Bremen 2017 – wissenschaftliches Programm
P 23.14: Poster
Mittwoch, 15. März 2017, 16:30–18:30, HS Foyer
A Computationally Assisted Spectroscopic Technique to measure secondary electron emission coefficients in technological RF plasmas — •Birk Berger1,2, Manaswi Daksha1, Edmund Schüngel1, Mark Koepke1, Julian Schulze1,2, Ihor Korolov3, Aranka Derzsi3, and Zoltán Donkó3 — 1Department of Physics, West Virginia University, Morgantown, USA — 2Institute for Electrical Engineering, Ruhr-University Bochum, Germany — 3Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary
A Computationally Assisted Spectroscopic Technique to measure secondary electron emission coefficients (y-CAST) in capacitively coupled radio-frequency plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of Phase Resolved Optical Emission Spectroscopy and particle-based kinetic simulations. In such plasmas the spatio-temporally resolved electron-impact excitation rate features two distinct maxima adjacent to each electrode at different times within each RF period. While one maximum is the consequence of the energy gain of the electrons due to sheath expansion, the second maximum is produced by y-electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the adjacent sheath. Due to the different excitation mechanisms the ratio of the intensities of these maxima is very sensitive to y, which allows for its determination via comparing the experimentally measured excitation profiles with corresponding simulation data obtained with various y-coefficients. This diagnostic is tested here in a geometrically symmetric reactor, for stainless steel electrodes and argon gas.