I'm not sure if the maths are related, but there is a different (though similar)...

winwang 66 days ago | parent | context | favorite | on: Amplification of electromagnetic fields by a rotat...

I'm not sure if the maths are related, but there is a different (though similar) idea in gravitational slingshots. It's not the same because it simply uses "normal" linear momentum. But I also only read the abstract, lol.