Neumann Space Ion Engine Sets Record for Specific Impulse
neumannspace.com
neumannspace.com
Your power source mass dwarfs the reaction mass ("fuel") really quickly.
Basically, for equivalent thrust, with twice the specific impulse you require half the fuel but double the power.
So often with electric propulsion you get a better, lower spacecraft mass by using lower specific impulse! This means more reaction mass but smaller solar panels / power electronics.
That's why things like hall thrusters are used, with ISP around 1000s compared to 3000 s gridded ion engines.
Maybe for a Venus or Mercury mission where you have plenty of power and need large delta vees...
>> In our system the cathode is a cylindrical rod of conducting material that we choose to use as fuel (eg magnesium, vanadium etc).
This is wrong. They are using it as propellant, not fuel.
Probably limits total mass though so maybe use it for very low acceleration missions where you can use the high isp. Like stationkeeping indeed.
My experience playing Kerbal Space Program, if accurate, suggests that such an engine is more effective for longer term missions, because the increased SI comes at a cost of lower max thrust (I.e. it takes longer to accelerate); I suspect this is not very accurate IRL as all our missions take a very long time so this problem may be irrelevant. Also looking below it seems such an engine is limited by electric power (solar panel/battery).
Hence this leads me to believe this type of engine allows us to extend the range of our missions but at the cost of longer mission durations.
KSP's ion engines are WAY overpowered to make for better gameplay.IRL thurst is lower by orders of magnitude.
If we are talking about probes in the solar system, then the mission durations are already long to begin with. Instead of firing a conventional hydrazine-based thruster for a few minutes, we'll fire an ion engine for months. But, if it takes years to get where you are going, who cares?
There are things we can't do yet, such as orbital insertions, with ion engines. In these cases, conventional engines are better.
We can do orbital insertions - if we approach a planet or asteroid with parabolic speed, we need only small change to get to an elliptic orbit, and that orbit can be later shaped as we need.
What we can't do is a launch or landing with bodies with sufficient gravity - like Moon or Vesta. There we don't have time to accelerate.
(This also disqualifies solar sails, which is a shame, because I'd love to play with them.)
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