Collisionless ion modeling in Hall thrusters: Analytical axial velocity distribution function and heat flux closures

The genesis of the ion axial velocity distribution function (VDF) is analyzed for collisionless Hall thruster discharges. An analytical form for the VDF is obtained from the Vlasov equation, by applying the Tonks–Langmuir theory in the thruster channel, under the simplifying assumptions of monoenerg...

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Veröffentlicht in:Physics of plasmas 2020-07, Vol.27 (7), Article 073506
Hauptverfasser: Boccelli, S., Charoy, T., Alvarez Laguna, A., Chabert, P., Bourdon, A., Magin, T. E.
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Sprache:eng
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Zusammenfassung:The genesis of the ion axial velocity distribution function (VDF) is analyzed for collisionless Hall thruster discharges. An analytical form for the VDF is obtained from the Vlasov equation, by applying the Tonks–Langmuir theory in the thruster channel, under the simplifying assumptions of monoenergetic creation of ions and steady state. The equivalent set of 1D unsteady anisotropic moment equations is derived from the Vlasov equation, and simple phenomenological closures are formulated, assuming a polynomial shape for the ion VDF. The analytical results and the anisotropic moment equations are compared to collisionless particle-in-cell simulations, employing either a zero heat flux (Euler-like equations) or the polynomial-VDF closure for the heat flux. The analytical ion VDF and its moments are then compared to experimental measurements.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0006258