IMO; that sounds really cool. I think it is the future for propulsion.

Too bad it needs Xenon gas, that makes the engine unsustainable, Any other material like space rock would be better, though hard to collect in empty space, because of the speed difference.

7kw is about 7000 / 640 watts per horsepower = 10.9 horsepower that doesn't sound anything at all like the amount of power needed to support a coin on a table.
Now, what kind of nuclear power will they use to run it? How much does it mass? What is it's fuel mass loss? Couldn't they use a denser, solid material instead of xenon and heat it to the useful temperature and save on storage mass/volume? Can the process be scaled up to 1000 times current power? Can any form of mass be used as long as it is heated to gas/vapor temperature? If so, then you could use solar panels when near a sun for power and then use their mass as fuel when away from the sun. Thus reducing vehicle mass at the same time.

Encouraging research and development projects continuously produce results, such as the Xenon ion thruster for future space exploration missions. Evidence of remarkable achievements continue in most all the disciplines, except in the realm of humanity's domain and condition . Billions are spent in pursuit of knowledge relevant to areas of science which currently have little to do with the human condition overall. In effect, - hanging curtains before the house is built. Agreed, - it isn't all negative, since much has been discovered which has produced beneficial knowledge applicable to the development of new discoveries in biology and medical science. However, nothing of tangibility has so far been discovered to transform human nature which will allow it to overcome the destructive influences of 'greed' and the lust to control and dominate other members of our species to a status-dominated sub-cultural state.

"What this means in simple terms is that the NEXT engine can make a spacecraft go (eventually) very far and very fast."
How far? How fast?

I was under the impression that ions could be gathered in space much as rocket engines gather more combustible air to accelerate as the ion propulsion systems gather speed. Aren't ions available everywhere in space? And the only thing necessary is to gather and channel them for thrust? Or am I just such a neophyte that I believe in Star Trek too much?

@ notarichman
This engine is for space travel. Not take-offs or landings. And in space, where there's pretty much nothing to slow down the spacecraft, any amount of force will do. This engine is a constant, reliable and durable source of thrust, which is exactly what NASA wanted for space travel. This engine is gonna get people to Mars one day.

the only problem i have with this type of engine is it leaves no room for error in navigation. what about the plasma engine more power required but far more thrust.

Better yet this engine or one like it will get us to Mars in weeks instead of months.

@Nitrozzy: error in navigation? I don't think that's an issue. Traveling through space isn't like missing the exit ramp on the freeway, it's pretty straightforward.