Electric Parameters of the D.C. Carbon Arc
The basic electric parameters of an arc discharge are the current strength (i) and the voltage drop across the gap (V). Both quantities can be measured without difficulty. In general, a relationship between V and i such as shown graphically in Fig. 3.1 is found; clearly Ohm’s law is not obeyed: for a given value of the electrode distance (l) the arc voltage decreases as the current rises. The voltage-current curves lie higher for larger l. With carbon electrodes the voltage suddenly drops as the current exceeds a certain minimum value, which is accompanied by acoustic hissing (Zischen) of the arc.
KeywordsField Strength Power Dissipation Series Resistance Metal Vapour Current Strength
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