Discharge and ion beam optimization of an advanced annular ion engine*

The annular ion engine is a new type of gridded ion thruster featuring a central ion optics support.  The central support allows the engine to accommodate larger ion optics and thus operate at higher power, thereby circumventing the span to gap limitations of conventional ion engines.  The architecture is inherently scalable in power.  The geometry also provides additional magnetic collection area for electrons thereby increasing the engine’s capacity to  accommodate much larger discharge currents before the onset of convective instabilities.   In contrast to conventional ion engines, the discharge cathode is not located on axis and thus discharge uniformity relies on drifts defined by the magnetic circuit and local electric field.  Presented here is the use of a  3-D magnetosolver code in conjunction with a plasma 0-D model aimed at optimizing discharge performance to minimize discharge losses. The design and implementation of an advanced graphite ion optics set is also discussed.