Thank you TechFan and John Sand.
Thanks to your replies I'm calling this the Michael Lewis Krausen Catcher.
Just to be certain that I communicated, here's a picture worth 1000 words. All I had available was an old bleach jug into which I bored a hole so I could mount a standard 3-piece...
In the 1980's I took Prof Michael Lewis' two weekends home brewing class at Davis.
Michael taught us many tricks. I don't have the bandwidth to try and trick Google into finding if home brewers are still using them.
I want to know if the approach to brewing I describe below is well documented...