I see those donuts on a rope contrails daily.
If I would take a pic of the sky at any moment you'll see an odd trail.
Holland is one of the busiest skies in europe.
I actually saw contrails that looked excactly like the famous donut on a rope pic, many times this year.
If the aurora had pulse detonation engines you would not be able to see the rings. In a pulse detonation engine the engines have to fire several
times a second so the smoke trail would be constant. The donut on a rope contrails look like a pulse detonation engine that is firing about once a
second. Way to slow.