Analytic models for a rapidly spinning spherical satellite charging in sunlight

Tautz, M. F.

doi:10.1029/2004ja010787

Cited by 18 publications

(19 citation statements)

References 19 publications

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“…• , we find an approximate Sun/shade potential ratio χ(A, θ) that goes between the two aforementioned cases [27]. Although there are differences in details, the basic mechanism is the same: The shaded side charges, and the fields wrap around to form a potential barrier that acts to suppress the photoemission.…”

Section: Multipole Modelsmentioning

confidence: 99%

“…2, data are shown of spacecraft potential versus electron temperature [27]. The upper data branch represents charging in eclipse, and the lower data branch is for daylight charging.…”

Section: Onset Of Spacecraft Charging In Sunlightmentioning

confidence: 99%

“…• , a dominant monopole-quadrupole potential distribution occurs [27]. The potential then has the following form:…”

Section: Multipole Modelsmentioning

confidence: 99%

“…We now assume that the satellite is spinning fast around the Z-axis and that the Sun's direction lies somewhere in the bellyband plane. The value of V M = K(1 − Q/2) [27] at the fast spin limit [see Fig. 1(b)].…”

Section: Relation Between Satellite Surface Node Potentialsmentioning

confidence: 99%

“…The simplest type of differential charging based on blocked photoelectrons is in the monopole-dipole form [14], [15], [24]- [26]. With a fast spinning satellite, a monopole-quadrupole form is possible [27]. Multipole models are discussed in Sections II-IV.…”

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confidence: 99%

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Aspects of Spacecraft Charging in Sunlight

Lai

Tautz

2006

IEEE Trans. Plasma Sci.

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Abstract-This paper is an overview of spacecraft charging in sunlight. The daylight photoelectron flux emitted from spacecraft surfaces normally exceeds the ambient electron flux. As a result, charging of spacecraft surfaces to positive voltage is expected to occur in sunlight. Indeed, spacecraft are often observed to charge to low positive voltages in sunlight. However, spacecraft can charge to high-level (kiloelectronvolts) negative voltages in sunlight. Why do spacecraft charge negatively in sunlight? One chief reason concerns differential charging between the sunlit and dark sides. For a satellite with dielectric surfaces, an electric field builds up on the shaded surfaces and then wraps around to the sunlit side to form a potential barrier that suppresses the photoemission. A monopole-dipole (for zero spin) or monopole-quadrupole model (for fast spin) describes the differential charging potential distribution due to blocked photoelectrons. It is shown that these cases are similar to a more general multipole potential field in that the surface node potentials satisfy an approximate linear relation. These cases are all driven by the shade side charging so that the onset for charging is approximately the same in sunlight or eclipse if conduction currents through the spacecraft can be neglected. If conduction currents are important, potential barriers can develop on the dark side, leading to suppression of the secondary emission currents and modification of charging onset. The results were briefly compared with observations. Another important reason for negative charging concerns reflectance. Highly reflective mirrors generate substantially reduced photoemission so that current balance can be achieved without barrier formation. The onset for charging in this case depends strongly on the reflectivity. The critical temperature for charging of surface materials under space substorm conditions with different ratios of photoemission current to electron ambient current, corresponding to varying satellite surface reflectivity values, was calculated. Numerical results, which show that with substantially reduced photoemission, highly reflective surfaces charge in sunlight with the critical temperature for onset decreasing with increasing reflectivity, are presented.

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Section: Multipole Modelsmentioning

confidence: 99%

“…2, data are shown of spacecraft potential versus electron temperature [27]. The upper data branch represents charging in eclipse, and the lower data branch is for daylight charging.…”

Section: Onset Of Spacecraft Charging In Sunlightmentioning

confidence: 99%

“…• , a dominant monopole-quadrupole potential distribution occurs [27]. The potential then has the following form:…”

Section: Multipole Modelsmentioning

confidence: 99%

Section: Relation Between Satellite Surface Node Potentialsmentioning

confidence: 99%

mentioning

confidence: 99%

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Aspects of Spacecraft Charging in Sunlight

Lai

Tautz

2006

IEEE Trans. Plasma Sci.

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Charging of fast spinning spheroidal satellites in sunlight

Tautz

Lai

2007

Journal of Applied Physics

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We present models for a fast spinning, dielectric coated, spheroidal ͑prolate or oblate͒ spacecraft charging in sunlight. This work is a generalization of previous treatments of sunlight charging of spherical satellites. The main difference is that the spacecraft geometry can be characterized by a shape parameter that sets the aspect ratio of the spheroids. The models are based on an expansion of the Laplacian potentials external to the spacecraft surface in terms of products of standard Legendre polynomials, describing the polar angle dependence, and modified Legendre functions of the second kind, representing the "radial" behavior. The potential distributions are discussed relative to the corresponding monopole-dipole and monopole-quadrupole configurations in spherical geometry. A Taylor expansion is developed for the potentials when the shape parameter is large ͑the spherical limit͒ and expressions are also given in the opposite limit, when the shape parameter goes to zero. As in the spherical case, the potentials produce photosheath barriers which act to block escaping photoelectrons and lead to current balance, allowing sunlight charging to high negative levels. The sheath barrier location and height are calculated numerically, for a wide range of shape parameters. Contour plots are given to depict the potential distributions for sunlight charging of prolate and oblate spheroids at a representative aspect ratio.

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Some Novel Ideas of Spacecraft Charging Mitigation

Lai

2012

IEEE Trans. Plasma Sci.

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Analytic models for a rapidly spinning spherical satellite charging in sunlight

Cited by 18 publications

References 19 publications

Aspects of Spacecraft Charging in Sunlight

Aspects of Spacecraft Charging in Sunlight

Charging of fast spinning spheroidal satellites in sunlight

Some Novel Ideas of Spacecraft Charging Mitigation

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