If energy is continuously added to a piece of matter, its temperature rises and it usually changes from a liquid to a gaseous state. If the energy supply is continued, the kinetic energy of the elementary constituents increases with the temperature to a point where the collision of the gas molecules and the atoms breaks up the atomic shell of electrons. Negatively charged electrons and positively charged ions are formed.

This mixture of neutral, positively and negatively charged particles is known as plasma, which is electrically conductive due to its high temperature.

Plasma, also known as the 4th state of matter, exhibit unusual new properties due to the superposition of many different atomic physical effects. Plasmas can be easily influenced by external electric and magnetic fields, making them extremely controllable. Because of their high energy content, they enable processes that cannot take place in other states of matter. These properties make plasma a particularly powerful and extremely flexible tool for many industrial applications.

In a plasma torch, a direct voltage (DC) is first applied between the negative electrode and the nozzle, which is also applied between the electrode and the electrically conductive workpiece. By generating high-voltage pulses in parallel with the DC voltage between the electrode and the nozzle, a low-energy plasma jet, known as an pilot/auxiliary arc, is created inside the plasma torch. The plasma gas is dissociated (molecules are broken down into atoms) and ionised (electrons leave the electron shell) and emerges from the nozzle as a bright cone of light, making the space between the electrode and the workpiece electrically conductive.