Phasenaufgelöste emissionsspektroskopische Untersuchung der Besetzungsdynamik angeregter Zustände in Wasserstoff-RF-Entladungen (Volume 1) (English shop)

Time-resolved investigations of excited-state populations form the central focus of Timo Gans’s dissertation on hydrogen radio-frequency discharges.
The research examines the temporal evolution of electronically excited states in low-temperature plasmas using phase-resolved optical emission spectroscopy (OES).
Particular attention is given to capacitively coupled radio-frequency (CCRF) discharges and the interactions between electrons, ions, and neutral hydrogen particles.
A major objective is the development of spectroscopic techniques for determining collisional quenching coefficients of excited atomic and molecular states.
Time-resolved emission measurements are combined with analytical models describing the population dynamics of excited states.
The analysis considers electron-impact excitation, population cascades, and non-radiative collisional de-excitation processes.
Another important research objective is the determination of spatially and temporally resolved electron energy distribution functions (EEDF).
The investigations examine directed electron motion, secondary electrons, and ionization processes occurring within the plasma discharge.
The findings demonstrate the significant contribution of energetic electrons to excitation and ionization dynamics.
Additionally, the influence of cascade processes on gas-temperature determination from rotational populations of excited hydrogen molecules is evaluated.
The dissertation also identifies excitation processes caused by energetic hydrogen atoms generated through ion bombardment at electrode surfaces.
The developed diagnostic methods extend the possibilities of plasma characterization and contribute to a better understanding of electron kinetics and plasma chemistry in radio-frequency discharges.