Geometric effects in applied-field MPD thrusters

Myers, Roger; Mantenieks, M. A.; Sovey, James S.

doi:10.2514/6.1990-2669

Cited by 15 publications

(5 citation statements)

References 8 publications

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“…It is important to note that, even though the Tikhonov semiempirical thrust model [2,10] was derived for the lithium MPD thruster class built in MAI, it captures the same trends observed when operating other AF-MPDTs in other facilities at a variety of thruster power values, thruster geometries, and propellants [17,[22][23][24][25]. These trends show a linear increase of thrust with an increase in the product JB.…”

Section: Experimental Observationsmentioning

confidence: 99%

Scaling of Efficiency with Applied Magnetic Field in Magnetoplasmadynamic Thrusters

Lev

Choueiri

2012

Journal of Propulsion and Power

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Section: Experimental Observationsmentioning

confidence: 99%

Scaling of Efficiency with Applied Magnetic Field in Magnetoplasmadynamic Thrusters

Lev

Choueiri

2012

Journal of Propulsion and Power

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“…10 In this study, however, the degree of ionization was on the order of 1 O·~ to 10-4 for anode surface pressures between 1.3 Pa and 13 Pa (0.01 torr and 0.10 torr), respectively, so that electron collisions with neutrals were significant. The electron Hall parameter was therefore modified to include the electron-neutral collision frequency, derived from Reference 35, and is given by:…”

Section: Errect Of Applied Magnetic Field Strength and Orientationmentioning

confidence: 51%

Mechanisms Of Anode Power Deposition In A Low Pressure Free Burning Arc

Soulas

Myers

1992

IEEE Conference Record - Abstracts. 1992 IEEE International Conference on Plasma

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Anode power deposition is R dominant power loss mechanism for Rrcjets Rnd IVIPD thrusters. In this study, a free burning arc experiment was operated at pressures and current densities similar to those in arcjets and MPD thrusters in an attempt to identify the physics controlling lhis loss mechanism. Use of a free burning arc allowed for the isolation of independent variables controlling anode power depQsition and provided a convenient and flexible way to cover a broad range of currents, anode surface pressures, and applied magnetic field strengths and orientations using an argon gas. Test results showed that anode power deposition decreased with increasing anode surface pressure up to 6.7 Pa (0.05 torr) and then became insensitive lo pressure. Anode power incrl'nsed with increasing arc current while the electron number density near the anode surface increased linearly. Anode power also increased with increasing applied magnetic field strength due to an increasing anode fall voltage. Applied magnetic field orientation had an effect only at high currents and low anode surface pressures, where anode power decreased when applied field lines Intercepted the anode surface. The results demonstrated that anode power deposition was dominated by th e current-carr)'ing electrons and that the anode fall voltage was the largest contributor. Furthermore, the results showed that anode power deposition can be reduced by operating at increased anode pressures, reduced arc currents and applied magnetic field strengths, and with magnetic field lines intercepting the anode. anode power, W e electron charge, 1.60 x 10. 19 C P conv convected power to the anode, W J.anode current, A ' P"'" radiated power to the anode, W J are arc current, A r l electron gyro radius, m J e electron current, A T.anode surface temperature, K J e ml.• electron thermionic emission current from the T. IntroductionAnode power deposition is currently a dominant power loss mechanism for high performance electric propUlsion devices. Thermal arcjets and steady-state magnetoplasmadynamic (MPD) accelerators, which pass a discharge cun'ent through the propellant plasma to heat and accelerate the gas, deposit between 15% and 80% of the input power into the anode. Not only is tills a severe performance penalty, but it introduces thermal design problems since the heat must be radiated from the thmster.Typical arcjet and MPD thruster designs are shown in Figw'e 1. Anode power-to-input power percentages (anode power fractions) are currently 15-20% for arcjets operating at 1 kW I and ~ 50% for steady-state MPD thrusters. l Arcjets are presently baselined for station-keeping applications on geosynchronous communication satellites because their hiah b exhaust velocities permit large fuel savings. MPD thmsters are currently being studied for higher power applications, including orbit raising and planetary missions. These missions require input power-tothmst power conversion efficiencies (thrust efficiencies) between 0.4 and 0.6/ which, given the presence of other loss mech...

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“…Second, Mikellides and Turchi predict T AF ∝ √ JB A whereas it has long been assumed and repeatedly verified experimentally to be proportionate to JB A . 1,15,[21][22][23] Also worth noting is that the inverse dependence on l c , as with the Myers model, makes this model incompatible with certain thruster geometries.…”

Section: Krülle Model:mentioning

confidence: 99%

A Critical Review of Thrust Models for Applied-Field Magnetoplasmadynamic Thrusters

Coogan

Choueiri

2017

53rd AIAA/SAE/ASEE Joint Propulsion Conference

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A critical review of published thrust models for applied-field magnetoplasmadynamic thrusters is presented, along with a new model addressing shortcomings related to electrode and magnet geometry. While numerous theoretical thrust models have been presented in the literature, there has not been a comprehensive comparison to determine which best predicts thruster behavior across a large parameter space. In order to make this determination, all thrust data available in the literature were collected into a single database and tested against each model. Unlike previous comparisons between prediction and measurement, only the regime in which the applied-field thrust component dominates is examined, allowing for a direct comparison without invoking models of self-field and gasdynamic components of thrust. The degree to which each model deviates from measurement is determined for each controllable parameter. It is found that the largest deviations are due to incorrect representation of the effects of electrode and solenoid geometries. In light of this comparative study, an improved empirical model is derived as a function of nondimensional parameters representing these geometric variables. The improved agreement is attributed to the effects of magnetic field topology near the anode, which sets the effective anode radius that controls the magnitude of the Lorentz force for certain electrode geometries.

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Geometric effects in applied-field MPD thrusters

Abstract: Three applied-field MPD thruster geometries were tested with argon propellant to establish the influence of electrode geomety on thruster performance.

Cited by 15 publications

References 8 publications

Scaling of Efficiency with Applied Magnetic Field in Magnetoplasmadynamic Thrusters

Scaling of Efficiency with Applied Magnetic Field in Magnetoplasmadynamic Thrusters

Mechanisms Of Anode Power Deposition In A Low Pressure Free Burning Arc

A Critical Review of Thrust Models for Applied-Field Magnetoplasmadynamic Thrusters

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