A multiple cathode DC arc plasma generator arrangement is used in connection with a single anode for thermal arc plasma processing of materials. A nozzle is provided to introduce a gas in approximately the center of the multiple cathodes, towards the anode. The nozzle injects the gas into the center of the plasma column generated between the cathodes and anode to stabilize such arc and affect the self-induced electrode jets. This provides control of the heat transfer to the anode and permits feeding of particulate matter into the core of the plasma column to enhance inflight processing (melting and/or chemical reaction) of the matter. A set of gas nozzles positioned radially about the anode may be employed for feeding of particulate matter at the anode surface.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of my co-pending U.S. patent application Ser. No. 655,340, filed Sept. 27, 1984 for a Multiple Arc Plasma Device with Continuous Gas Jet now abandoned.
The invention provides a plasma spray apparatus for spraying powdery or gaseous material. The apparatus comprises an indirect plasmatron for creating an elongated plasma torch. The powdery or gaseous material is axially fed into the plasma torch. The plasmatron comprises a cathode assembly, an annular anode member located distantly from the cathode assembly and a plasma channel extending from the cathode assembly to the anode member and having a zone with a reduced diameter located in the region of the plasma torch which is near to the cathode assembly. The plasma channel is delimited by the annular anode member as well as by a plurality of annular neutrode members which are electrically insulated from each other. The cathode assembly comprises a central insulating member arranged in a fixed position with regard to the plasma channel inlet nozzle and further comprises a plurality of cathode elements embedded in the insulating member.
An apparatus and method for the synthesis of ultra-free (submicron) ceramic carbides in a thermal plasma torch reactor using primarily silica, boron oxide, titanium dioxide or other oxides as metal sources and methane as a reductant. A plasma torch operated with both argon and helium as plasma gases and having methane as a primary carrier gas is connected to the plasma reactor for providing the heat necessary to carry out the reaction. A collection chamber with both interior and exterior cooling is connected to the reactor for quenching of the reactants. Cooling is provided to the torch, the reactor and the collection using coils, baffles and jackets.
A method for vapor deposition of diamond by effecting an arc discharge while feeding a discharge gas between an anode and a cathode of a thermal plasma chemical vapor deposition device, radicalizing a gaseous carbon compound by feeding the gaseous carbon compound into a generated plasma jet, and permitting the radicalized plasma jet to impinge on a substrate to be treated, whereby a film of diamond is formed on the substrate.
An improved vacuum arc coating apparatus is provided, having a reaction zone with a plasma channel defined within a series of aligned annular substrate holders, or between an outer wall of a chain of substrate holder blocks and the inner wall of the tube. The substrate holders thus act as a liner, confining an arc within the plasma channel. Carrier and plasma creating gases and the reaction species are introduced into the tube, and the deposition process may be carried out at a pressure between 10 Torr and 1000 Torr. Magnetic coils may be used to create a longitudinal magnetic field which focuses the plasma column created by the arc, and to create a transverse magnetic field which is used to bias the plasma column toward the substrates. Substrates can thus be placed anywhere within the reaction zone, and the transverse magnetic field can be used to direct the plasma column toward the substrate, or the tube itself can be rotated to pass the substrate through the plasma column.
An apparatus for a vapor deposition of diamond by: effecting an arc discharge while feeding a discharge gas between an anode and a cathode of a thermal plasma chemical vapor deposition device; radicalizing a gaseous carbon compound by feeding the gaseous carbon compound to a generated plasma jet; and permitting said radicalized plasma jet to impinge on a substrate to be treated, whereby a film of diamond is formed on said substrate.
