Our system can use any solid, conductive material as a propellant since the arc cathode is the propellant. This differentiates it from pulsed plasma thrusters which strike an arc across the surface of a polymer propellant rod, rather than striking the arc from the surface of a conductive cathode.
The physical properties of metals lend themselves well to spacecraft propellant storage, as most metals are inherently safe in the vacuum and radiation environment of space. This removes the need for propellant stowage systems such as tanks, the mass of which can be devoted to more payload. Similarly, the greater density of other propellant metals reduces volume, freeing up space for other systems.