Electric circuit interrupting devices

In a thyratron including at least one apertured control grid disposed between an anode and a cathode;

• the improvement wherein:
• said at least one control grid is divided transversely into two electrically insulated electrically conductive parts which have a spacing from each other in the region of each aperture through said two parts which is less than the Debye length of each said region;
• each of said two parts includes a respective electrically conductive apertured layer having an electrically conductive grating on one surface covering each said aperture to define its exit;
• said electrically conductive apertured layers are disposed on the opposite surfaces of an apertured insulating layer with said gratings being on the opposite sides of said grid;
• and the portions of said two parts, including said gratings, defining each said aperture are configured and dimensioned so that no point within each said aperture is further from one or the other of said two parts than said aforementioned Debye length.