Safe electrical initiation plug for electric detonators

Abstract

A device for initiating an electric detonator utilizing an open circuit to decrease occurrences of accidental detonation. The device may include an initiator housing, at least two conductor pins disposed through the initiator housing and spaced within the housing such that they are electrically isolated from one another, and a primer spot material disposed between the conductor pins. The primer spot material may be comprised of a mixture of reactive material and metal component. The primer spot material has electrical properties which provide resistance to conducting an electrical current to maintain an open circuit condition prior to occurrence of a breakdown voltage which is dependent upon the amount of metal component in the primer spot material. Subsequently, the primer spot material has electrical properties which provide a conductive medium on the occurrence of an electrical arc between the conductive pins that arises at voltages in excess of the breakdown voltage. Finally, the electrical properties are such that the electrical arc provides energy to form a plasma from the primer spot material, leading to initiation of the detonator.

What is claimed is:  
     
         1 . An explosive initiation device, for initiating an electric detonator utilizing an open circuit to decrease occurrences of accidental detonation, comprising: 
 a) an initiator housing;    b) at least two conductor pins disposed through the initiator housing, spaced within the housing such that the conductor pins are electrically isolated from one another; and    c) primer spot material disposed between the conductor pins, said primer spot material comprising a mixture of reactive material and metal component, such that the primer spot material has electrical properties which provide resistance to conducting electrical current to maintain an open circuit condition up to a breakdown voltage dependent upon an amount of metal component in the primer spot material, and which provides a subsequent conductive medium on occurrence of an arc between the conductive pins that arises at voltages in excess of the breakdown voltage, whereby said arc provides energy to form a plasma from the primer spot material.    
     
     
         2 . An initiation device in accordance with  claim 1 , wherein the primer spot material comprises a mixture of HMX explosive and from about 8% to about 12% aluminum particles by weight.  
     
     
         3 . An initiation device in accordance with  claim 2 , wherein the primer spot material further comprises about 5% to about 15% graphite particles by weight.  
     
     
         4 . An initiation device in accordance with  claim 1 , wherein the primer spot material comprises a mixture of HMX explosive and about 10% aluminum particles by weight.  
     
     
         5 . An initiation device in accordance with  claim 1 , wherein the primer spot material is a mixture of HMX explosive and about 9% aluminum particles by weight and about 9% graphite particles by weight.  
     
     
         6 . An initiation device in accordance with  claim 1 , further comprising a detonator shell containing a base charge, wherein the initiator housing is received within and coupled to the detonator shell, where the primer spot material is located in a direction extending toward the base charge.  
     
     
         7 . An initiation device in accordance with  claim 1 , further comprising a ferrule with an initiator housing end and a detonator end, wherein the initiator housing end is configured to couple with the initiator housing, and the detonator end is configured to couple with a detonator.  
     
     
         8 . A method of manufacturing an electric initiation element for a detonator with a variable range of initiation voltages, comprising the following steps: 
 a) providing an initiator housing;    b) disposing at least two conductor pins through the initiator housing, said conductor pins being spaced within the initiator housing such that they are electrically isolated from one another;    c) providing a reactive material useful as part of a primer spot material;    d) determining an amount of conductive component to achieve a range of conduction initiation voltages;    e) mixing the reactive material and the conductive component to form a primer spot material; and    f) disposing the primer spot material between the conductor pins, said primer spot material having electrical properties which provide resistance to conducting electrical current to maintain an open circuit condition prior to occurrence of a breakdown voltage dependent upon the amount of conductive component in the primer spot material, and which provides a subsequent conductive medium on occurrence of an arc between the conductive pins that arises at voltages in excess of the breakdown voltage, whereby said arc provides energy to form a plasma from the primer spot material.    
     
     
         9 . A method of manufacturing an electric initiation element for a detonator as in  claim 8 , further comprising the step of coupling a ferrule to the initiator housing, such that the primer spot material is located within the ferrule.  
     
     
         10 . A method of manufacturing an electric initiation element for a detonator as in  claim 9 , wherein the step of disposing primer spot material between the conductor pins comprises the following steps: 
 a) creating a slurry of primer spot material and lacquer; and    b) applying the slurry to the conductor pins within the ferrule.    
     
     
         11 . A method of manufacturing an electric initiation element for a detonator as in  claim 9 , further comprising the step of coupling the ferrule to a detonator.  
     
     
         12 . A method of manufacturing an electric initiation element for a detonator, comprising the following steps: 
 a) providing an initiator housing;    b) disposing at least two conductor pins through the initiator housing, said conductor pins being spaced within the initiator housing such that they are electrically isolated from one another; and    c) disposing primer spot material between the conductor pins, said primer spot material having electrical properties which provide resistance to conducting electrical current to maintain an open circuit condition, and which provides a subsequent conductive medium on occurrence of an arc between the conductive pins, whereby said arc provides energy to form a plasma from the primer spot material.    
     
     
         13 . A method of manufacturing an electric initiation element for a detonator as in  claim 12 , further comprising the step of coupling a ferrule to the initiator housing, such that the primer spot material is located within the ferrule.  
     
     
         14 . A method of manufacturing an electric initiation element for a detonator as in  claim 13 , wherein the step of disposing primer spot material between the conductor pins comprises the following steps: 
 a) creating a slurry of primer spot material and lacquer; and    b) applying the slurry to the conductor pins within the ferrule.    
     
     
         15 . A method of manufacturing an electric initiation element for a detonator as in  claim 13 , further comprising the step of coupling the ferrule to a detonator.  
     
     
         16 . A method of initiating an electric detonator, comprising the following steps: 
 a) providing an open circuit across a primer spot material comprising a mixture of a reactive material and a metal component;    b) applying a sufficiently high voltage to the open circuit to cause the primer spot material to ionize, thus creating a conductive medium;    c) maintaining the voltage across the conductive medium to cause the metal component to vaporize and form a plasma gas, thus creating heat and a shockwave; and    d) maintaining the voltage across the conductor medium to allow current to flow by means of the plasma gas thus creating a plasma gas arc, the plasma gas arc causing the reactive material to react, thus boosting the heat and the shockwave in a direction towards a detonator charge to initiate the detonator charge.