Circuit configuration for the recognition of a plasma

摘要

The invention relates to a circuit configuration for the recognition of a plasma which is supplied with energy by means of an ac current of preset frequency. This ac current is detected by way of a suitable sensor and feeds to a highpass filter. This highpass filter permits those frequencies to pass through which lie above the preset frequency. The output signal of the highpass filter is rectified through a rectifier, freed of its residual ripple through a lowpass filter, and supplied to an evaluation device.