Nonlocal collisionless power absorption using effective viscosity model in inductively coupled plasma discharges

Abstract

Effective viscosity model for inductively coupled plasma (ICP) discharges has been used to calculate the power absorbed inside ICP discharges. It is found that it can be used to calculate collisionless heating, which is a warm plasma effect. The validity of effective viscosity model has been checked by comparing it with kinetic model for warm ICP discharges. For very small plasma lengths, the results of both models are the same. At intermediate lengths where bounce resonance heating is important, results of the two models are not the same. Bounce resonance length given by effective viscosity model does not match very well with that given by the kinetic model. It shows that bounce resonance heating cannot be taken care of accurately using the effective viscosity model. For large plasma length, when driving frequencies are low, power absorbed calculated using the kinetic model is more than that calculated by the effective viscosity model. For high driving frequencies, power absorbed calculated using the kinetic model is less than that calculated by the effective viscosity model. The best match between the results of two models (for large plasma length) is obtained if the combination of plasma density, electron temperature, driving frequency, and speed of light is such that the relation K=ωpvth/ωc≃1 holds. It is concluded that computationally less extensive effective viscosity model can be used to estimate power absorption in ICP discharges by calibrating it with the help of computationally intensive kinetic model. Once calibration is done a lot of computational effort can be avoided by using effective viscosity model instead of kinetic model.