Plume Characterization of Electric Solid Propellant Pulsed Microthrusters

Glascock, Matthew S.

doi:10.2514/1.b36271

Cited by 30 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Pulsed plasma thrusters (PPTs) are a form of electric propulsion for spacecraft [1][2][3][4][5]. They were first deployed in orbit on the Zond-2 spacecraft in 1964 [6] and are highly suitable for small satellites [7], especially with the recent discovery of promising alternative propellants [5,[8][9][10]. As suggested by their name, they operate in a pulsed mode triggered by a spark plug.…”

Section: Introductionmentioning

confidence: 99%

In-plume acceleration of leading-edge ions from a pulsed plasma thruster

Ling

Zhang

Tang

et al. 2018

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

Pulsed plasma thrusters are a form of electric propulsion for spacecraft. Their research has undergone recent growth due to an increasing interest in small satellites. However, their plasma plumes are transient and challenging to study due to the extremely short discharge time that lasts in the order of microseconds. The plasma plume is accelerated by a combination of electrothermal and electromagnetic forces. With electromagnetic acceleration, the ions are typically thought to be only accelerated within the thruster by the Lorentz force. Estimated downstream exhaust velocities have ranged widely from 5 to 60 km s −1 , with values on the lower end corresponding to electrothermal acceleration. However, we show here that the fastest leading-edge ions continue to accelerate in the plume even in the absence of electromagnetic forces. Pulsed plasma thruster plumes are composed of electrons and a mixture of ion species with different ionization levels. Due to this quasi-neutrality of the plasma plume with electrons featuring much larger velocities than ions, we suggest that the acceleration might be ambipolar in nature. The leading-edge ions eventually reach velocities in excess of 100 km s −1 , far greater than values typically associated with electrothermal acceleration. This indicates that care must be taken in the accurate measurement of the ion velocity in the plume. The ion plume may also be more energetic than previously believed. Furthermore, we also propose that simple extrapolation can be used to determine the actual exit plane ion velocity; this value can be used as accurate input data for future simulations.

show abstract

Section: Introductionmentioning

confidence: 99%

In-plume acceleration of leading-edge ions from a pulsed plasma thruster

Ling

Zhang

Tang

et al. 2018

Plasma Sources Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…Experimental results are used to determine an effective exhaust velocity of the plume and temporally correlated to high speed images. Table II details the results of the mass balance measurements made of twenty microthrusters tested, both during this work, as well as in previous work 16,17 . The average mass bit (m bit ) is calculated by subtracting the final from initial mass and dividing by the number of pulses.…”

Section: Resultsmentioning

confidence: 99%

Observation of Late-Time Ablation in Electric Solid Propellant Pulsed Microthrusters

Glascock

Rovey

Williams

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

Self Cite

View full text Add to dashboard Cite

Electric solid propellants are an interesting potential option for propulsion because they are ignited by an applied electric current. The electric nature of these materials leads to the capability for use in pulsed electric propulsion devices. In this work, the ablation process of an electric solid propellant during pulsed microthruster operation is investigated using a triple Langmuir probe, thrust stand and high speed video camera. Results include quantitative time-of-flight, ablation mass per pulse and impulse-per-pulse measurements. Additionally, qualitative images from the high speed video are temporally correlated to these measurements. Analyses indicate 45±11% of the ablated mass per pulse is expelled at negligible speeds relative to the effective plume exhaust velocity (1500 m/s). Further, this occurs on a time scale that is three times longer than the 0.5 ms primary discharge. This late-time ablation has been identified in other pulsed microthrusters with traditional Teflon propellant, and the results presented here indicate that electric solid propellant exhibits similar behavior.

show abstract

“…An interesting point that needs to be stated is that the canting phenomenon only appears in thrusters with parallel electrodes, while the asymmetry disappears in the plume of PPTs with coaxial electrodes [40]. This is due to the non-symmetric geometry of parallel electrodes, while coaxial electrodes are obviously axially symmetric.…”

Section: Formation Mechanism Analysis Of the Asymmetric Plume Structurementioning

confidence: 98%

Time-resolved investigation of the asymmetric plasma plume in a pulsed plasma thruster

Zhang¹,

Zhang²,

Ling³

et al. 2020

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Electric propulsion (EP) has become one of the most promising options for the motion control of small satellites. The physics behind the ejected plasma plumes of EP thrusters has attracted significant interest due to their interactions with the critical components of satellites. Axisymmetric plume assumptions are widely used in simulations and plume diagnostics. However, we show here that the plasma plume of a parallel-plate pulsed plasma thruster (PPT) is asymmetrically distributed along the centerline of the electrodes, contrary to the inherent axisymmetric assumption. To study this asymmetric plume structure in depth, a triple Langmuir probe was used to obtain the electron density of a two-dimensional plume area over the operating period of a PPT. The electron density results show that the plasma forms an 'I' shape plume at 2 µs after the initial main discharge. However, over time, the plume appears to cant significantly towards the cathode. The physical mechanism behind the asymmetric plume structure is studied through inter-electrode magnetic probe measurements and plasma trajectory analyses. The successive magnetic profiles indicate that the plasma is accelerated by a non-symmetrical electromagnetic force between the electrodes, which results in the plasma exhausting out with an entirely asymmetric distribution shifted upwards towards the cathode. This was also verified using varying sets of discharge voltage experiments. This work also indicates that care must be taken in the selection of the measurement points in PPT plume diagnostics. The measurement points should be chosen above the centerline of the PPT exit as the plasma parameters along the centerline may not be the most energetic part as previously believed. Furthermore, the asymmetric acceleration component of the electromagnetic force between the electrodes can enlighten us in the design of electromagnetic field configurations for future discharge channel optimization.

show abstract

Plume Characterization of Electric Solid Propellant Pulsed Microthrusters

Cited by 30 publications

References 24 publications

In-plume acceleration of leading-edge ions from a pulsed plasma thruster

In-plume acceleration of leading-edge ions from a pulsed plasma thruster

Observation of Late-Time Ablation in Electric Solid Propellant Pulsed Microthrusters

Time-resolved investigation of the asymmetric plasma plume in a pulsed plasma thruster

Contact Info

Product

Resources

About