Effect of a decel electrode on primary and charge-exchange ion trajectories

Meadows, G.; Free, B.

doi:10.2514/6.1975-427

Cited by 8 publications

(5 citation statements)

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“…Research has shown, however, that increasing the magnitude of the accel voltage causes an increase in the divergence of the ion beam. 32 The problems of both the divergence and accel grid erosion on its downstream surface can be addressed by installing a third (decel) grid downstream of the accel grid. This third grid is maintained at a potential near that of the ambient space plasma.…”

Section: Grid System Lifetimesmentioning

confidence: 99%

“…To some extent, it provides a physical shield against erosion on the downstream surface of the accel grid, and it helps to maintain the focus of the ion beamlets, thereby reducing the overall beam divergence over a wide range of accel-grid potentials. 32 A decel grid adds the mechanical complication of maintaining the position of a third closely spaced grid, but it has the benecial effect of shifting most of the accel grid charge-exchange sputter erosion from its downstream surface to the cylindrical (barrel) regions on the apertures. 33 Barrel erosion has a lesser effect on accel grid lifetime because the initial accel grid hole diameter is quite small and the time required to erode it to the point where the accel grid would fail mechanically is long.…”

Section: Grid System Lifetimesmentioning

confidence: 99%

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Ion Thruster Development Trends and Status in the United States

Wilbur

Rawlin

Beattie³

1998

Journal of Propulsion and Power

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The current interest in ion thrusters for near-Earth and deep-space missions has occurred because of long-term development efforts yielding an understanding of the physical phenomena involved in thruster operation and hardware that is suited to a wide range of missions. Features of state-of-the-art thrusters are described in terms of the various physical processes that occur within them. Tradeoffs that must be considered to arrive at thruster designs suited to commercialization are discussed.

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Section: Grid System Lifetimesmentioning

confidence: 99%

Section: Grid System Lifetimesmentioning

confidence: 99%

Ion Thruster Development Trends and Status in the United States

Wilbur

Rawlin

Beattie³

1998

Journal of Propulsion and Power

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“…In order to prevent the accelerator structural failure caused by the Pit and Groove erosion, a decelerator grid is introduced to the classical 2-grid optical system. Many ion thruster tests have shown that the decelerator grid can significantly reduce the Pit and Groove erosion [1][2][3]. However, the effects of the decelerator grid on the optical system, such as on the extraction process of beam ions and CEX ions, have not been fully studied.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Decelerator Grid on the Optical Performance of the Ion Thruster

Zhao²,

Wan

et al. 2019

International Journal of Aerospace Engineering

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In order to reduce the erosion of the ion thruster accelerator grid, which is caused by charge-exchange (CEX) ions, the 2-grid optical system is added to a decelerator grid to block the reflux CEX ions. The previous experiment and simulation results have proven that the decelerator grid can effectively reduce the Pit and Groove erosion. However, the influence of the decelerator grid on the optical performance has not yet been studied well. In this paper, a three-dimensional Immersed Finite Element Method-Particle in Cell-Monte Carlo Collision (IFE-PIC-MCC) algorithm was adopted to investigate the effect of the decelerator grid on the optical performance under crossover and normal circumstances. Results show that the decelerator grid has no effect on the focusing state and the distribution of beam ions. It also has little effect on the CEX ions from the upstream and extraction (center) regions. However, it has great influence on the downstream CEX ions. When the upstream plasma number density is small, the decelerator grid will cause most of the downstream reflux CEX ions to impinge on the accelerator grid aperture barrel, resulting in the significant increase of the Barrel erosion of the accelerator grid. With the increase of the upstream plasma number density, the downstream reflux CEX ions tend to impact the downstream surface of the decelerator grid, which means the decelerator grid begins to block the downstream backflow of CEX ions.

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“…At the lower value, ions begin to directly intercept the negative grid and the higher value i s about the point where ion beam electrons begin to backstream into the thruster. Data have been recently been talien(l3, 14) which indicate that values of R between about 0. 2 and 0.9 a r e allowable with three grid accelerator systems.…”

Section: Element Description Thrustermentioning

confidence: 99%

“…In the opinion of the authors, advanced thrusters will be of the three grid type, (13,14) utilize a more complicated magnetic field configuration, (15916) and operate at higher power densities than the baseline thruster. A preliminary calculation of the impact of these approaches indicated that a circular 30-cm thruster would have a mass of 11.4 kg when operated at power densities of about a factor of five greater than the baseline thruster.…”

Section: Element Description Thrustermentioning

confidence: 99%