Abstract
The characteristics of the anode drop were studies through measuring only the arc voltage of the constricted TIG arc burned between tungsten electrode (cathode) and base metal (anode) of various materials of different heat conductivities. To study the cathode drop, we estimated the temperature distribution along the electrode by measuring the radiation energy from the pure and 2% thoriated tungsten electrode surface.
The following facts were made clear;
(1) The anode drop is influenced by the temperature of the anode. It decreases when anode is heated to high temperature. For material of higher thermal conductivity, the anode drop is higher for given current.It decreases as the current increase tending to zero.
(2) When the cathode is heated high by some other method (Joule's heating), the cathode drop decreases to low value and results in a negative cathode power.
(3) Cathode drop is affected by the work function of the substance added to the cathode. The amount of the change of cathode drop predominates over the amount of the change of work function. Therefore the cathode power is affected remarkably by a small change of work function of material added to cathode.
