One-dimensional time-dependent fluid model of a very high density low-pressure inductively coupled plasma
A time-dependent two-fluid model has been developed to understand axial variations in the plasma parameters in a very high density (peak n_e ≳5×10^(19) 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 n_e (z,t) and temperature T_e (z,t), and the populations of the neutral argon 4s metastable, 4s resonant, and 4pexcited 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.
© 2015 AIP Publishing LLC. Received 22 August 2015; accepted 10 December 2015; published online 28 December 2015. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Fusion Energy Sciences under Award Nos. DE-FG02-04ER54755 and DE-SC0010471 and by the National Science Foundation under Award No. 1059519. V. H. Chaplin acknowledges support by the ORISE Fusion Energy Sciences Graduate Fellowship.
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