In the proposed Phase II program, Busek Co. will demonstrate an innovative methodology for clustering Hall thrusters into a high performance, very high power propulsion system. To fulfill the full range of Hall thruster power requirements (100 kW ? 1 MW) envisioned by NASA for orbit insertion, planetary transfers and manned exploration, rather than developing a >500kW system with one or two large thrusters there are clear advantages to reach the very high power by clustering multiple thrusters of lower power. In the Phase I program, Busek demonstrated a shared magnetics clustering concept that combined the benefits of simple clustering with additional advantages such as the mass savings and power loss reduction of a shared magnetic structure. In Phase II, Busek will demonstrate an alternative shared magnetics concept of clustering and design, fabricate and test a sub-scale nested thruster. The nested thruster consists of two concentric discharge cavities that share a portion of the magnetic structure. Busek will also continue to investigate the shared magnetics concept of the Phase I program and merge the nested concept into the shared magnetics cluster architecture. Busek is uniquely positioned to implement the proposed program having expertise in both the clustering of Hall thrusters and shared magnetics thruster development.