A plasma generator with a hollow electrode connected to a venturi pump which draws a portion of the gas out of the arc chamber in a direction away from the workpiece to stabilize a molten-metal pool formed by the plasma generator. The withdrawn portion of the gas is recycled to the region around the plasma arc between the arc chamber and the workpiece.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my application Ser. No. 721,843 filed Apr. 16, 1968 and issued July 20, 1971 as U.S. Pat. No. 3,594,609.
An active gas plasma arc torch and a method of operating the same, said torch including a rod-shaped cathode, a first gas passage formed around said cathode to feed a protecting gas or shielding gas, a second gas passage formed around said first gas passage to feed a plasma gas and a constricted port for discharging the plasma gas, characterized in that at least a part of the shielding gas which flows out from the first gas passage is removed from the inside of the torch at the position short of said constricted port of the torch, whereby the working quality and the working speed are substantially improved while the rod-shaped cathode is satisfactorily protected by the shielding gas.
