Abstract: A method and apparatus for blasting of hard rock using a highly insensitive energetic material ignited with a moderately high energy electrical discharge causing the fracturing and break up of the hard rock is provided. The blasting apparatus comprises a reusable blasting probe including a high voltage electrode and a ground return electrode separated by an insulating tube. The two electrodes of the blasting probe are in electrical contact with a continuous volume of highly insensitive yet combustible material such as a metal powder and oxidizer mixture. The metal particles within the metal powder and oxidizer mixture form a plurality of fusible metal paths between the high voltage electrode and the ground return when subjected to an electric current delivered from a large capacitor bank coupled to the high voltage electrode.

Abstract: An electrothermal chemical cartridge with a fuse of tapering cross section enables higher impulse energy to be imparted to a projectile by means of complete controlled burning of propellant. A long, narrow tube filled with propellant has a fuse on its inside surface with a cross section that tapers toward the discharge end, separated from the electrical ground of the cartridge casing by a layer of insulation sufficiently thin to be destroyed as the fuse ignites the propellant. A high-voltage electrode connected at the back end of the tube provides for application of a pulse of sufficient current density to ohmically heat or burn the fuse in a controlled fashion from the discharge end to the back end. Many such tubes can be bundled together in a large casing for wide barrel guns.

Abstract: An electrothermal chemical cartridge with a fuse of tapering cross section enables higher impulse energy to be imparted to a projectile by means of complete controlled burning of propellant. A long, narrow tube filled with propellant has a fuse on its inside surface with a cross section that tapers toward the discharge end, separated from the electrical ground of the cartridge casing by a layer of insulation sufficiently thin to be destroyed as the fuse ignites the propellant. A high-voltage electrode connected at the back end of the tube provides for application of a pulse of sufficient current density to ohmically heat or burn the fuse in a controlled fashion from the discharge end to the back end. Many such tubes can be bundled together in a large casing for wide barrel guns.