RAE/Culham T4 Ten Centimeter Electron-Bombardment Mercury Ion Thruster

The RAE/Culham T4 thruster is described with particular reference to its suitability for N-S stationkeeping on planned European communication satellites and for many other possible missions. Details are given of the design, construction, testing, and performance, including the characteristics and life test experience of components such as vaporizers, isolators, and grids. The accuracy of the physically-based scaling laws used in the design is demonstrated. Special reference is made to the excellent thermal stability and performance of the grid system, to efforts made to minimize grid erosion, and to the flexibility offered by a large throttling range.