A phased ionic pulse was a type of ion particle emission, that could be generated by starships. On Federation ships, such a pulse could be initiated from the lateral sensor arrays, science labs or from any bridge science station. The prototype metaphasic shield system invented by Dr. Reyga was vulnerable to phased ionic pulses.
In 2369, the Takaran scientist Jo'Bril attempted to fake the failure of the technology during the test flight. A phased ionic pulse beamed into the metaphasic projection matrix resulted in a temporary system malfunction, a disruption of the metaphasic shield, during which a tetryon field formed inside the ship. (TNG: "Suspicions")