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?