English Electric Valve Company Limited

Timothy P Donaldson

Hugh Menown

Arthur Maitland

Christopher V Neale

Raymond P Knight

Colin A Pirrie

John R Shepheard

A magnetic thyratron interrupter is provided having between an anode and a cathode a structure having an aperture therein for a discharge presenting a succession of surfaces in the direction of discharge which are contacted when the discharge is moved by applying a magnetic field transversely to the discharge direction. Examples of structure are stacks of discs having concentric holes which are alternately of larger and smaller diameter and a strip of gauze wound into a spiral.

Thyratron interrupters

A thyratron utilizable as a circuit interrupting protective device is provided. The thyratron includes an apertured grid between anode and cathode which is divided transversely into two parts separated by an insulating layer. Both surfaces of the composite grid remote from the insulating layer carry conductive meshes which meshes cover the exits of the apertures in the composite grid. The thickness of the insulating layer and the dimensions of the meshes are such that no point within an aperture is further from a part of the grid or a mesh than the Debye distance whereby the effects of Debye shielding tend to be reduced when a negative potential is applied between two said parts of said grid to quench a discharge previously initiated by applying positive potential to both parts of the grid.

Electric circuit interrupting devices

Conventional discharge tubes comprise electrodes within a separate containing vessel. The electrodes are joined to an external circuit by electrical conductors which pass through the vessel wall via an insulated side arm. Such a construction has disadvantages in that careful manufacture is required and it is also difficult to produce a desired distribution of the active medium in a laser and maintain a stable optimum temperature. In an attempt to reduce these problems the invention provides a discharge vessel which comprises electrical conductors and insulators arranged alternately so that a separate discharge vessel is not required. Since the discharge vessel is partially thermally conducting, temperature control is facilitated by its fast response to stabilizing controls, heat being supplied from an external source. When metal is used as all or part of the active medium, the electrodes may be lined on their inner surfaces with the metal and each of the electrodes can be controlled independently from the others to obtain a desired distribution of metal vapor.

Metal vapor segmented discharge tubes

The invention provides a glass enveloped thyratron having an anode carried by an anode pin extending through a glass neck in the thyratron envelope and forming a pant leg. The anode is surrounded by a screening box operated at cathode potential which has a back plate with a tubular portion extending away from the anode into the interior of said pant leg to surround said anode pin. The outer surface of the extremity of the pant leg is flared outwardly adjacent the back plate into engagement with a mounting collar secured to the rear of the back plate. The tubular portion of the back plate extends within the pant leg for a distance substantially greater than the extent to which the pant leg is enclosed by the mounting collar.

Thyratrons

It is desirable not only to switch between circuits or circuit elements carrying relatively large currents but also to effect the switch-over operation extremely rapidly. Conventional thyratrons can be used to switch on the current, but they cannot easily be switched off so quickly. The invention seeks to solve this 'switch-off' difficulty by using the principle of plasma particle diversion together with a new thyratron design which can be used as a 'switch-over' device. As can be seen from FIG. 1, the invention provides a thyratron having:

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Great Totham, United Kingdom

Timothy P Donaldson