Effect of anisotropy of electron velocity distribution function on dynamic characteristics of sheath in Hall thrusters

In Hall thrusters, the electron velocity distribution function is not only depleted at high energies, but also strongly anisotropic. With these electrons interacting with the channel wall, the sheath will be changed in its dynamic characteristics. In the present letter, a two dimensional particle-in...

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Bibliographic Details
Published in:Physics of plasmas 2011-10, Vol.18 (10), p.103512-103512-3
Main Authors: Zhang, Fengkui, Ding, Yongjie, Li, Hong, Wu, Xiande, Yu, Daren
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANISOTROPY
COLLISIONLESS PLASMA
DISTRIBUTION FUNCTIONS
ELECTRON TEMPERATURE
ELECTRONS
ION TEMPERATURE
MAGNETOHYDRODYNAMICS
OSCILLATIONS
PLASMA SHEATH
PLASMA SIMULATION
PLASMA WAVES
POTENTIALS
THRUSTERS
TWO-DIMENSIONAL CALCULATIONS
WALL EFFECTS
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Summary:In Hall thrusters, the electron velocity distribution function is not only depleted at high energies, but also strongly anisotropic. With these electrons interacting with the channel wall, the sheath will be changed in its dynamic characteristics. In the present letter, a two dimensional particle-in-cell code is used to simulate these effects in a collisionless plasma slab. The simulated results indicate that the sheath changes from steady regime to temporal oscillation regime when the electron velocity distribution function alters from isotropy to anisotropy. Moreover, the temporal oscillation sheath formed by the anisotropic electrons has a much greater oscillating amplitude and a much smaller average potential drop than that formed by the isotropic electrons has. The anisotropic electrons are also found to lower the critical value of electron temperature needed for the appearance of the spatial oscillation sheath.
ISSN:1070-664X
1089-7674
DOI:10.1063/1.3654052