Static diffuser
The static diffusers on the Cerritos begin to purge with Boimler still inside
A static diffuser was a component of the grav stabilizer on California-class starships, located close to the bridge. When the ship's engines were engaged, the diffusers were purged of static, causing them to briefly fill with fire.
In 2381, Ensign Brad Boimler attempted to reach the bridge of the USS Cerritos via the catwalk over the static diffusers. The diffusers began to purge while he was still inside, and he only narrowly managed to escape through a side hatch. (LD: "We'll Always Have Tom Paris")