Verfahren zur kontinuierlichen Messung der stofflichen Zusammensetzung des Dampfes einer Schmelze oder eines zu verdampfenden Materials im Vakuum

The invention relates to a process for the continuous measurement of the material composition of the vapour above a melt in a vacuum, in particular in electron beam melting and electron beam vaporization. Known processes such as analyzing melt samples, X-ray monitoring and using optical emission, have not achieved high accuracy of the measuring result. It is proposed to make continuous measurement possible by the use of axial canons. According to the invention, the ratio between the vapour pressure above the melt and the beam potential is adjusted so that at least 3% of the electron beam power is absorbed by the vapour. The intensity of at least one characteristic line of the emission spectrum of a material component of the melt is then measured. One or several operating parameters of the electron canons are controlled so that the intensity of this characteristic line remains constant