Impact of nonideal effects on bare electrodynamic tether performance

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American Institute of Aeronautics and Astronautics (AIAA)
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The paper deals with three nonideal effects, often neglected in the literature, which affect the current and potential profiles along a bare electrodynamic tether. The first appears when the size of the tether cross-section width is large enough to have potential barriers for the probe radius in the radial effective potential energy of the plasma electrons. The tether is not able to capture the orbital-motion-limited current law and is said to operate beyond the orbital-motion-limited regime. It is shown that this effect can be accurately modeled by just scaling the tether characteristic length according to a dimensionless factor depending on tether and plasma properties. The high-bias approximation in the orbital-motion-limited current collection law, normally assumed in past work, is discussed. The third effect becomes relevant when the cathodic plasma contactor potential drop is nonnegligible compared with the product of the tether length and the motional electric field. Numerical simulations performed with a newly developed tether flight simulator across a wide range of mission scenarios and design parameters shows that the first effect can be safely ignored for preliminary tether mission design. The cathodic plasma contactor potential drop, however, increases the deorbit time of kilometer-length tethers in a nonnegligible way. In the extreme case in which the tether is less than a few hundred meters long, such an effect would strongly deteriorate its deorbit performance.
Tether, Bare electrodynamic, Nonideal effects
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Journal of propulsion and power, 31(3), pp. 951-955