Publication: An electric model for bare-photovoltaic tethers in the passive mode
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2023-11-08
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Elsevier Ltd on behalf of IAA
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Abstract
A bare-photovoltaic tether (BPT) is a long conductive tape in orbit that provides propellant-less propulsion and power harvesting. An electric model for a BPT operating in the passive mode and composed of a bare segment and a bare-photovoltaic (bare-pv) segment coated with thin-film solar cells on one side is presented. The pv cells, which are electrically insulated from the conductive substrate, are connected to two electric busbars that also serve as electrical contacts to the spacecraft. The power harvested by the cells can be used by the spacecraft or, as considered in this work, to boost tether performance. The electric model takes into account that, depending on the number and location of zero-bias points, four regimes of operation exist for this type of BPT. Current and voltage profiles solutions that are not possible for standard bare tethers are presented. A parametric analysis of the operation regimes varying the tether length, the length of the pv segment, and the power was carried out. Two complementary methods to find the optimum length of the bare-pv segment for a given total tether length and mission are presented. The first method is based on the optimization of the normalized average current, which controls the strength of the Lorentz force and measures tether efficiency and the second method uses as figure of merit the deorbit time in postmission disposal scenarios. For both of them it is shown that an optimum exists for the length of the pv segment. An enhancement in performance above 30% as compared with standard bare tethers was found for the considered scenario.
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Keywords
Electrodynamic tether, Space debris, Electric propulsión, Bare-photovoltaic, Thin film solar cells
Bibliographic citation
Acta Astronautica, 214, 609-618.