The weapon is capable of severing the communication between the blocks of Replicators. They are the only weapons, besides conventional Tau'ri guns, capable of actually destroying a Replicator. However, the weapon can also sever the connections between the blocks of Human-form Replicators, whereas conventional projectile weapons cannot. The Asgard had previously experimented with a device that would do much the same thing, without success. The weapon discharges a blue energy wave. Other variants were created, including disruptor cannons, capable of wiping out any Replicator on a planetary scale, and a satellite variant, which can wipe out Replicator ships in space. (SG1: "New Order, Part 2", "Gemini")
The weapon was created by Colonel Jack O'Neill during the second time he had the knowledge of the Ancients downloaded into his mind via the Repository of knowledge. Although he was in stasis at the time, Thor, Dr. Daniel Jackson and Teal'c were able to communicate with him by using the Asgard computer O'Neill was linked to. Thanks to the computer he was able to virtually create the weapon after which Thor synthesized it. However, after O'Neill's Ancient knowledge was flushed out of him he had no idea what the device was. When the Human-form Replicator on Thor's ship, Eighth, tried to kill them, and FN P90 Personal Defense Weapons were ineffective, O'Neill picked up the disruptor and fired it at the Replicator which destroyed it. Thor later used the disruptor to create a disruptor cannon mounted on his ship to destroy all Replicators on the surface of Orilla, their new homeworld. However, a small number of Replicators led by Fifth managed to escape before the weapon activated. (SG1: "New Order, Part 2")
After learning that Fifth was heading straight for the Milky Way to take control of the galaxy, the Asgard were able to create a satellite variant and sent it to the Alpha Site. They attempted to upgrade the weapon since Replicator Carter, the Human-Form Replicator doppelganger of Lt. Colonel Samantha Carter made them believe that Fifth created a cipher to block the weapon, a claim that later turned out to be false. The weapon worked and Replicator Carter used it to destroy Fifth and take control of the Replicators for her own purposes. She managed to create her own cipher to render the disruptor technology useless. (SG1: "Gemini")
Eventually Carter managed to overcome this cipher with Thor's help. However, after the first shot the Replicators adapted alarmingly quickly. In the end they were able to simultaneously hit all the Replicators at once with the help of Jacob Carter and Ba'al, by reconfiguring the Ancient superweapon on Dakara to destroy them. (SG1: "Reckoning, Part 1", "Reckoning, Part 2")
Sometime after the fall of the Replicators, and the encounter with the Asurans in Pegasus, Carter created a new gun version which was named Anti-Replicator gun. Eventually the Asurans managed to override this new version. (SGA: "Progeny", "The Return, Part 1", "The Return, Part 2")
Behind the scenes
Knowing Richard Dean Anderson would play around with the disruptor, the model shop team who made the prop made it more robust, so it could not be easily damaged.