Test facilities for high-power electric propulsion

Sovey, James S.; Vetrone, R.; Grisnik, Stanley P.; Myers, Roger; Parkes, James E.

doi:10.2514/3.23706

Cited by 15 publications

(9 citation statements)

References 13 publications

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“…The very low pressures obtained when testing electric thrusters are maintained using cryogenic pumps that employ gaseous helium. In such experiments, propellant frost will build up on cryopump surfaces and eventually will limit the pumping speed 5 ; hence, even though the nominal sticking coefficient for gas-steel pump plates is high, in operation the pump sticking coefficient may be much lower. Vacuum pump area has an important effect as well.…”

Section: Nomenclature Dmentioning

confidence: 99%

Rarefied Background Flow in a Vacuum Chamber Equipped with One-Sided Pumps

Cai

Boyd

Sun

2006

Journal of Thermophysics and Heat Transfer

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Spacecraft propulsion systems, such as Hall thrusters, are designed and tested in large vacuum chambers. The pumping capacity of modern facilities makes it possible to maintain pressures as low as 10 − −3-10 − −4 Pa with thrusters in operation. For these vacuum chambers, a fundamental concern is the facility effects on the chamber performance. Several free molecular models are proposed to analyze the rarefied background flow inside a vacuum chamber equipped with one-sided vacuum pumps located at one chamber end. These models lead to various sets of analytical expressions linking several facility effects, such as pump sticking coefficient, pump area, and wall effects. These expressions can be used to estimate the pump sticking coefficient, to evaluate performance of vacuum chambers, and to aid constructing proper background flow for particle simulations. About 70 numerical simulations of background flows inside a vacuum chamber validate these models. These numerical simulations and analytical results indicate that these models are capable of predicting average background pressure and flow velocities. Depending on specific parameters, the background flow can have a significant nonzero mean velocity and cannot be considered to follow a Maxwellian velocity distribution.

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Section: Nomenclature Dmentioning

confidence: 99%

Rarefied Background Flow in a Vacuum Chamber Equipped with One-Sided Pumps

Cai

Boyd

Sun

2006

Journal of Thermophysics and Heat Transfer

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“…If the net erosion rate was determined to be negative, the net deposition rate was determined instead. This was determined by subtracting the erosion rate using Equation 3 and jm from the deposition rate in Equation 10. In this manner, the deposition rate from each source was determined.…”

Section: Net Erosion/deposition Ratementioning

confidence: 99%

“…Deposition of thruster contamination products on a solid surface from a particular source can be determined by the following equation: (10) The contamination sticking coefficient has been set equal to 1 in this equation. 17 The index m refers to different sources of thruster contamination (from the exterior pole, exterior insulator, and interior insulator respectively).…”

Section: Contamination Deposition Modelmentioning

confidence: 99%

See 1 more Smart Citation

End-of-life Stationary Plasma Thruster far-field plume characterization

Pencil

Randolph²,

Manzella³

1996

32nd Joint Propulsion Conference and Exhibit

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“…4,5 For vacuum chambers used for EP experiments, large cryogenic pumps are usually equipped as the primary pumps. There are several facility effects that have significant impact on the vacuum chamber backpressure.…”

Section: Introductionmentioning

confidence: 99%

Free molecular background flow in a vacuum chamber equipped with two-sided pumps

Cai

Boyd

Sun

2005

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Spacecraft propulsion systems, such as Hall thrusters, are designed and tested in large vacuum chambers. The pumping capacity of modern facilities makes it possible to maintain pressures as low as 10 −3 -10 −4 Pa. One fundamental concern for the vacuum chamber is the facility effects on the chamber performance. In this study, several free molecular models are developed to analyze the rarefied background flow inside a vacuum chamber equipped with two-sided vacuum pumps. These models lead to various sets of analytical results including velocity distribution functions for the background flow and formulas to compute the vacuum pump sticking coefficient. These results can be used to evaluate the performance of vacuum chambers and to aid constructing proper background flows for particle simulations of these systems. The results indicate that the background flow conditions can have a significant nonzero mean velocity and cannot be considered to be described by a Maxwellian velocity distribution. The models are applied to analyze the rarefied background flow in a specific vacuum chamber. Calculations of the sticking coefficient for flow of xenon in the vacuum chamber yield values close to 0.40 for cryogenic pumps. Several modifications of the background flow treatment for particle simulations are proposed with the aid of these analytical results.

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Test facilities for high-power electric propulsion

Cited by 15 publications

References 13 publications

Rarefied Background Flow in a Vacuum Chamber Equipped with One-Sided Pumps

Rarefied Background Flow in a Vacuum Chamber Equipped with One-Sided Pumps

End-of-life Stationary Plasma Thruster far-field plume characterization

Free molecular background flow in a vacuum chamber equipped with two-sided pumps

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