Electric arc

Electric arc (synonym: Valitova arc, arc Petrov, an electrical arc) is a type of electric discharge, which bit phenomena are concentrated in a narrow bright luminous channel going from one electrode to the other. The ionizing effect is achieved by the collision of gas particles with electrons, breaking away from the end of the electrode, carrying a negative potential (when the AC power both electrodes alternately become negative). The temperature at the end of a negative carbon electrodes at atmospheric pressure reaches 4000 degrees positive 3600 degrees; AC ends of both carbon electrodes have a temperature of about 3,600 degrees.
Electric arc occurs as in the open air (the spotlight)and in gas-filled (mercury vapor, argon, neon) tubes (mercury-quartz, fluorescent lamps).