Process, apparatus and coating plant for long-term stable evaporation

A method of uniformly evaporating an evaporation material (3) into an evaporator (2), wherein the evaporating material (3) is heated and evaporated in the evaporator (2) via a heating device (4) and the heat output of the heater (4) in response to a change in weight of the evaporator (2) is adjusted, characterized in that the heating device (4) comprising an electron source and the heating of the evaporation material (3) by means of electron impact, by the kinetic energy of from an electron source, which is operated as a cathode, emitted and is converted operated as an anode evaporator (2) accelerated electrons upon striking the evaporator in thermal energy that a change in position as a change of the distance between the evaporator (2) and heating means (4) due to the weight change of the evaporator (2) with respect to the heating means (4) by means of a movable bearing (5), wherein the heating power of the electron source depends on the distance between the evaporator (2) and electron source (4) by arise over the field strength of the applied front of the cathode electric field as a function of the distance of the extracted electron current and hence the heating power of the electron source (4) and that on the evaporator (2) the evaporating material (3) is heated.