Psi disrupter

"We've just received word from our research team that they've uncovered some kind of hidden weapons relay upon the planet Tarsonis. They report that it's called a Psi Disrupter, and that its purpose is somehow connected with the Zerg."

- UED Vice Admiral Alexei Stukov

Psi disrupters are terran devices used to hamper zerg communications and movement.

The Great War
The first psi disrupter was developed by the Terran Confederacy to interfere with the zerg psionic link, fragmenting the Swarm's gestalt and rendering it less effective on the battlefield. It was constructed on Tarsonis but it was not activated during the zerg invasion. The nascent Terran Dominion attempted to locate the Disrupter but could not find it; it was thought lost.

The Brood War
The disrupter nonetheless survived the invasion of Tarsonis and was finally recovered by the United Earth Directorate Expeditionary Force in the Brood War, only to be slated for destruction by order of Admiral Gerard DuGalle. A local Confederate rebel leader, Samir Duran had convinced the admiral, above the objections of Vice-Admiral Alexei Stukov, that the disrupter would undermine the UED's plan to enslave the Overmind. To prevent this Stukov dispatched his own troops to take over the "demolition" of the disrupter, who secretly dismantled and shipped it to Braxis for reassembly.

Stukov's duplicity was soon discovered and a UED strike force led by Duran landed on Braxis with orders from DuGalle to not only destroy the disrupter but execute the Vice Admiral as well. The strike force succeeded in mortally wounding Stukov but before dying he revealed Duran's treacherous nature and successfully appealed to the admiral to spare and use the Disrupter. Duran then attempted to destroy the device by activating the self-destruct, but UED troops were able to foil this attempt in time despite the sudden appearance of zerg forces. A UED garrison was deployed to safeguard the now-active disrupter.

The disrupter proved its worth in the ensuing UED assault and victory on Char. The second Overmind was captured and the UED began taking control of the Swarm in the sector, creating Slave Broods. The effects of the Disrupter were widespread and severely weakened Kerrigan's control over her own broods.

Kerrigan rallied the sector's factions suspicious or hostile to the UED to her and, as a first step to ousting the invaders, led them on a strike against the disrupter on Braxis. A small team led by Jim Raynor first destroyed a number of large external power generators feeding the Disrupter. With the disrupter offline, Kerrigan used a psi-emitter provided by Arcturus Mengsk to reassert control over local zerg creatures, including a number of special zerg warriors, creating an army which was used to finally destroy the Disrupter.

The Second Great War
Despite the destruction of the disrupter and the UED force, the legacy of both endured. UED studies had discovered that concentrated doses of sigma radiation could slow zerg movement and reaction speeds by as much as 50%&mdash;discoveries backed up by Doctor Egon Stetmann during the Second Great War by observing the detrimental effects sigma radiation had on zerg tissue. It would take a lot of work and effort to safely deploy sigma radiation on the battlefield to the extent where zerg would be slowed, but he concluded that it might be worth it.

StarCraft
The Brood War game building doesn't have any special abilities.

In Patriot's Blood, its interior was used as an installation map. Its internal defenses include a number of gun traps.

In Reign of Fire, it was shut down by an attack by Raynor's Raiders, and then destroyed by Infested Kerrigan's forces.

StarCraft II
In StarCraft II: Wings of Liberty, a psi disrupter can be built, unlocked via 25 zerg research points. It decreases the movement and attack speed of all non-heroic zerg units in a small area.

In the final missions of the Wings of Liberty campaign, psi disrupters enhance defenses when co-located at choke points and above ramps; this makes it more difficult for zerg to approach and overrun defenses unscathed. Psi disrupters are less effective against zerg flyers, especially brood lords.

In StarCraft II: Heart of the Swarm, psi disrupters took part in the ineffectual defense of Korhal Palace during Kerrigan's invasion of the planet.

Development
The psi disrupter was among the last terran buildings designed for Wings of Liberty, alongside the hive mind emulator and automated refinery. Most of these buildings were one-shots with no revisions but had the benefit of getting higher texture polish.

The psi disrupter may have initially been called the "sigma projector."