Suppose a satellite in LEO wich have a ion thruster, this ion thruster have a grid accelerator and in LEO there are a high density of plasma by the ionosphere, thus the particles of the ionosphere can enter the chamber of the thruster? if this occurs i think it can be a problem

For example, if the outer grid is biased negatively then will attract ions of the ionosphere and then produce a thrust in the opposite direction of the thrust generated by the thruster enter image description here

And after the external ions enter the thruster, are they accelerated outward again?

  • $\begingroup$ An energetic-enough positive ion could run uphill against the accelerating potential, and with enough energy could overcome the total potential. I think you are overestimating both the number density and average energy of ions in LEO. $\endgroup$
    – Jon Custer
    Jul 9, 2021 at 18:09
  • $\begingroup$ @JonCuster between roughly 200 to 400 km the residual atmosphere is primarily atomic oxygen. Not being chemistry literate I can only speculate that there may be some O⁻ up there. Potentially related factoid, an oxygen atom would need to pick up 5 eV of kinetic energy to match orbital velocity in LEO. $\endgroup$
    – uhoh
    Jul 9, 2021 at 23:42
  • 1
    $\begingroup$ Ion thrusters will operate well above 5V. $\endgroup$
    – Jon Custer
    Jul 9, 2021 at 23:47

1 Answer 1


There are some papers about the interaction of ion thrusters with the ionosphere, see:


Simulations were done between 160 and 250 km. But the region 450 km and above was not studied. enter image description here

This image from the first paper shows a wake front shielding the ion thruster from the molecules of the ionosphere. So these molecules could not enter the chamber of the thruster.




All these papers are about VLEO , the range from 160 to 250 km.

LEO is defined as the range from 450 to 2000 km. At these heights interaction of ion thrusters with the ionosphere seems to be no problem at all. The remaining ionosphere is so thin there that interactions may be neglected.

  • 2
    $\begingroup$ I see you've added some more now, thanks! $\endgroup$
    – uhoh
    Jul 9, 2021 at 23:45

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