The application of low‐energy molecular‐beam techniques to the analysis of the neutral (metastable and ground‐state) particles emitted by a thermal plasma is described. The technique is illustrated with the use of an apparatus that contains a rotating slotted‐disk velocity analyzer and an inhomogeneous‐field deflecting magnet. The beam source is a hot‐cathode low‐voltage continuous discharge in a rare gas. With this apparatus the Lande´gfactor was found to be 1.51 ± 0.01 for Ne3P2and 1.50 ± 0.02 for Ar3P2, in accord with theory. In addition, measurement of the velocity distributions of the two Ne metastable atoms (3P0and3P2) demonstrated that they could be characterized by Maxwell‐Boltzmann distribution functions with different temperatures for the two states.