Differential charging of high:Voltage spacecraft: The equilibrium potential of insulated surfaces

Katz, Ira; Mandell, M. J.

doi:10.1029/ja087ia06p04533

Cited by 18 publications

(6 citation statements)

References 21 publications

(20 reference statements)

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“…A good review of the work is given by Whipple [1981]. Intensive numerical simulations have been done by Laframboise et al [1982] and by Katz and Mandell [1982], and we have taken portions of the CYLVIA code of Laframboise et al [1982] in this work. However, the mathematical modeling of the spacecraft charging is more complex, since it involves unknown boundary conditions at the spacecraft surface.…”

Section: Introductionmentioning

confidence: 99%

Influence of nonuniform surface potential on the measurement of plasma parameters by electrostatic probes

Godard¹,

Berthelier²

1989

J. Geophys. Res.

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In the theory of electrostatic probes, it is usually assumed that the probe surface potential is uniform. However, nonuniformity of the surface work function produces a nonuniformity in surface potential which may modify the current collection. This effect is examined for an infinite cylinder immersed in a collisionless plasma in the limit when Debye length is much greater than probe radius, by numerically following charged‐particle orbits in a Laplace potential. It is shown that only large‐scale, macroscopic potential nonuniformities are important for the current collection, and that microscopic nonuniformities are smoothed over relatively short distance by the Laplace equation character of the potential.

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Section: Introductionmentioning

confidence: 99%

Influence of nonuniform surface potential on the measurement of plasma parameters by electrostatic probes

Godard¹,

Berthelier²

1989

J. Geophys. Res.

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“…These satellites experienced potentials of several kilovolts (negative) in eclipse and several hundreds of volts negative in sunlight. Each of these had exposed insulating areas, and differential charging has been experimentally inferred for all of them [Katz andMandell, 1982' Olsen andPurvis, 1983]. On the other hand, spacecraft with only grounded conducting exposed surfaces, such as…”

Section: Introductionmentioning

confidence: 99%

An unusual charging event on ISEE 1

Olsen

Whipple²

1988

J. Geophys. Res.

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Electrostatic cleanliness requirements on ISEE 1 were expected to prevent negative charging in sunlight. This has largely been true, but on three occasions, ISEE 1 has been observed to charge to significant negative potentials in sunlight. Data from the two electric field experiments and from the plasma composition experiment on ISEE 1 show that the spacecraft charged to close to -70 V in sunlight at about 0700 UT on March 17, 1978. Data from the electron spectrometer experiment show that there was a potential barrier of some -10 to -20 V about the spacecraft during this event. The potential barrier was effective in turning back emitted photoelectrons to the spacecraft. Potential barriers can be formed by differential charging on the spacecraft or by the presence of excess space charge in the plasma. The shape of the barrier suggests that it is due to the former, even though electrostatic cleanliness specifications imposed on ISEE were intended to eliminate differential charging. Modeling of this event showed that the barrier could not be produced by the presence of space charge but that it was most likely produced by differential charging of the solar arrays. ISEE and GEOS, have experienced. much smaller potentials, e.g., +1 to +50 for ISEE in sunlight and +1 to +10 for GEOS in sunlight [Wrenn, 1979' Wrenn et al., 1979Whipple, 1981]. The electrostatic specifications for ISEE required that no exposed components (with some exceptions) charge to potentials in excess of 1 V with respect to the spacecraft ground. Also, all components exposed to the, plasma environment were to be "sufficien•tly conducting" and be connected to the spacecraft ground through low impedance paths.In spite of these electrostatic cleanliness requirements and ß general success in controlling negative charging, there have been indications of significant charging events on ISEE 1, with the spacecraft reaching a negative potential of the order of -100 V in sunlight. These indications initially came from ion data obtained by the plasma composition experiment which showed that low-energy (thermal) ions had been accelerated to kinetic energies of the order of 100 eV before they were detected by the instrument (E. Shelley, private communication, 1982). It is important to understand such charging events, if they are indeed real, in order to be able to evaluate the effectiveness of the electrostatic cleanliness specifications. For example, the charging of electrostatically "dirty" spacecraft such as ATS 5, ATS 6, and SCATHA has been shown to be very dependent on differential charging effects [Olsen et al., 1981' Olsen and Purvis, 1983]. The purpose of this paper is to examine in detail a sunlight cha•ging event on ISEE 1 and to determine if differential charging occurred in spite of the electrostatic cleanliness requirements. 5568

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“…All the surfaces then charge negative at a rate corresponding with differential charging, typically a few hundred volts per minute. Sunlight charging is a multi dimensional effect calculable only by models, such as NASCAP and POLAR, which solve Poisson's equation in three dimensions 14 .…”

Section: 0mentioning

confidence: 99%