The Applicability of Dual Stage Ion Optics to Ion Engines for High Power Missions

In this paper, the applicability of dual stage ion optics and in particular of the so-called dual stage ion engine to high power, high specific impulse missions will be evaluated. First, the performance limits of conventional two gridded ion engines (GIE) will be discussed and the advantages provided by dual stage ion engines reported. The limits of applicability of a dual stage ion engine will be analyzed analytically and the results confirmed numerically. The lifetime and performance of a three gridded dual stage ion engine (DS3G) will be numerically investigated and compared to those of a conventional GIE assessing for the first time in the open literature under what condition dual stage ion optics provide performance improvements over conventional GIEs and what is its impact on the thruster lifetime. Dual stage ion engines have been found to be capable of providing higher thrust density and longer lifetime with respect to conventional gridded ion engines.