Inductively Coupled Plasma
The first version of a true Inductively coupled plasma (ICP) torch was developed by Reed in 1961 who meant to use it for growing single crystals of stabilized zirconia and other refractory materials. Nevertheless, ICP soon began to attract attention for spectrochemical analysis as an alternative to flame and DC plasma sources. This was due to the fact that ICP could provide significantly higher temperatures, higher electron number densities, minimized matrix interferences (in contrast to flames), absence of contaminating electrodes (as opposed to DC plasmas), and multielement analysis capabilities. Nowadays, ICP-based spectrometry (ICP-OES and ICP-MS) is the single most important method for trace and ultra-trace element analysis in various fields. In addition, industrial high-power ICP torches are now used for powder processing, spherodization/densification (through in-flight melting of metallic, metal oxide, and refractory powders followed by gradual cooling), purification, and reactive evaporation for nucleated nano-powders, as well as synthesis and spray of ultra- fine and pure refractory powders.