Study of the Electromagnetic Coupling in an Inductively Coupledplasma Torch at Atmospheric Pressure

This work is devoted to study the behaviour of an inductively coupled plasma torch using argon,hydrogen and oxygen at atmospheric pressure.Thermal plasmas are generally used to form highly reactive species and to transfer enthalpy.Precise characterisation of the plasma behaviour is thus relevant to evaluate chemical and thermal effects of the plasma.For equivalent configurations in terms of torch geometry and gas flows,a transition between two different coupling modes is identified affecting atomic species distribution and energy transmitted to a copper target.These two modes are affected by total electrical power input and oxygen and hydrogen flow rates,showing up hysteresis behaviour.Electrical current and frequency progress are analysed to highlight the transition between the two coupling modes.Optical spectroscopy is used to measure temperature profiles and radial atomic oxygen concentration profiles for different coupling modes.We observe that-depending on the coupling mode-temperature profile,atomic species distribution as well as the power transmission to a copper target are affected.