Design of a fixed-frequency impedance matching network and measurement of plasma impedance in an inductively coupled plasma for atomic emission spectroscopy

The design of a fixed frequency impedance matching network for inductively coupled plasma-atomic emission spectroscopy (ICP-AES) is developed based upon an accurate model. Plasma impedance is determined by a substitution method in conjunction with the matching network model. The model is precise enough to allow the determination of electrical stresses on components of the circuit for design purposes. Variations of the plasma impedance caused by gas flow rate changes or by sample introduction are measured.Practical considerations in the design are made to ease ignition, to improve stability of the power transferred to the plasma, and to increase the efficiency of this power transfer. This has resulted in the production of a commercial matching network with power transfer efficiency of 86%.