Solid state high energy electrical switch for under-sea-water electric discharge seismic generator

Claim 1

A seismic generator apparatus including a source of direct current, a capacitor means connected to said source to be charged thereby, and a capacitor discharge circuit connected to said capacitor means including in series in any order: an electrical switch, and an electrode system for under-sea-water conduction, said apparatus being capable of producing a high intensity acoustic pulse at said electrode system when said capacitor means is discharged through said electrode system, said pulse being sufficient for subbottom seismic surveying, said apparatus being further characterized by: said switch including an inductor means in series with a mesh, said mesh including a plurality of cross connected parallel branches for capacitor means discharge and for voltage control, the capacitor means discharge group of branches comprising: a string of a plurality of SCRs connected isotactically in series, a string of a plurality of series connected resistance and capacitor circuits, i.e. RC circuits, connected isotactically in series with each other and each paralleling one of the SCRs, except for one of the SCRs, forming an SCR gate control sub-branch circuit, an intermediate point of each resistance of said RC circuits being connected to the gate of the SCR in parallel with the RC circuit, and said one SCR being the one in said string of SCRs whose cathode is nearest the negative side of said source of direct current.