The Psi Disruptor is a powerful piece of technology in the StarCraft universe.

It was created by Terran Confederacy scientists on Tarsonis but never used. Arcturus Mengsk looked for it after the defeat of the Zerg but never found it. It's psionic field can disrupt Zerg communications, rendering them much less effective in warfare. It requires huge amounts of power to run, and so is connected to several external fusion power generators in addition to it's internal generator.

However, the expeditionary force of the United Earth Directorate found it, but had the misfortune of adding Samir Duran to their side before this occurred.

Duran convinced Admiral DuGalle to destroy the Psi Disruptor, possibly using psionics to manipulate his mind, but Vice Admiral Stukov (possibly a Terran Ghost and possibly capable of resisting Duran) sabotaged him. His personal troops said they would destroy the Psi Disruptor but instead disassembled it.

Later on, Stukov reactivated the Psi Disruptor on Braxis, which caused Admiral DuGalle (who was probably not thinking straight at the time) to order Duran to kill him.

However, Stukov appealed to his personal friendship with DuGalle, and, as he lay dying, convinced DuGalle to use the Psi Disruptor against the Zerg. Duran then set it's self-destruct, and the Zerg promptly attacked the Disruptor, but DuGalle and Stukov's men defeated them and prevented it's self-destruction.

DuGalle left a planetary garrison behind to protect the Psi Disruptor on Braxis, and found to his joy that the Zerg on Char could not fight back effectively. Indeed, the UED forces could destroy Zerg Cerebrates which wouldn't reincarnate (the second Zerg Overmind displayed this ability before). The UED won a great victory on Char.

Because Stukov had been forced to hide the Psi Disruptor, it was now located on Braxis with minimal forces to guard it. Kerrigan tricked Jim Raynor and Arcturus Mengsk into helping her destroy it.

As Stukov was already dead, and the UED force was wiped out on Char, it is unlikely anybody knows how to create a new one.

References

• StarCraft homepage at Blizzard Entertainment
• Battle.net StarCraft Compendium