Effects of evolving surface contamination on spacecraft charging

Chang, W. Y.; Dennison, JR; Kite, Jason; Davies, R. E.

doi:10.2514/6.2000-868

Cited by 22 publications

(22 citation statements)

References 28 publications

(38 reference statements)

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“…Electron emission measurements are performed in an ultra-high vacuum chamber (base pressure < 10 -9 Torr) to minimize surface contamination that can substantially affect emission properties [24], [25]. Electron sources provide electron energy ranges from ~50 eV to ~30 keV and incident electron currents (1-100 nA) with pulsing capabilities ranging from 10 ns to continuous emission [8]- [10].…”

Section: A Instrumentation and Methodsmentioning

confidence: 99%

Low-Fluence Electron Yields of Highly Insulating Materials

Hoffmann

Dennison

Thomson

et al. 2008

IEEE Trans. Plasma Sci.

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Abstract-Electron-induced electron yields of high-resistivity, high-yield materials -ceramic polycrystalline aluminum oxide and the polymer polyimide (Kapton HN), -were made by using a low-fluence, pulsed incident electron beam and charge neutralization electron source to minimize charge accumulation. Large changes in energy-dependent total yield curves and yield decay curves were observed, even for incident electron fluences of <3 fC/mm 2 . The evolution of the electron yield as charge accumulates in the material is modeled in terms of electron recapture based on an extended Chung-Everhart model of the electron emission spectrum. This model is used to explain anomalies measured in highly insulating, high-yield materials, and to provide a method for determining the limiting yield spectra of uncharged dielectrics. Relevance of these results to spacecraft charging is also discussed.

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Section: A Instrumentation and Methodsmentioning

confidence: 99%

Low-Fluence Electron Yields of Highly Insulating Materials

Hoffmann

Dennison

Thomson

et al. 2008

IEEE Trans. Plasma Sci.

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“…Fitting functions are described in. [7][8][9][10][11] Fitting parameters are listed in Table I. (b) Electron emission spectra as a function of emission energy.…”

Section: Causes Of Threshold Chargingmentioning

confidence: 99%

“…13 and 14. Fits are shown for a two parameter fit used in NASCAP 10 and a six parameter extended fit. 8,11 Fitting parameters are listed in Table I. (d) Photon-induced electron yield curves as a function of incident photon energy.…”

Section: Causes Of Threshold Chargingmentioning

confidence: 99%

“…By contrast, if η δ + >1, no scaling of Ń e (E e ) can lead to negative charging. 11 In this case, increases in the electron plasma density typically lead to only minimal increases in positive surface bias, as a result of the self-regulating nature of positive biasing. 19 Similar effects can occur if the magnitude or the shape of Ń Ion (E Ion ) or Ń Ph (E Ph ) are changed relative to Ń e (E e ).…”

Section: A Changes Of the Space Plasma Environmentmentioning

confidence: 99%

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Triggering Threshold Spacecraft Charging with Changes in Electron Emission from Materials

Dennison

Hoffmann

Abbott

2007

45th AIAA Aerospace Sciences Meeting and Exhibit

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Modest changes in spacecraft charging conditions can lead to abrupt changes in the spacecraft equilibrium, from small positive potentials to large negative potentials relative to the space plasma; this phenomenon is referred to as threshold charging. It is well known that temporal changes of the space plasma environment (electron plasma temperature or density) can cause threshold charging. Threshold charging can also result from by temporal changes in the juxtaposition of the spacecraft to the environment, including spacecraft orbit, orientation, and geometry. This study focuses on the effects of possible changes in electron emission properties of representative spacecraft materials. It is found that for electron-induced emission, the possible threshold scenarios are very rich, since this type of electron emission can cause either positive or negative charging. Alternately, modification of photon-or ion-induced electron emission is found to induce threshold charging only in certain favorable cases. Changes of emission properties discussed include modifications due to: contamination, degradation and roughening of surfaces and layered materials; biasing and charge accumulation; bandstructure occupation and density of states caused by heat, optical or particle radiation; optical reflectivity and absorptivity; and inaccuracies and errors in measurements and parameterization of materials properties. An established method is used here to quantitatively gauge the relative extent to which these various changes in electron emission alter a spacecraft's charging behavior and possibly lead to threshold charging. The absolute charging behavior of a hypothetical flat, twodimensional satellite panel of a single material (either polycrystalline conductor Au or the polymeric polyimide Kapton™ H) is modeled as it undergoes modification and concomitant changes in spacecraft charging in three representative geosynchronous orbit environments, from full sunlight to full shade (eclipse) are considered.

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“…Secondary yields is strongly dependent on the state of the material surface, which can be significantly modified due to outgassing and deposition of contaminants on the surface. 17,18 It was found that surface deposition of contaminants lead to significant decrease of γ, which reaches 50% for aluminum electrode. 17 According to Eq.…”

Section: Outgassing Induced Breakdown and Modelsmentioning

confidence: 99%

High voltage breakdown induced by outgassing of space materials

et al. 2015

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Increasing demand for higher voltage and power levels aboard spacecrafts requires space vacuum as insulator. A concerned issue for this is whether the outgassing of dielectric materials profusely used in spacecrafts can induce breakdown, and what, if it occurs, the mechanism and characteristics are. In this paper, low pressure breakdown induced by outgassing was investigated experimentally. It’s found that vacuum breakdown is significantly facilitated by the outgassing of dielectric materials. Measurements of Paschen’s curves for typical outgassing samples show that significant decrease of breakdown voltage occurs in high vacuum region due to increase of local pressure from outgassed products. Another important mechanism that affects the breakdown voltage is the electrode surface contamination by the outgassed components. Primary models with these mechanisms taken into account are described and the model calculations agree well with the measurements. Both experimental findings and theoretical analysis indicate that outgassing of space materials is a potentially important threat to high voltage systems with vacuum as insulation.

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Effects of evolving surface contamination on spacecraft charging

Cited by 22 publications

References 28 publications

Low-Fluence Electron Yields of Highly Insulating Materials

Low-Fluence Electron Yields of Highly Insulating Materials

Triggering Threshold Spacecraft Charging with Changes in Electron Emission from Materials

High voltage breakdown induced by outgassing of space materials

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