Plasma in nature (Stars, Flashes) is usually connected to extremely high temperatures. Also in case of a technically produced plasma by gas discharge very high temeperatures are observed caused by a high electrical current. If a gas is ionisized by electromagnetic HF-stimulation the plasma remains cold or the temperature will only slightly be elevated. Under HF-stimulation (40 kHz - 13,56 MHz) there is a difference between temperature of ions and of electrons. Electrons are hot because they are able to follow the high frequency of the field while the much heavier ions remain in rest.