Patent ID: 7909116

Claim:
A system for excavating a subterranean formation including a drill string having a a bit end, the system comprising: a drill bit connected to the bit end; a plenum formed in the drill bit that defines a plenum volume, wherein the plenum is in communication with and receives a suspension of a liquid and a plurality of impactors from the drill string; a cavity extending from the plenum that defines a cavity volume that is less than the plenum volume so that the impactors are accelerated when flowing from the plenum to the cavity, wherein the cavity is in communication with and receives the suspension of liquid and impactors from the plenum; a nozzle disposed in the cavity in communication with and receiving the suspension of liquid and impactors from the cavity and discharging the suspension of liquid and impactors to remove a portion of the formation; and a junk slot formed in the drill bit to define a passage between the drill bit and a wall of a well bore in the formation, wherein the junk slot is disposed at a location on the drill bit relative to an orientation of the nozzle such that a flow of impactors discharged from the nozzle impact the formation at an angle and rebound into the passage rather than impacting the drill bit.