Hannover 2016 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 24: Low Temperature Plasmas II
P 24.2: Fachvortrag
Donnerstag, 3. März 2016, 15:00–15:25, b305
Electronegativity during E-H transition in inductively coupled RF oxygen discharge — •Thomas Wegner, Christian Küllig, and Jürgen Meichsner — Institute of Physics, University of Greifswald
The E-H transition of an inductively coupled radio frequency oxygen discharge (ICP) is investigated using enhanced plasma diagnostics.
Therewith, the positive ion saturation current, electron density and temperature, gas temperature, ground state (O2(X3Σg−)) and metastable (O2(a1Δg)) density are measured with high resolution in RF power input during the E-H transition.
Further, the RF sheath dynamics are although studied.
The attenuation of the RF sheath heating and especially the vanishing electric field reversal during the E-H transition indicates an decreasing electronegativity defined as the ratio between the negative atomic ion (O−) and electron density.
Additionally, the electron density peak due to collisional detachment of the negative ions with metastables in the early afterglow of a pulsed RF discharge gives information about the negative atomic oxygen ion density, too.
Beside of these experimental findings, analytical calculations using a set of particle balance equations provide the negative ion density and consequently the electronegativity.
The measured parameter which are mentioned above are used as input parameter for these calculations.
The experimental investigations as well as the analytical calculations show that the electronegativity drops drastically from about 25 to 0.2 during the E-H transition.
//Funded by the DFG CRC/Transregio 24, project B5.