Abstract: A process and an apparatus for economically igniting microwave plasmas wherein no undesirable reaction products in the reaction chamber impair the quality of cladding produced thereby. The plasma is ignited on the gas outlet side of the reaction chamber by means of a high voltage that is applied at least for a short period of time. High-frequency pulses or low-frequency high voltages with frequencies in the range from 10 to 100 kHz are utilized. The high voltage is synchronized with the microwave pulses. According to a further process, the microwave pulses are excessively increased for a short time at least at their beginning. Also periodic excessive increases of the microwave pulses are possible A switchable high-voltage source is connected by way of a delay member and a current supply unit to the microwave device The output of the switchable high-voltage source is applied to the gas discharge line of the reaction chamber.