Within NASA's Project Prometheus, high specific impulse ion thrusters for electric propulsion of spacecraft for the proposed Jupiter Icy Moon Orbiter (JIMO) mission to three of Jupiter's moons: Callisto, Ganymede and Europa will require high voltage operation to meet mission propulsion. The anticipated approx.6,500 volt net ion energy will require electrical insulation and propellant isolation which must exceed that used successfully by the NASA Solar Electric Propulsion Techlogy Readiness (NSTAR) Deep Space 1 mission thruster by a factor of approx.6. Xen propellant isolator prototypes that operate at near one atmosphere and prototypes that operate at low pressures (