Direct current energized pulse generator utilizing autogenous cyclical pulsed abnormal glow discharges
First Claim
1. A pulse generator comprising a cold cathode vacuum discharge tube having an anode and a cathode enclosed within an evacuated housing, wherein the cathode has an extended surface facing the anode and the cathode is capable of auto-electronic emissions under abnormal glow discharge conditions, which emissions have an extinction potential substantially higher than the sustaining potential of a vacuum arc discharge in the same tube, said discharge tube being connected in an external circuit comprising a continuous direct current source connected between the anode and the cathode, the external circuit being capable of delivering a potential sufficient to initiate auto-electronic emissions, and sufficient current at sufficient potential to drive said tube into a negative resistance region of abnormal glow discharge, the external circuit having an impedance sufficient that, as the tube is driven into said negative resistance region, potential between the anode and the cathode collapses below said extinction potential before a vacuum arc is established, whereby an endogenous cyclical pulsed abnormal glow discharge (PAGD) will occur, the cathode being of sufficiently robust construction to enable it to withstand sustained PAGD and erosion resulting therefrom without disruption or substantial thermionic emission, the surface of the cathode facing the anode being of a metal and having an area which promotes auto-electronic emission at much lower currents than predicted by the Fowler-Nordheim field emission theory, and the minimum separation of the cathode from the anode being at least about 2 cm.
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Abstract
A cold cathode vacuum discharge tube is used in a circuit for generating pulsed autoelectronic emissions which are particularly intense and frequent in the abnormal glow discharge region, and involve much lower current densities than predicted by the Fowler-Nordheim vacuum arc discharge region law. The discharge tube is characterized by a large electrode area at least of the cathode, and a large interelectrode gap. The electrodes are preferably spaced at least 2 cm apart in a parallel relationship. A probe may be introduced between the electrodes to reduce still further the field required to generate the emissions. In another configuration the probe forms the anode and two plates form cathodes. The circuit is driven from a direct current source of having an impedance sufficient to prevent establishment of a vacuum arc discharge.
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Citations
18 Claims
- 1. A pulse generator comprising a cold cathode vacuum discharge tube having an anode and a cathode enclosed within an evacuated housing, wherein the cathode has an extended surface facing the anode and the cathode is capable of auto-electronic emissions under abnormal glow discharge conditions, which emissions have an extinction potential substantially higher than the sustaining potential of a vacuum arc discharge in the same tube, said discharge tube being connected in an external circuit comprising a continuous direct current source connected between the anode and the cathode, the external circuit being capable of delivering a potential sufficient to initiate auto-electronic emissions, and sufficient current at sufficient potential to drive said tube into a negative resistance region of abnormal glow discharge, the external circuit having an impedance sufficient that, as the tube is driven into said negative resistance region, potential between the anode and the cathode collapses below said extinction potential before a vacuum arc is established, whereby an endogenous cyclical pulsed abnormal glow discharge (PAGD) will occur, the cathode being of sufficiently robust construction to enable it to withstand sustained PAGD and erosion resulting therefrom without disruption or substantial thermionic emission, the surface of the cathode facing the anode being of a metal and having an area which promotes auto-electronic emission at much lower currents than predicted by the Fowler-Nordheim field emission theory, and the minimum separation of the cathode from the anode being at least about 2 cm.
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18. A method of operating a cold cathode vacuum discharge tube in a pulse generator, the tube having a metallic cathode with extended surface area facing an anode and spaced therefrom sufficiently to allow a plasma eruption from the cathode associated with an abnormal glow discharge to occur without reaching the anode to form a continuous vacuum arc discharge channel, the area and metal of the cathode being selected to promote low field emission at much lower current densities than predicted by the Fowler-Nordheim vacuum arc discharge region law, while withstanding repeated abnormal glow discharges without substantial thermionic emission, connecting a circuit including a continuous direct current source between the anode and the cathode, the source having an open circuit potential and initial current capacity sufficient to initiate an abnormal glow discharge from the cathode and drive the discharge tube into a negative resistance region of abnormal glow discharge, and an impedance sufficient to ensure that the potential across the tube falls below that necessary to sustain the abnormal glow discharge before a vacuum arc discharge can be established.
Specification