Berlin 2014 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 5: Low Temperature Plasmas I
P 5.6: Vortrag
Montag, 17. März 2014, 18:10–18:25, SPA HS201
E-H-mode transition in inductively coupled RF oxygen discharges. — •Thomas Wegner, Christian Küllig, and Jürgen Meichsner — Institute of Physics, University of Greifswald
The mode transition of a planar inductive coupled radio frequency (ICRF) discharge in oxygen was detailed investigated by several diagnostics.
Firstly, the optical emission of atomic oxygen was measured phase and space resolved (PROES).
The optical exication rate patterns from rf sheath heating and electric field reversal in the E-mode change to two excitation rate patterns in the first and second half of the RF cycle in the H-mode, respectively.
In particular, the electric field reversal reveals a high electronegativity in the E-mode.
All in all, the analysis of the excitation rates enables the distinction of the operation modes.
Addionally, the gas temperature was determined by measuring the emission of the atmospheric A-band of the oxygen molecule at 760 nm.
In the E-mode, the gas temperature is comparable to room temperature (300 K) and increases up to 600 K in the H-mode.
The line integrated electron density, measured by microwave interferometry, increases during the E-H-mode transition up to two orders of magnitudes from 1015 to 1017 m−2 depending on the total gas pressure.
Using the electron density, gas and electron temperature the electron impact ionization rate was calculated.
The behavior of the electron impact ionisation rate during the E-H-mode transition provides an indication for a decreasing electronegativity.
//Funded by the DFG CRC/Transregio 24, project B5.