In the plasma of a gas discharge, very high temperatures occur. This is due to the power dissipation from the ohmic resistance, and the high current flow. With high-frequency excitation in low-pressure plasma. the temperature is increased only very slightly. This is because the ions cannot follow the high frequency of the alternating field due to their mass inertia, i.e. they practically retain their molecular motion. Since the temperature of a medium is caused by the motion energy of the molecules and atoms, however, the temperature of the plasma practically is not increased at all, compared to the non-excited gas. The temperature load in the low-pressure plasma with high-frequency excitation therefore also permits the treatment of temperature-sensitive substrates, including practically all plastics. Only electrically conductive substrates based on induced currents (as in microwave ovens) are strongly heated in low-pressure plasma.