Micropropulsion research at AFRL

Gulczinski, Frank S.; Dulligan, M. J.; Lake, James; Spanjers, Gregory G.

doi:10.2514/6.2000-3255

Cited by 22 publications

(11 citation statements)

References 6 publications

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“…Various attempts have been conducted to miniaturize pulsed plasma thrusters in the recent years [15,16]. A common problem in these efforts was the carbonization of the Teflon surface.…”

Section: Miniaturized Pulsed Plasmamentioning

confidence: 99%

Development of Electric and Chemical Microthrusters

Scharlemann

2011

International Journal of Aerospace Engineering

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The increasing application of microsatellites (from 10 kg up to 100 kg) as well as CubeSats for a rising number of various missions demands the development of miniaturized propulsion systems. Fotec and The University of Applied Sciences at Wiener Neustadt is developing a number of micropropulsion technologies including both electric and chemical thrusters targeting high performance at small scales. Our electric propulsion developments include a series of FEEP (field emission electric propulsion) thrusters, of which the thrust ranges from µN to mN level. The thrusters are highly integrated into clusters of indium liquid-metal-ion sources that can provide ultralow thrust noise and long-term stability. We are also developing a micro PPT thruster that enables pointing capabilities for CubeSats. For chemical thrusters, we are developing novel micromonopropellant thrusters with several hundred mN as well as a 1-3 N bipropellant microrocket engine using green propellants and high specific impulse performance. This paper will give an overview of our micropropulsion developments at Fotec, highlighting performance as well as possible applications.

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“…Various attempts have been conducted to miniaturize pulsed plasma thrusters in the recent years [15,16]. A common problem in these efforts was the carbonization of the Teflon surface.…”

Section: Miniaturized Pulsed Plasmamentioning

confidence: 99%

Development of Electric and Chemical Microthrusters

Scharlemann

2011

International Journal of Aerospace Engineering

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“…Equation C.3 [Guman, 1975] does not apply to the regime that the micro-PPT designs (those with Ibit -5 gNs) lie in, so supplementary data [Gulczinski, 2000] was used to obtain a reasonable value for the mshot, which was then used in Equation C.4 to determine a corresponding Ibit- which equates the average power the thruster needs to consume to the average power the spacecraft must produce for it with a power transmission efficiency factor (assumed to be 0.85) and an assumed spacecraft voltage of 28 V. The following three equations for the mass of various propulsion system components comes from the same paper by Guman that is the source for Equation C. 1 [Guman, 1975] and is based on experimental data. …”

Section: 2mentioning

confidence: 99%

Micropropulsion system selection for precision formation flying satellites

Reichbach

2001

37th Joint Propulsion Conference and Exhibit

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Several upcoming scientific interferometry missions (ST-3, LISA, TPF, MAXIM and SPECS) will push the limits of precision positioning of satellites. These spacecraft will require position and attitude control actuation on exceedingly small scales, which has not previously been performed. The several candidate propulsion systems for these missions include: colloid thrusters, field emission electrostatic propulsion thrusters (FEEP), pulsed plasma thrusters (PPT) and miniature cold gas thrusters. In order to assess the appropriateness of each of the candidate micropropulsion systems, a model of each is constructed. The models created are conglomerations of basic physical concepts and empirically founded relationships. Emphasis is placed on the determination of key operating parameters that are most relevant to design at the system level. Along with models of propulsion system performance, a common set of higher level metrics based on the GINA (Generalized Information Network Analysis) method is defined to allow the various propulsion concepts to be compared. High-level propulsion system design has been performed for each mission, employing the propulsion models created. These designs are evaluated according to the metrics developed and judgements are made as to which propulsion system is the most useful for each set of requirements.

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“…Inspection of the micro-PPT propellant surface after firing indicated signs of charring and preferential ablation near the electrodes. 8,9,13 It was identified that char formation is the main failure mechanism in the case of low energyto-thruster-radius ratio. 13 In this paper we present results of microscopic analyses of the charred areas and propose a mechanism of char formation.…”

mentioning

confidence: 99%

“…8,9,13 It was identified that char formation is the main failure mechanism in the case of low energyto-thruster-radius ratio. 13 In this paper we present results of microscopic analyses of the charred areas and propose a mechanism of char formation. To understand this phenomenon, a model of the plasma layer near the Teflon TM surface is developed.…”

mentioning

confidence: 99%

Propellant Charring in Pulsed Plasma Thrusters

Keidar¹,

Boyd²,

Antonsen

et al. 2004

Journal of Propulsion and Power

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The Teflon TM ablation in a micro-pulsed plasma thruster is studied with the aim of understanding the charring phenomenon. Microscopic analysis of the charred areas shows that it contains mainly carbon. It is concluded that the carbon char is formed as a result of carbon flux returned from the plasma. A simplified model of the current layer near the Teflon surface is developed. The current density and the Teflon surface temperature have peaks near the electrodes that explain preferential ablation of these areas, such as was observed experimentally. Comparison of the temperature field and the ablation rate distribution with photographs of the Teflon surface shows that the area with minimum surface temperature and ablation rate corresponds to the charring area. This finding suggests that the charring may be related to a temperature effect.

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Micropropulsion research at AFRL

Cited by 22 publications

References 6 publications

Development of Electric and Chemical Microthrusters

Development of Electric and Chemical Microthrusters

Micropropulsion system selection for precision formation flying satellites

Propellant Charring in Pulsed Plasma Thrusters

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