Abstract: A process and a device for coating the inner surface of a greatly arched, essentially dome-shaped substrate by CVD are described. In the process, the reaction gases, which contain the layer-former molecules, are conveyed into the reaction chamber containing the substrate(s) to be coated, through at least one gas inlet, placed facing the vertex of the dome at a distance from the surface to be coated. Deposition of the layer material on the substrate is brought about in a way known in the art by producing a reaction zone on the inner surface of the substrate to be coated. According to the invention, the reaction gases do not, as is usual for known processes, flow slowly into the reaction chamber. Instead, for production of a uniform coating, the reaction gases are introduced into the reaction chamber at a high speed such that the product of Reynolds number, R, of the gas jet in or in the immediate vicinity of the gas inlet and the distance, h, between the gas inlet and the dome vertex is:400<R.times.

Abstract: An apparatus supplies CVD coating devices with coating gas and includes an intermediate reservoir for accommodation of the gaseous coating material arranged between a storage tank and a coating device. The volume of the reservoir is set to a predetermined, maximum pressure change in the intermediate reservoir upon withdrawal of the mass of gas required for a coating step. The intermediate reservoir can be connected to a gas recovery station.

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.

Abstract: An arrangement for coupling microwave energy with a reaction chamber, including electrically stable tuning and being, within limits, tolerant against changes in critical dimensions and power fluctuations. A coaxial line between a hollow waveguide and the reaction chamber is of such a structure that it forms, at least together with the reaction chamber, a loss resonator for the microwave frequency employed. The coaxial line can comprise an absorber or, alternatively, can be made of a poorly conductive material. There is also the possibility of downgrading the quality of the resonator by leaving an annular gap between a metal plate and an outer conductor section.