Plume Divergence in the Hall Thruster

Fruchtman, A.; Cohen-Zur, A.

doi:10.2514/6.2004-3957

Cited by 4 publications

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“…3 A relatively long (~ 2 cm) ion acceleration region with a large voltage drop is usually located both inside the channel and outside the channel exit, where the fringing magnetic field can lead to defocusing of the ion beam. 3,4 The use of segmented electrodes along the thruster channel can provide additional control of the plasma flow in a Hall thruster. [5][6][7][8] The plume narrowing effect measured for molybdenum and carbon electrodes at low discharge voltages (≤300 V) 6,7 was attributed to the reduced voltage drop outside the channel exit.…”

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Operation of a segmented Hall thruster with low-sputtering carbon-velvet electrodes

Raitses¹,

Staack²,

Dunaevsky³

et al. 2006

Journal of Applied Physics

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Carbon fiber velvet material provides exceptional sputtering resistance properties exceeding those for graphite and carbon composite materials. A 2kW Hall thruster with segmented electrodes made of this material was operated in the discharge voltage range of 200–700V. The arcing between the floating velvet electrodes and the plasma was visually observed, especially, during the initial conditioning time, which lasted for about 1h. The comparison of voltage versus current and plume characteristics of the Hall thruster with and without segmented electrodes indicates that the magnetic insulation of the segmented thruster improves with the discharge voltage at a fixed magnetic field. The observations reported here also extend the regimes wherein the segmented Hall thruster can have a narrower plume than that of the conventional nonsegmented thruster.

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confidence: 99%

Operation of a segmented Hall thruster with low-sputtering carbon-velvet electrodes

Raitses¹,

Staack²,

Dunaevsky³

et al. 2006

Journal of Applied Physics

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“…Note that in keeping with our previous studies 6 the plasma plume narrowing effect of the segmented electrodes is likely associated with an increase of the electric field inside the channel leading to a reduction of the ion residence time in the acceleration region and thereby, possibly, reducing defocusing effect of radial pressure gradients and magnetic field curvature on ion trajectories. 3 If the electric field increases equal to or faster than d V , then it is a reduction of the electron mobility at high discharge voltages that can explain the measured V-I characteristic of this thruster. Plasma measurements are necessary for more consistent analysis of the electron mobility, which cannot be predicted by the existing Hall thruster models.…”

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“…However, the ion beam divergence is large, leading to erosion of the channel walls and making difficult the integration of the thruster with satellite. [2][3][4] The magnetic field curvature and electron pressure are among the factors, which can contribute to the beam divergence in Hall thrusters. 3 A relatively long (~ 2 cm) ion acceleration region with a large voltage drop is usually located both inside the channel and outside the channel exit, where the fringing magnetic field can lead to defocusing of the ion beam.…”

mentioning

confidence: 99%

“…[2][3][4] The magnetic field curvature and electron pressure are among the factors, which can contribute to the beam divergence in Hall thrusters. 3 A relatively long (~ 2 cm) ion acceleration region with a large voltage drop is usually located both inside the channel and outside the channel exit, where the fringing magnetic field can lead to defocusing of the ion beam. 3,4 The use of segmented electrodes along the thruster channel can provide additional control of the plasma flow in a Hall thruster.…”

mentioning

confidence: 99%

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Operation of a Segmented Hall Thruster with Low-sputtering Carbon-velvet Electrodes

Raitses¹,

Staack²,

Dunaevsky³

et al. 2005

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Electron-wall interaction in Hall thrusters

et al. 2005

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Electron-wall interaction effects in Hall thrusters are studied through measurements of the plasma response to variations of the thruster channel width and the discharge voltage.The discharge voltage threshold is shown to separate two thruster regimes. Below this threshold, the electron energy gain is constant in the acceleration region and therefore, secondary electron emission (SEE) from the channel walls is insufficient to enhance electron energy losses at the channel walls. Above this voltage threshold, the maximum electron temperature saturates. This result seemingly agrees with predictions of the temperature saturation, which recent Hall thruster models explain as a transition to space charge saturated regime of the near-wall sheath. However, in the experiment, the maximum saturation temperature exceeds by almost three times the critical value estimated under the assumption of a Maxwellian electron energy distribution function.The channel narrowing, which should also enhance electron-wall collisions, causes unexpectedly larger changes of the plasma potential distribution than does the increase of the electron temperature with the discharge voltage. An enhanced anomalous crossed field mobility (near-wall or Bohm-type) is suggested by a hydrodynamic model as an explanation to the reduced electric field measured inside a narrow channel. We found, however, no experimental evidence of a coupling between the electron temperature and the location of the accelerating voltage drop, which might have been expected due to the SEE-induced near-wall conductivity.2

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Plume Divergence in the Hall Thruster

Cited by 4 publications

References 0 publications

Operation of a segmented Hall thruster with low-sputtering carbon-velvet electrodes

Operation of a segmented Hall thruster with low-sputtering carbon-velvet electrodes

Operation of a Segmented Hall Thruster with Low-sputtering Carbon-velvet Electrodes

Electron-wall interaction in Hall thrusters

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