The basic theory of operation of the triggered spark gap is established, and qualitative and quantitative engineering design data are given. From the basic twoelectrode gap, a three-electrode or triggered gap model is established with its static and dynamic triggering characteristics shown. Several geometry conditions such as gap spacings trigger electrode hole sizes and insulator effects are discussed, showing their influence upon the triggering mechanism. A suggested trigger mechanism is given based on that proposed by Sletten and Lewis for the trigatron and modified to fit the present analysis. (auth)