Warp Flare
From Star Trek : Freedom's Wiki
A warp flare is the designated name for a Photon Torpedo that has been reconfigured to emit a sustained polyluminous burst.
While traveling across a region of the Delta Quadrant known as the Void, the Federation starship USS Voyager encountered an alien species that used dampening fields to drain energy from encroaching ships. The dampening field caused a massive blackout aboard Voyager plunging the crew into further darkness. In response, Tuvok reconfigured a torpedo to act as a warp flare in order to shed some light on their situation. (VOY: "Night")