One-dimensional time-dependent fluid model of a very high density low-pressure inductively coupled plasma

• Published in: Journal of applied physics 2015-12, Vol.118 (24)
• Main Authors: Chaplin, Vernon H., Bellan, Paul M.
• Format: Article
• Language: English
• Subjects: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Ambipolar diffusion; antennas; Applied physics; Argon; atomic model; Computer simulation; diffusion; Electron density; Electron energy; Energy budget; excited states; experiment design; Inductively coupled plasma; Ionization; Mathematical models; Plasma; Plasma density; plasma transport; Populations; Radio frequency; Temperature dependence; Time dependence; Two fluid models; two-fluid model
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4938490

A time-dependent two-fluid model has been developed to understand axial variations in the plasma parameters in a very high density (peak ne≳5×1019 m−3) argon inductively coupled discharge in a long 1.1 cm radius tube. The model equations are written in 1D with radial losses to the tube walls accounted for by the inclusion of effective particle and energy sink terms. The ambipolar diffusion equation and electron energy equation are solved to find the electron density ne(z,t) and temperature Te(z,t), and the populations of the neutral argon 4s metastable, 4s resonant, and 4p excited state manifolds are calculated to determine the stepwise ionization rate and calculate radiative energy losses. The model has been validated through comparisons with Langmuir probe ion saturation current measurements; close agreement between the simulated and measured axial plasma density profiles and the initial density rise rate at each location was obtained at pAr=30−60 mTorr. We present detailed results from calculations at 60 mTorr, including the time-dependent electron temperature, excited state populations, and energy budget within and downstream of the radiofrequency antenna.