Psionic field
A psionic field was a bioelectric energy field with a psychoactive effect utilizing psionic energy. 

The Botha of the Delta Quadrant used a psionic field modulating on a delta wave frequency to trap the crews of starships in vivid hallucinations. They employed this attack against the  in 2372, apparently generating the field from three ships. B'Elanna Torres believed that a resonance burst from the warp core would be able to block the field. With help from The Doctor, Kes was able to resist the Bothan's telepathy long enough to trigger the burst. After the Bothan was defeated, he and his ships were revealed to be illusions themselves, and thus the truth behind the psionic field remained a mystery. ()

See also
Psionic energy
Psionic residue
Psionic resonator
Psionic signature
Energy
physics