welding arc

An electric arc is a sustained and intense gas discharge phenomenon between two charged conductors.

1. Formation of an Electric Arc

(1) Short Circuit Between Electrode and Workpiece

During a short circuit, individual contact points with concentrated current are heated by resistance heat Q=I²Rt, resulting in a very high electric field strength in the extremely small air gap.

Results:
① A small number of electrons escape.

② Individual contact points are heated, melted, or even evaporated and vaporized.

③ Many metal vapors with low ionization potentials appear.

(2) Maintaining an Appropriate Distance by Lifting the Electrode

Under the influence of thermal excitation and a strong electric field, the negative electrode emits electrons that move at high speed and direction, colliding with neutral molecules and atoms to excite or ionize them.

Results: The gas in the air gap is rapidly ionized. Through collisions, excitation, and recombination of positively and negatively charged particles, its energy is converted, emitting light and heat.