Luckily, my friend remembered the old Sharper Image Ion fan infomercials wherein they actually did a pretty good job explaining the science. Those fans have an

Luckily, my friend remembered the old Sharper Image Ion fan infomercials wherein they actually did a pretty good job explaining the science. Those fans have an anode array that gives the air a positive charge, and then large cathode blades that attract the charged air. Because of fluid dynamics, the air accelerates past the blades and keeps on going out the back. Ion thrusters use the same general principle, but they need to carry their own source of ions into space. Most use tanks of compressed noble gas, but Neumann's new design turns solids into gas as part of the ionization process. This is great because noble gas containers are heavy for space applications, and the gasses themselves can be scarce and expensive.