I'm looking for some information on what the fuel/propellant mass per kg of payload is for ion drives. Hall X3 or VASIMR or whichever is currently the 'best' that we have available.
This isn't for any specific 'mission', though I know distance is an important factor. Kg of fuel per Kg of payload per AU would be my ideal response, if there's a relatively straightforward way of calculating this?
All the data I can find is either obscure or specific. As in I can find technical specs (which I don't know what to do with), or I can find fuel data for very specific missions but with no way to extrapolate to something useful for myself.
Thanks for any help :)
Actually in case it is necessary I'll give an example of something I'd like to calculate with this - 500,000kg payload, 1au travel. Actually I guess it might involve multiple drives... which might make things more complicated. So I'll leave this as-is for now and see what kind of response might turn up.
Edit: Correcting this due to being very tired and asking the question badly. As has been pointed out, I should be using deltaV not distance.
As such, what I'm looking for is the derived equation from the rocket equation, where I can enter the target deltaV and the specific impulse of the engine, and the equation will spit out the fuel mass required per kg of payload. This may actually be within my ability to solve... but I've never been confident in rearranging formulae.