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Studies of Hall Effect Thruster Plasmas

Professor Zbigniew Peradzyński Dr Serge Barral

Msc Marcin KolanowskiDr Jacek Kurzyna

Dr Karol Makowski

Research is made in collaboration with the French Research Group“Plasma Propulsion for Space Systems”

GDR 2759 CNRS/CNES/SNECMA/Universités) and coordinated by Professor Michel Dudeck

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Schematic view and a photo of SPT-100-MLHall Effect thruster.

specific impulse ~3000 s, thrust e.g.~ 1 N at thepower of 50 kW, non limited operation time

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Ground testing facility PIVOINE at Laboratoired'Aérothermique at CNRS Orléans, France.

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About Stationary Plasma Thrusters and fluid models

Description of HALL EFFECT THRUSTER:

Stationary plasma thruster are plasma accelerators using crossed magnetic and electric field configuration in order to accelerate ions

Use of HALL EFFECT THRUSTER: orbit control of geostationary satellites orbit transfer of low orbit satellites space probe propulsion (SMART 1)

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Fluid Modelling :1 and 2D Fluid models are being developed with the following goals: reducing the computation time required by current kinetic and hybrid kinetic/fluid models. This would make fluid models very suitable for engineering analysis giving more insight on the the discharge processes: the mathematical statement of fluid models exhibit more clearly such phenomena like e.g. ion sonic transition, creating sheath on plasma-wall interface or excitation of plasma oscillations. In our formulation we use three-fluid description of plasma and particularly we assume:

•axial symmetry•electric neutrality•cold fluid approximation of neutrals and ions•negligible electron inertia in electron momentum balance

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Under above assumptions fluid models are composed of the followingequations:

● ion continuity ● atom continuity● ion momentum ● electron energy

Electric field is calculated basing on electric neutrality and constant dischargevoltage appearing as a boundary condition.

Main results:● transient solutions exhibiting breathing mode oscillations were

achieved for different operating conditions (discharge voltage, masflow rate, maximum magnetic field) and wall materials with differentsecondary electron emission coefficients

● linear stability analysis of steady state solutions has been madeexhibiting the appearance of unstable modes of frequencies scaledby inverse of ion time of flight in the acceleration zone

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0

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0.00 0.02 0.04 0.06 0.08 0.10 0.12

Tota

l cu

rrent

(A)

Time (ms)

delta=0.0050delta=0.0060delta=0.0065delta=0.0070delta=0.0075

Breathing mode current oscillations for different walls materials

The electron secondary emission of the walls τ (ε ) can be characterized (according toSternglass theory) by two parameters:

τmax: maximum secondary emission εmax: corresponding electron energy

τ ε=delta∗ε ; delta=τmax

εmax

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Breathing mode and transit time oscillations in Hall Effect Thruster plasma

Total discharge current according tothe solution of fluid model.

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Main types of Hall Effect Thruster plasma oscillations

According to theoretical studies, numerical modelingand experimental results three main plasma oscillationsfrequency bands can be distinguished in Hall EffectThruster:

● low range – of ~30 kHz (breathing mode)● medium range – of 0.1÷1 MHz (transit time)● high frequency range ≳10 MHz (electrostatic

azimuthal wave)

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EMD method as a tool for mode extraction

from nonstationary time series

In experiments global andlocal plasma parametersare registered asnonstationary time series.To study instantaneousfrequencies EMD method isapplied. It is a self-adaptiveroutine that extracts fromthe whole signal asequence of oscillatingmodes. Each moderepresents its own uniquetime scale. Usually amongthose modes one canidentify physical modesmentioned above.

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Bibliography:

1.S. Barral, K. Makowski, Z. Peradzyński, M. Dudeck, «Transit-timeinstability in Hall Thrusters», Physics of Plasmas, vol. 12, 073504(2005).

2.J. Kurzyna, S. Mazouffre, L. Albarede, G. Bonhomme, K. Makowski,M. Dudeck and Z. Peradzyński, « Spectral analysis of Hall effectthruster plasma oscillations based on the Empirical Modedecompostion» Physics of Plasmas, vol. 12, 123506 (2005).

3.S. Barral, K. Makowski, Z. Peradzynki, N. Gascon, M. Dudeck, «Wallmaterial effects in stationary plasma thrusters II : Wall conductivitytheory», Physics of Plasmas, vol. 10, pp. 4137-4152 (2003).

4.J. Kurzyna, N. Gascon, G. Bonhomme, M. Dudeck, K. Makowski, V.Lago, A. Lebéhot, Z. Peradzyński, «Oscillation of the dischargecurrent in a Stationary Plasma Thruster», High Temperature andMaterial Processes. An Int. Journal, vol. 6 pp. 181-190 (2002).

5.K. Makowski, Z. Peradzyński, S. Barral, M. Dudeck, «Review of theplasma fluid models in Stationary Plasma Thrusters», HighTemperature Material Processes. An Int. Journal, vol.5, No. 2, pp.277- 284 (2001).

Thank you for your attention!