The Bad Astronomer on air-breathing space engines:

That pink glow is from ionized nitrogen and oxygen molecules.
So in general this is like the ion drive on the spacecraft
Dawn except, of course, not using a stored gas but the gathered (though extremely low pressure) ultra-high altitude atmosphere of the Earth as the propellant.
And--get this--such a system might not only be used to reboost satellites back into a higher orbit WITHOUT having to carry any fuel to do this, but this could be used to MAINTAIN a satellite in a relatively low orbit of less than 200 km up. There is an altitude range of between about 120 and 200 km up which is not usable by any long-term satellites because the atmospheric density is too high.