A plasma torch is a Starfleet cutting tool which uses a plasma stream to cut through objects. (VOY episode: "Equinox"; ENT episode: "The Forgotten")

Hikaru Sulu accidentally pressed an activated plasma torch against the Enterprise warp core his first week aboard that vessel, nearly destroying the ship. Afterwards, he learned some "exotic Scottish expressions" from Chief Engineer Scott. (TOS short story: "Chaotic Response")