Modeling source-to-receptor atmospheric transport : Atrazine, PCBs and dioxin in North America

A downhole tool apparatus for use in a well includes a housing having a cylindrical chamber defined therein. A power piston is slidably disposed in the cylindrical chamber and divides the cylindrical chamber into first and second chamber portions on opposite sides of the power piston. First and second explosive charges are contained within the housing and communicated with the first and second chamber portions on opposite sides of the power piston. Firing of the first explosive charge moves the power piston in a first direction. Firing of the second explosive charge moves the power piston back in a second direction opposite the first direction. Thus, the operating power for a downhole tool is provided by selective firing of explosive charges which provide the operating pressure to move the power piston of the tool.