Three-dimensional geomagnetic field effects on a plasma thruster plume expansion

Cichocki, Filippo; Merino, Mario; Ahedo, Eduardo

doi:10.1016/j.actaastro.2020.05.019

Cited by 14 publications

(42 citation statements)

References 26 publications

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“…In order to respect the CFL condition, the time step is 0.25 µs, while the overall simulation time is 1.25 ms, sufficiently Coming now to the electron fluid model, this is the same as the one described in Ref. [25], but with a different numerical discretization strategy [31]. The model assumes a quasineutral plasma everywhere, i.e.…”

Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

“…Then, assuming both isotropic and polytropic electrons, the generalized Ohm's law can be derived from the electron momentum balance equation as [25]:…”

Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

“…where K is the normalized conductivity tensor (defined below), σ e = e 2 n e /(m e ] e ) is the electron scalar conductivity, j c is an effective current density grouping collisional effects with heavy species [25], and a "residual thermalized potential" Φ has been introduced. The latter is defined so that ∇Φ = ∇ϕ − ∇h e /e, being ϕ the electric potential and ∇h e = ∇p e /n e the barotropic function gradient (which is an exact differential when polytropic electrons are considered [25]).…”

Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

“…The 3D code EP2PLUS [23] makes use of this hybrid approach, and has already been used in different plasma thruster scenarios, from S/C-debris-plasma interaction in an ion beam shepherd scenario [24] to a plasma plume expansion under the geomagnetic field [25], including also simulations of 3D Hall thruster near plumes [26] and ion grid optics [27]. The magnetized electron model of Refs.…”

Section: Introductionmentioning

confidence: 99%

“…The magnetized electron model of Refs. [25,26] is particularly appropriate to simulate the plasma expansion across the divergent part of the magnetic nozzle of an electrodeless plasma thruster. Such a model features a quasineutrality assumption and solves the coupled electric current continuity and electron momentum balance equations, retaining both the electron collisions term and the very relevant magnetic force term, j e × B, where j e is the electron current density and B is the magnetic induction field.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic Nozzle and RPA Simulations vs. Experiments for a Helicon Plasma Thruster Plume

et al. 2022

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The experimental characterization of electrodeless plasma thrusters with a magnetic nozzle is fundamental in the process of increasing their maturity to reach the industrialization level. Moreover, it offers the unique opportunity of validating existing numerical models for the expansion of a magnetized plasma plume, and for the synthetic simulation of diagnostics measurements, like those of a retarding potential analyzer, which provides essential information regarding the ion beam energy distribution function. Simulations to experiments comparison ultimately enables a better understanding of the physical processes behind the observed experimental curves. In this work, input experimental data of a Helicon plasma plume is used to simulate both a magnetic nozzle expansion in the divergent field region, and the corresponding measurements of a retarding potential analyzer, through dedicated small-scale simulations of this diagnostics tool. Magnetic nozzle simulation and experimental results agree well in terms of the angular distribution of the ion current at 40 cm distance from the source, and also in the prediction of the energies of the two main peaks of the ion energy distribution function: a first one at 45 eV due to source ions, and a second one, at 15–20 eV, due to ions from charge-exchange and ionization collisions in the plume. Finally, the small-scale simulation of the retarding potential analyzer permits to assess the parasitic effects caused by the ion current collected by the different analyzer grids. The inclusion of the retarding and electron suppression grids currents in the overall I-V characteristic is shown to correct almost entirely these effects on the obtained ion velocity distribution.

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Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

“…Then, assuming both isotropic and polytropic electrons, the generalized Ohm's law can be derived from the electron momentum balance equation as [25]:…”

Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

Section: Magnetic Nozzle Expansion Model and Simulation Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic Nozzle and RPA Simulations vs. Experiments for a Helicon Plasma Thruster Plume

et al. 2022

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Using electron fluid models to analyze plasma thruster discharges

Ahedo

2023

J Electr Propuls

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Fluid models of the slow-dynamics of magnetized, weakly-collisional electrons lead to build computationally-affordable, long-time simulations of plasma discharges in Hall-effect and electrodeless plasma thrusters. This paper discusses the main assumptions and techniques used in 1D to 3D electron fluid models, and some examples illustrate their capabilities. Critical aspects of these fluid models are the expressions for the pressure tensor, the heat flux vector, the plasma-wall fluxes, and the high-frequency-averaged electron transport and heating caused by plasma waves, generated either by turbulence or external irradiation. The different orders of magnitude of the three scalar momentum equations characterize the electron anisotropic transport. Central points of the discussion are: the role of electron inertia, magnetically-aligned meshes versus Cartesian-type ones, the use of a thermalized potential and the infinite mobility limit, the existence of convective-type heat fluxes, and the modeling of the Debye sheath, and wall fluxes. Plasma plume models present their own peculiarities, related to anomalous parallel cooling and heat flux closures, the matching of finite plume domains with quiescent infinity, and solving fully collisionless expansions. Solutions of two 1D electron kinetic models are used to derive kinetically-consistent fluid models and compare them with more conventional ones.

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