Sonic cone

Sonic cones were a device used for defending an area. When the perimeter was breached the object/being is atomised.

Gavrok deployed a sonic cone atop of the Doctor's TARDIS. Hawk breached the perimeter and his hand was burnt. Gavrok fell into the perimeter whilst in disarray and was atomised. With the power drained the Doctor merely removed it. (DW: Delta and the Bannermen)