Ion engines still use propellant, they dont just create momentum. Your link even mentions as much, pointing out that they use inert gases as their propellant. They merely use a lot less propellant than chemical rockets by accelerating that propellant to higher speeds.
There’s an ion engine that does just that. Unfortunately thrust is very low.
Ion engines still use propellant, they dont just create momentum. Your link even mentions as much, pointing out that they use inert gases as their propellant. They merely use a lot less propellant than chemical rockets by accelerating that propellant to higher speeds.