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Can a propulsion system be made by facing two air ionizers towards each other, accelerating the ions with fans, and having them repel each other? Would the force generated be greater than just accelerating normal air (not ionized)?

Something like this: enter image description here

Thanks in advance

Antonio1234
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  • I erased my answer, I am not so sure I interpreted well your question. –  Jun 25 '16 at 00:25

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There's one question that needs to be addressed with any form of ion propulsion: what do you do with the opposite charged particles? In the diagram you've drawn, it's the positively-charged ozone ions that are being used for the propulsion. The electrons have to have somewhere to go too, otherwise your ionized gas will be electrically neutral and not repel itself.

If you can figure out somewhere for the electrons to go, I'd say this would probably work. As long as mass with momentum is flying away from a vessel in an anisotropic way, you'll have propulsion.

The real question is whether this form of propulsion can be engineered in such a way that it is competitive with existing forms of propulsion.

It is also worth asking where on earth such a form of propulsion can be safely used without the very hot exhaust burning stuff up. I don't think it could be used anywhere on the ground without serious consequences, so it's only suitable for air travel.

It is worth noting that propulsion systems using ions for thrust have been used on spacecraft, most notably the asteroid-exploring Dawn spacecraft. These engines normally have some sort of metal as their source of ions and the ions are directed using magnets. Ion engines are notable for their very high specific impulses, or how much change in momentum a given mass of propellant can produce.

NeutronStar
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  • Assuming I can figure out somewhere for the electrons to go, would there be any way to calculate the force produced by this propulsion system with an equation? – Antonio1234 Jun 26 '16 at 13:06
  • $F=ma$. Figure out how much mass you're throwing out, how much that mass has been accelerated, and you can calculate the force used to accelerate the ions, and then relate that back to the force on the spacecraft using Newton's Third Law. – NeutronStar Jun 26 '16 at 20:49
  • Theoretically wouldn't the actual system produce less force by accelerating the ions at each other than just using the two fans for propulsion? – Antonio1234 Jun 28 '16 at 15:42
  • @Antonio1234, possibly. It all depends on how much the ions get accelerated going out the exhaust. – NeutronStar Jun 28 '16 at 16:14
  • To do this I would use Coulomb's law, is it possible to determine the distance between the charges based on the force directing them towards each other? – Antonio1234 Jun 28 '16 at 16:45
  • @Antonio1234, it would be much easier to put things in the framework of "collisions" and look at the change in momentum of the ions, and equate that with the change of momentum of the spacecraft.

    https://en.wikipedia.org/wiki/Coulomb_collision

     – NeutronStar Jun 28 '16 at 16:52
  • Thanks for the help, I got that change in momentum is about .00001554 kg m/s assuming b=10^16 and v=.183 and Ze = 1 (I used o2- instead of o3) if i were to increase velocity, i would see an increase in momentum, correct? (my calculations may be a little off) – Antonio1234 Jun 29 '16 at 04:36