US Patent 7453566 Hybrid plasma element monitor

Hybrid plasma monitor. A ground electrode is spaced apart from a high voltage electrode supporting an electric discharge therebetween to generate a plasma. The ground electrode and the high voltage electrode form an annular region into which a sample is introduced for generating a plasma. Microwave radiation couples into the plasma to sustain the plasma. A light detector such as a spectrometer receives light resulting from atomic emissions from the sample to analyze elements in the sample.