Stabilizing/ mass loading tubes with top contact?

Has anyone ever experimented with the idea of placing some sort of open grid above tubes that would stabilize them (by utilizing a contact point), mass load and damp them? My (perhaps ill conceived) concept being that the tube now has 2 points of stabilization - the base and now the top. I believe there are some electronics applications (military planes) where the tube is stabilized from the top with a spring and held in place.

Would this damp vibration and lower the resonance point better than just a tube damper? Obviously I'm thinking of an open framework that would still allow heat to rise.

Any thoughts on this?
emailists has helped my tubed equipment.
You could ask Steve Herbelin about your idea, since he makes his living by controlling tube microphonics, and his tube damper product line has continually evolved.
I use Marigo Audio 3mm white dots at the base of all my tubes, including rectifier tubes. The results are truly stunning. Happy listening.