The research that was done on Khalek, Anubis's genetic experiment, revealed that specific portions of Khalek's brain were active when he was using his special abilities. Working on the assumption that the Ori were affecting the Priors in much the same way, Carter and Dr. Lee, with assistance from Orlin, developed a prototype device designed to target and neutralize the higher brain functions of more highly evolved individuals by using a field generator that emits omni-directional fluctuating ultrasonic frequencies. The auditory senses provide a direct line to certain brain functions which respond differently to different sonic frequencies, and the success of the device depended upon identifying and isolating the exact frequency that would target a specific area of the brain. The resulting technology, referred to as an anti-prior device, was designed to prevent a Prior from accessing the highly evolved area of his brain that gives him superhuman abilities and special powers such as telekinesis, and because the Prior's staff is also mentally activated, it would neutralize his ability to use the staff as well. The symptoms were colorfully described as an inability to concentrate, "dizziness, irritability, mild nausea, and a condition known as hot dog fingers."
A saucer-shaped device approximately one foot in diameter with flashing blue lights that indicate its level of operation, the prototype was first tested on the Sodan world of P9G-844 in an attempt to subdue a Prior and obtain a blood sample that might hold the key to curing the Prior plague on Earth. The device's emitter was programmed with a range of frequencies, and a remote control was used to adjust random frequencies until the correct one was found. As the Prior held Mitchell suspended in mid air, Daniel adjusted the frequency settings through trial and error until the correct one was found. With his special abilities blocked, the Prior released Mitchell and collapsed from a single shot from a zat. Although the prototype was successful, and the specific frequency was identified for future use, SG-1 discovered that the effectiveness of the anti-prior device is only temporary since Priors are capable of adapting to the technology and overcoming its effects.
When Daniel became a Prior and was captured by SG-1, he was restrained and the anti-prior device was activated to prevent him from using his special powers. Again the device worked for only a limited time as Daniel learned to overcome its effects and escape. However, he used the device against Adria, and it was equally effective against the Orici. SG-1 used the device once again when they attempted to capture Adria, and when Ba'al snatched Adria away from SG-1, he used similar technology by flooding the area in which she was held prisoner with the same kind of EM field that is generated by the anti-prior device.
Cross Reference: Adria, Brain Scan Device, Khalek, Bill Lee, Orlin, Prior, Prior Plague, Prior Staff
Episode Reference: The Fourth Horseman, The Shroud, Dominion