Effect of electron thermal motion on plasma heating in a magnetized inductively coupled plasma

Abstract

Power absorbed inside the magnetized inductively coupled plasma (MICP) is calculated using three different warm MICP models and is then compared with the result of the cold MICP model. The comparison shows that in the propagating region (ω<∣Ωe∣), under the cavity resonance conditions, warm plasma heating Swarm is significantly less than the cold plasma heating Scold, unless the distance traveled by the electrons due to their thermal motion, during the effective wave period, becomes significantly less than the wavelength of the cavity wave. Furthermore, in the propagating region, when ω≈∣Ωe∣, there appears a valley on the plot of η(ω)=Swarm∕Scold versus ω showing the negative effect of electron thermal motion on plasma heating. This valley widens and gets smoother with an increase in the plasma length. In the nonpropagating region (ω>∣Ωe∣), the maximum value of η(ω) exists when ω−∣Ωe∣≈vth∕δ, showing that, in the presence of the external magnetic field, the thermal motion of the electrons leads to a Doppler shift of the frequencies, at which collisionless heating is the dominant mode of electron heating. Furthermore, in the nonpropagating region, when ω≈∣Ωe∣, the skin depth of the right circularly polarized electric field decreases with magnetic field. This decrease in the skin depth results in an increase of collisionless heating under the Doppler-shifted wave particle resonant condition of ω−∣Ωe∣≈vth∕δ. It is also observed that, for large plasma length, the results of all the three warm MICP models are consistent with each other.