Method of generating plasma in a plasma-arc torch and an arrangement for effecting same
US4564740A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 30, 1983 |
| Grant date | Jan 14, 1986 |
| Priority date | — |
| Expiry date | Dec 30, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05H1/3484
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
The proposed method relates to the ionization of plasma-generating gas in a ilot arc before being supplied to the electrode region, thus generating charges in this electrode region, the charges promoting dispersion of an arc spot. For this purpose, an electrode assembly is provided within the plasma-arc torch, which electrode assembly comprises a hollow tungsten electrode and a solid electrode of the same metal, the solid electrode being radially spaced from the hollow electrode. Both electrodes are put in an electric power circuit, whereby an arc is initiated between the electrodes when switching on the electric circuit, plasma being generated in the arc, which plasma serves to start the main arc and provides for dispersion of the arc spot over the surface of the hollow electrode. This decreases the current density in the arc spots and, hence, minimizes electrode erosion. Such an arrangement provides for the nozzle to be electrically insulated from the electrodes and, therefore, protected against harmful damage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.