concentrator

noun

1. One who concentrates.

2. (telecommunications) A hub.

3. (mining) An apparatus for the separation of dry comminuted ore, by exposing it to intermittent puffs of air.

4. (firearms) A frame or ring of wire or hard paper fitting into the cartridge case used in some shotguns, and holding the shot together when discharged, to secure close shooting; also, a device for slightly narrowing the bore at the muzzle for the same purpose.