Graviton emitter

A graviton emitter was a device capable of producing and directing an energy form with gravitational properties.

In 2369, the crew of the USS Enterprise (NCC-1701-D) used their graviton emitters to to neutralize tetryon emissions being transmitted through a spatial rupture from a tertiary subspace manifold. Although a group of aliens on the other side of the rupture were temporarily successful in counteracting the pulses, Lieutenant Commander Geordi La Forge managed to program the emitters for a full-spectrum pulse compression, and was able to close the rupture. 

In 2373, the crew of the USS Defiant (2370) utilized a phase-conjugate graviton emitter in their tractor beam when retrieving a crashed Jem'Hadar fighter from Torga IV. 

Later that year, the crew of Deep Space 9 utilized the station's graviton emitters to fire a phase-conjugate graviton beam at the Bajoran wormhole in an attempt to seal the wormhole and prevent a Dominion invasion of the Alpha Quadrant. The beam was meant to collapse the wormhole's spatial matrix and close it forever, but due to sabotage to the emitters by a Changeling disguised as Doctor Julian Bashir, the beam had the exact opposite effect, making the matrix even more stable. 

The same year, Arissa, a visitor to Deep Space 9, pointed out to Quark that an individual on the upper level of his bar was utilizing a small graviton emitter hidden in his ring to manipulate Quark's dabo table, helping an associate to cheat at the game.