Doubly charged ion effect on life prediction accuracy of ion acceleration grid system

Ion engines offer substantial weight savings but produce very little thrust. To meet mission requirements they must therefore be operational for extensive periods of time. Until now, all ion engines used in space missions have required expensive and time-consuming ground-based life qualification tests prior to flight. These tests can be shortened using the numerical simulation code “JIEDI” (JAXA Ion Engine Development Initiatives), which is now reaching the level of a practical engineering application. However, doubly charged ions are not fully modeled in JIEDI code. In the present study, the effect of doubly charged ions has been investigated to improve the life prediction accuracy of ion acceleration grid simulations. Findings show that the grid erosion increases with an increasing doubly charged ion fraction under the same propellant flow rate and the same beam current condition, which suggests that the doubly charged ion fraction is a crucial factor in life prediction accuracy.