Starfleet has been playing with the idea of Phaser Cannons for well over 50 years. Numerous test prototypes have been produced and unfortunately failed.
A Phaser Cannon, takes a large amount of phased energy and bundles it in a cohesive shell. This shell is either magnetic or graviton based, however over distance it does dissipate, leaving the phased energy to escape into space, rendering it harmless. The Klingon, Romulan and Breen Empires all have developed Disruptor technology and developed it to a point where it is a very effective weapon with an excellent range.
The Federation however took a different path in the design of its phased energy technology, opting for a more refined singular beam. This Type X array has severed Starfleet well, however it does have its downfalls. Helm to Tactical response times were highly unacceptable with a mobile, very powerful attack force. This factor, in combination with phaser array refocusing time forced Starfleet to develop the new Phaser Cannon. This development project was also pushed into being by the first Borg Encounter in system J-25. Previously all test projects had failed, however this time, with help from Malz, a renown Klingon scientist the highly unusual Federation style Phaser cannon came into being. The cannon uses a pulse modulated graviton shell to hold the phased energy together, the energy itself being fed directly from the Warp engines (instead of from batteries supplied by the warpcore). Once fitted to the Defiant these cannon (four all together) proved to be excellent in simulated wargame exercises, the Helm to Tactical response time nearly flat lined. However problems arose with the amount of energy being channeled from the Defiants oversized warpcore. There was massive recoil problems with the ships warp nacelles threatening to be torn off, the SIF not able to cope with the extra stress.
The problems were, over time, cured by Designers, but not before Starfleet had officially closed the project after Primary testing. When the ship came out of storage engineers already had a blueprint of how to modify the SIF so the Cannons were no longer a problem.
