A simple analysis of spacecraft charging involving blocked photoelectron currents

Besse, Arthur L.; Rubin, A. G.

doi:10.1029/ja085ia05p02324

Cited by 31 publications

(22 citation statements)

References 13 publications

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“…When the escaping photoelectrons are suppressed, current balance can be achieved, and charging to high negative values can occur. 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].…”

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confidence: 99%

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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confidence: 99%

Aspects of Spacecraft Charging in Sunlight

Lai

Tautz

2006

IEEE Trans. Plasma Sci.

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“…where we define A = -Al > 0 (our notation agrees with a previous treatment [Besse and Rubin, 1980]; if Al were > 0, then the Sun would be at 180 degrees instead of at 0). In the same way, for the MQ model, we get…”

Section: Comparison Of the MD And Mq Charging Modelsmentioning

confidence: 78%

“…The first model, MD, where the satelUte may be non-rotating, has been treated by Besse and Rubin [1980] and others [Mandell, etal, 1978;Higgins, 1979].…”

Section: Introductionmentioning

confidence: 99%

Analytic Models for Sunlight Charging of a Rapidly Spinning Satellite

Tautz¹

2003

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“…We first look at the zero spin limit. It is known that the solution is a monopole-dipole system (Besse and Rubin, 1980) pointing in the sun direction, X , and given by…”

Section: Description Of the Modelsmentioning

confidence: 99%

“…The potentials are expanded in a series of multipoles and we consider the three lowest order terms: the monopole, dipole, and the quadrupole. The monopole-dipole model, where the satellite is non-rotating, has been treated by Besse and Rubin (1980), Mandell et al (1978), and Higgins (1978). The monopole-quadrupole system has been treated by Tautz (2003).…”

Section: Introductionmentioning

confidence: 99%

Analytic models for a spherical satellite charging in sunlight at any spin rate

Tautz¹,

Lai

2006

Ann. Geophys.

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Abstract. We present analytic models for the steady state potential distributions surrounding a spinning, dielectriccoated, spherical spacecraft charging in sunlight. The sun direction is assumed to lie in the satellite bellyband plane, perpendicular to the spin axes. The models are based on a multipole expansion of Laplacian potentials external to the spacecraft surface. The combination of monopole potentials along with the dipole or quadrupole contributions produce potential barriers which form at the satellite surface. These barriers can block escaping photoelectrons and lead to current balance, allowing sunlight charging to high negative levels. In a previous treatment, analytic models were limited to fast spin relative to differential charging rates so that the solutions had azimuthal symmetry around the spin axes. By introducing an associated Legendre term into the potential expansion, the azimuthal symmetry is removed, and the models can be developed to encompass any spin rate. The analysis turns up three functions of spin rate which are only known at the spin limits, but the characteristics of the charging of a rotating sphere can be explored using approximate forms which represent the basic trends. For finite spin, the sunlit side charges less (negatively) than the shade side which is in contrast to the fast spin case, where these two potentials are equal. Also, for finite spin, differential charging develops perpendicular to the sun and spin axis directions, due to the transverse motion. This transverse charging occurs at all finite spin rates, disappearing only at the zero and infinite spin limits. There is a correlated lag angle between the direction of maximum sheath radius and the sun line. Plots are given to illustrate the potential distributions representing barrier dominated sunlight charging of a spinning dielectric coated spherical satellite.

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A simple analysis of spacecraft charging involving blocked photoelectron currents

Cited by 31 publications

References 13 publications

Aspects of Spacecraft Charging in Sunlight

Aspects of Spacecraft Charging in Sunlight

Analytic Models for Sunlight Charging of a Rapidly Spinning Satellite

Analytic models for a spherical satellite charging in sunlight at any spin rate

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