Technique for the chemical analysis of trace elements in a wide variety of materials, using a source that depends on the interaction between the magnetic field of an oscillating radio-frequency current and the charged species present in the plasma. Argon gas is passed through the field producing a toroidal (doughnut-shaped) plasma at temperatures of over 5000 °C. The sample is introduced as an aerosol into the gas and is vaporized and atomized in the plasma. The source has a monochromator (a means of selecting a single frequency) and a readout system. It has low limits of detection for most elements, and is a very rapid technique.