The Xenon Ion Propulsion System reference article from the English Wikipedia on 24-Apr-2004
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Xenon Ion Propulsion System

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XIPS - A mehtod of electrical propulsion where Xe+ ions (xenon atoms with one electron removed) are accelerated electrostatically through an electric field to velocities of about 30 km/s. There is a positive grid with an electric potential of +1090 V and a negative grid with an electric potential of -225 V.