process within the same pressure range in which measurements were carried out. The simulated Vb-P curve showed good agreement with the measured characteristics.
Electric propulsion thrusters are replacing small chemical thrusters used for spacecraft control and orbital maneuvers. These thrusters use a variety of mechanisms to convert electrical power into thrust and in general provide superior specific impulse in comparison to chemical systems. Electric propulsion has been under development for the last fifty years, and almost all thrusters are designed based largely on experience and experimentation. The present article considers the progress made in numerical simulation of electric propulsion thrusters. Due to the wide range of such devices, attention is restricted to electric propulsion thruster types that are presently in use by orbiting spacecraft. The physical regimes created in these thrusters indicate that a variety of numerical methods are required for accurate numerical simulation ranging from continuum formulations to kinetic approaches. Successes of numerical simulation models are demonstrated through specific examples. It is concluded that numerical simulations can be expected to play a more prominent role in the design and evolution of future electric propulsion thrusters.
There is a clear current trend towards the replacement of small chemical thrusters used for spacecraft control by electric propulsion thrusters. These thrusters use a variety of mechanisms to convert electrical power into thrust and, in general, provide superior specific impulse in comparison to chemical systems. Electric propulsion has been under development for the last 40 yr, and almost all thrusters are designed based on experience and experimentation. The present article considers the progress made in numerical simulation of electric propulsion thrusters. Due to the wide range of such devices, attention is restricted to electric propulsion thruster types that are presently in use by orbiting spacecraft. The physical regimes created in these thrusters indicate that a variety of numerical methods is required for accurate numerical simulation ranging from continuum formulations to kinetic approaches. Successes of numerical simulation models are demonstrated through specific examples. It is concluded that numerical simulations can be expected to play a more prominent role in the design and evolution of future electric propulsion thrusters.
