Plasmareaktor

In a plasma reactor for producing and maintaining a plasma, a cavity resonator (11) is provided, having a cross-section which is tapered in the vertex areas (13, 16). The wall (14) of the cavity resonator (11) is closed at the vertex areas (13, 16) to such an extent that an excited field mode has principle maxima (15, 31) in the area of the cross-section tapers, said principle maxima having a maximum field strength which is excessive compared with the field strengths of adjacent secondary maxima. In the area of the principle maximum (31), a reaction unit (18) is provided with a substrate to be processed (21) which can be coated from the gas phase of the plasma (32). Due to the field strength distribution resulting from the cavity resonator (11) of the specified design, process parameters such as gas pressure and injected electromagneitc capacity are selectable mainly independently of each other when the plasma is stable without the plasma (32) in the area of the secondary maxima being ignited undesirably. Moreover, the objective is to obtain uniform processing of the substrate (21) by means of a relatively homogenous field strength distribution in the principle maximum (31) supporting the plasma (32).