Laser cannon
From Tardis Wiki, the free Doctor Who reference
A laser cannon was a weapon. The R1C was equipped with one, which was powered via the ship's ion drive.
When gravity began pulling smaller objects towards the R1C, blanketing it, the Fourth Doctor advised Jackson to use the cannon to blast their way through. The resultant heat melted the hull and damaged the cannon itself. Eventually, penetration was achieved and the ship broke free. (TV: Underworld)
