It is generally considered that plasma is the fourth state of matter. Indeed, in the normal state, a gas, composed of electrically neutral molecules, does not conduct electricity. By subjecting a gas to the action of an elevated temperature, it is possible to dissociate the molecules that compose it, and then ionize the gas, that is to say to separate the negative charge carrier electrons and the positively charged nucleus . The application of an electrical potential gas allows to pass an electrical current between the anode and cathode, and thus maintain an electric arc.

The high frequency arc is maintained by a low voltage power source in a flow of plasma gas. High energy supplied by the source can reach a temperature of approximately 50 000°C at the cathode. Nevertheless, the temperature will drop quickly during projection. Substrate never heat up above 120°C.

The plasma gas is subjected to a considerable expansion (more than 100 times its volume). It is blown at high speed by the anode nozzle. On the outside of the nozzle, it gradually returns to its normal state.
However, it remains at high temperature and speed obtained for projecting at very high kinetic energy of high melting alloys.