Abstract: Method and apparatus for plasma blasting comprises a capacitor bank for storing electrical charge to which is coupled an inductance which delivers the electric charge as a current through a switch to an explodable conductor comprising a portion of a probe. The explodable conductor is a ribbon helically wound on a cylindrical mandril, the ribbon having a given length to cross section ratio which is proportional to the square root of the ratio of the inductance to the capacitance in order to ensure efficient dissipation of an optimal amount of the electrical energy stored in the capacitance.