3. Instrumentation

3.1 Plasma generation

For chemical analysis, we generally use a noble gas plasma, whose properties are relatively independent of the sample. The noble gas is ionized by electrons accelerated by an electromagnetic field. These electrons are created beforehand by an auxiliary discharge. They collide with the atoms of the noble gas, ionizing them.

Plasmas are classified according to the type of electric field: continuous field, high-frequency field or microwave field. In all cases, an electrical generator is required to create the field. Although the DC field was widely used in the 1970s in the form of arc plasma (Direct Current Plasma or DCP), it was later superseded by the high-frequency field. This field is supplied by a generator through an inductor, leading...