Arc initiation in cathodic arc plasma sources
US6465793B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 31, 2000 |
| Grant date | Oct 15, 2002 |
| Priority date | — |
| Expiry date | Mar 31, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/022
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A “triggerless” arc initiation method and apparatus is based on simply switching the arc supply voltage to the electrodes (anode and cathode). Neither a mechanical trigger electrode nor a high voltage flashover from a trigger electrode is required. A conducting path between the anode and cathode is provided, which allows a hot spot to form at a location where the path connects to the cathode. While the conductive path is eroded by the cathode spot action, plasma deposition ensures the ongoing repair of the conducting path. Arc initiation is achieved by simply applying the relatively low voltage of the arc power supply, e.g. 500 V-1 kV, with the insulator between the anode and cathode coated with a conducting layer and the current at the layer-cathode interface concentrated at one or a few contact points. The local power density at these contact points is sufficient for plasma production and thus arc initiation. A conductive surface layer, such as graphite or the material being deposited, is formed on the surface of the insulator which separates the cathode from the anode. The mechanism of plasma production (and arc initiation) is based on explosive destruction of the la…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.