DC ARC PLASMATRON AND METHOD OF USING THE SAME

The present invention concerns a DC arc plasmatron which is a plasma generator at the atmospheric pressure having a structure suitable for improving chemical activity of plasma. The DC arc plasmatron according to the invention comprises a rod cathode 110 connected to a DC power supply 1000, and formed to be positioned close to a nozzle to be a negative; a nozzle anode 120 formed on the nozzle to be a positive, being an opening to inject plasma into a functional gap 150 and having an anode inlet 122, wherein the plasma is created by gas discharge for forming the plasma between the cathode and the anode; a functional anode gap formed on the nozzle to be a positive so that either a function gas or a gas mixture is supplied on some part of the passage of the anode to make it react with the plasma forming gas through the nozzle inlet; and a gas supply unit for supplying a plasma forming gas flowing through the nozzle anode from the side of the rod cathode. The anode comprises an anode inlet 122 as an inlet of the functional gap 150; an anode outlet 125 as an outlet of the functional gap 150; the functional gap 150 formed as a disk shaped space 300 communicating with a part of the passage between the anode inlet 122 and the anode outlet 125; a gas collecting chamber 500 formed with a chamber member communicating with the disk shaped space 300; and a functional process gas conduit 600 communicating with the gas collecting chamber 500 and formed so that either the functional gas or a gas mixture can be supplied. The functional gap 150 is formed to have a height G to be 0.3A to 3A with respect to the diameter A of the anode inlet 122. The anode outlet 125 is formed to have a diameter D to be 0.3A to 3A with respect to the diameter A of the anode inlet 122. A method of using the plasmatron according to the invention comprises the steps of: a first step of selecting a proper functional gas, supplying it to the functional process gas conduit 600 and thereafter supplying a plasma forming gas in the space around the rod cathode 110 and the anode 120; a second step of supplying cold water and operating the DC power supply 1000 connected to the plasmatron; a third step of initiating arc discharge by applying high voltage across the rod cathode 110 and the anode 122, and activating the plasma forming gas and the functional gas by interaction therebetween while the plasma forming gas is excited and heated; and a fourth step of, after fixing a process variable to a proper le