# US 4,394,622 A · High voltage coaxial switch

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- Number: US 4,394,622 A
- Document ID: US4394622A
- Status: Granted
- Kind: A
- Application number: 06/269,457
- Filed: 1981-06-03
- Granted: 1983-07-19
- Earliest claimed: 1981-06-03
- Inventors: John P. Rink
- Web page: https://patentgrep.com/patent/US4394622A

## CPC

- H01J 17/38: Cold-cathode tubes
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure.

## Claims

### Claim 1

A high voltage coaxial switch comprising:
a circular cross-sectioned cylindrical cathode;
a thin walled hollow circular cross-sectional cylindrical inner electrode coaxially surrounding said cathode;
a hollow circular cross-sectional cylindrical outer electrode coaxially surrounding said inner electrode;
means for facilitating evacuation of the region between said cathode and said inner electrode;
means for facilitating provision of a gas to the region between said inner electrode and said outer electrode;
means for providing a high voltage charge to said outer electrode;
means for connecting a load to said inner electrode;
and
means for providing a high voltage pulse between said cathode and said inner electrode to cause electrons to be emitted from said cathode and accelerated toward said inner electrode with sufficient quantities of electrons passing therethrough to cause secondary electron emission and a volumetric discharge in the region between said inner electrode and said outer electrode whereby a high voltage charge on said outer electrode is discharged to said inner electrode and through a load connected thereto.

### Claim 2 (depends on 1)

The high voltage coaxial switch according to claim 1 wherein said circular cross-sectional cylindrical cathode is a cold cathode.

### Claim 3 (depends on 2)

The high voltage coaxial switch according to claim 2 wherein said cold cathode has a plurality of points thereon to aid in electron emission therefrom.

### Claim 4 (depends on 3)

The high voltage coaxial switch according to claim 3 wherein said plurality of points on said cold cathode are positioned so as to induce a relatively uniform electron emission in the region between said cold cathode and said inner electrode.

### Claim 5 (depends on 2)

The high voltage coaxial switch according to claim 2 wherein said cold cathode is a solid circular cross-sectional cylindrical cold cathode.

### Claim 6 (depends on 5)

The high voltage coaxial switch according to claim 5 wherein said solid circular cross-sectional cylindrical cold cathode is a solid brass circular cross-sectional cylindrical cold cathode.

### Claim 7 (depends on 2)

The high voltage coaxial switch according to claim 2 wherein said thin walled hollow circular cross-sectional cylindrical inner electrode is fabricated from aluminum.

### Claim 8 (depends on 2)

The high voltage coaxial switch according to claim 2 wherein said thin walled hollow circular cross-sectional cylindrical inner electrode has a wall no greater than approximately one-sixteenth inch thick.

### Claim 9

A high voltage coaxial switch for discharging a highly charged electrode through a load, said high voltage coaxial switch comprising:
a solid brass circular cross-sectional cylindrical cold cathode;
an aluminum thin walled hollow circular cross-sectional cylindrical inner electrode coaxially surrounding said cold cathode, said inner electrode connected to the load;
a highly charged aluminum hollow circular cross-sectional cylindrical outer electrode coaxially surrounding said inner electrode;
means for maintaining an evacuated region between said cold cathode and said inner electrode;
means for maintaining a gas filled region between said inner electrode and said outer electrode; and
means for providing a high voltage pulse between said cold cathode and said inner electrode to cause electrons to be emitted from said cold cathode and accelerated toward said inner electrode through said evacuated region maintained therebetween with sufficient quantities of electrons passing therethrough to cause secondary electron emission and a volumetric discharge in said gas filled region maintained between said inner electrode and said outer electrode whereby said highly charged outer electrode is discharged to said inner electrode and through the load connected thereto.

### Claim 10 (depends on 9)

The high voltage coaxial switch according to claim 9 wherein said solid brass circular cross-sectional cylindrical cold cathode has a plurality of points thereon to aid in electron emission therefrom.

### Claim 11 (depends on 10)

The high voltage coaxial switch according to claim 10 wherein said plurality of points on said cold cathode are positioned so as to induce a relatively uniform electron emission in said evacuated region between said cold cathode and said inner electrode.

### Claim 12 (depends on 9)

The high voltage coaxial switch according to claim 9 wherein said means for maintaining a gas filled region maintains an air filled region between said inner electrode and said outer electrode.