Interesting. I'd like to see how they propose to ionise that quantity of air, and what the energy cost is. If the energy consumed to ionise the air is greater than the gain then I don't see it working. (do I get a prize for stating the bleeding obvious?)
The article mentions electron beams. What sort of eV energy would be required to ionise that kind of massive airflow?
And what about the weight penalties for the electron guns?
Would be very interesting to see more detail.
Of course, the big question is why? We don't currently have, nor are there planned, any supersonic, let alone hypersonic passenger aircraft. If it was for some kind of missile system or fighter then I could understand it, but it seems to fill a niche that simply doesn't exist in the civil industry. Of course it's possible that it might lead to improvements in fuel economy for normal jet engines.
The jury's out on this one for me.