Three different types of generators for plasma jet have been designed; they are stabilized by running water, argon, or nitrogen gas respectively.
In the type of using running water, the anode is a carbon rod and the cathode a carbon disk with a circular hole. Water is injected tangentially into a glass cylinder making a vortex flow. The arc is pinched by the so-called “thermal pinch”. The plasma jets out from the hole of the cathode. The mean arc current and voltage are 400 amperes and 80 volts respectively. Details of electrical characteristics have not been obtained as the disintegration of the anode is so fast.
In the generator of plasma jet, in which argon is used for cooling, tungsten for the cathode and copper for the anode, both being cooled by running water, stabilized arc plasma and jet are obtained. The electrical characteristics-the voltage dependences on discharge current, diameter of the pinched plasma and distance between electrodes-have been measured.
The structure of the nitrogen plasma jet generator is similar to that of the argon type except an additional outlet of the cooling gas which is provided in order to stabilize the arc.
