Decay of an inductively coupled argon plasma above the load coil

Abstract

Radial temperature and electron number density profiles of an argon ICP have been theoretically calculated above the load coil with observation heights of from 0 to 20 mm, taking into account thermal conduction, ambipolar diffusion, collisional and radiative recombination, ionisation, axial convection, compression and expansion processes. The results of the theoretical calculations indicate that both thermal conduction and ambipolar diffusion processes are important for plasma decay above the load coil. Compression heating of the hot plasma region caused by a decrease in the temperature with an increase in observation height has a large influence on sustaining the ICP. The possible importance of a radial convection process for the peaking of temperature and electron number density towards the plasma axis, and therefore for plasma decay above the load coil, is also discussed.