Unstable potential of geosynchronous spacecraft

Sudden onsets of high‐voltage differential charging on spacecraft in an ambient environment may affect operations and the survival of on‐board electronics. Triple‐root jumps may be very sudden. We discuss two aspects, one theoretical and one observational. By using current balance, the theoretical parametric domain in which triple‐root jumps may occur for a surface material in a double Maxwellian electron environment has been calculated. The relation between the domain and the “critical” or “threshold” temperature for a material is revealed. We present an example of the prediction of the occurrence of a triple‐root spacecraft potential jump in a time‐varying space environment.

Section: The Role Of Critical Temperaturementioning

confidence: 99%

mentioning

confidence: 99%

Theory and observation of triple‐root jump in spacecraft charging

Lai¹

1991

“…In this paper we shall examine another type of differential charging due to the fact that in non-Maxwellian plasmas certain material may have double-valued potentials [Prokopenko and Laframboise, 1980;Sanders and lnouye, 1978;Besse, 1981]. This implies that adjacent isolated surfaces made of the same material may follow different charging histories and end up on different solutions of the current balance condition.…”

Section: Introductionmentioning

confidence: 99%

The use of electrostatic noise to control high‐voltage differential charging of spacecraft

Hastings¹

1986

High differential charging is known to occur on geostationary satellites between two electrically isolated pieces of the same material. This happens because current balance with the ambient space environment on each surface can be satisfied by different surface potentials. Three such potentials (two stable and one unstable) are found for the two-Maxwellian plasmas considered in this study and in the absence of photoelectron emission. Thus two isolated surfaces can have significantly different potentials leading, possibly, to electrostatic discharges. It is shown that, in an electrostatically noisy environment, one of the surface potentials is more likely to occur than the others and thus both surfaces will achieve this most probable potential independent of their previous charging history. The time for this to happen, while dependent on the characteristics of the roots, can be relatively short and may limit this type of differential charging. This effect is examined in quantitative detail for the environments measured by the ATS-5 and SCATHA satellites.

“…The zero current points at -18 V and +3100 V correspond to stable equilibria. The zero current point at 17 V is unstable; if secondary electrons can escape, a surface that starts at a voltage below 17 V will go toward -18 V; a surface that starts above 17 V will go towards +3100 V. (The existence of multiple roots has been discussed previously by several authors [Prøkopenko and Lafrarnboise, 1977;Besse, 1981] for non-Maxwellian spectra.) However, as we saw in the positive ground calculations, the highest possible positive voltage equilibrium point is frequently not achieved because as the Surface voltage nears that of the underlying ground, the direction of the surface electric field changes sign, suppressing the secondary electron emission.…”

Section: Solar Cell 'Snapover'mentioning

confidence: 89%

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

Katz¹,

Mandell²

1982

A theory is presented for the steady‐state potential of insulated surfaces near exposed high voltages. The term ‘insulated surfaces’ is used to mean either dielectric surfaces or electrically isolated metallic surfaces. The potential is bounded below by the zero of the material's I‐V curve assuming total suppression of secondary electrons, and above by assuming total extraction of secondaries. Within these bounds, the material's surface potential is determined consistently with the solution to Poisson's equation external to the vehicle. The theory is compared with rocket experiments and with SCATHA satellite data. Also, an explanation is suggested for the observed ‘snapover’ of solar cell coverslips from near plasma ground potential to near the potential of positively biased interconnects with increasing bias voltage.