Radio frequency (rf) atmospheric pressure glow discharges (APGDs) have
received growing attention for their exciting scope of new science and their
immense potential for widespread applications. While geometrically similar to
conventional low-pressure discharges used in the semiconductor industry for
decades, rf APGDs present new physics that require investigation.
This thesis presents an experimental and computational study of helium rfAPGDs
aimed at making a contribution to the current understanding of these
discharges and enabling their optimization for different applications. The timely
interest and significance of this work is highlighted by the publication of different
parts of this thesis in 10 peer-reviewed international journals.
Starting with the electron trapping in rf APGDs, the thesis looks into the
electron heating mechanism responsible for sustaining the discharges, the
influence of the rf excitation frequency on the discharge characteristics, the role
of impurities in the discharge chemistry as well as the evolution of the discharge
as the size is reduced down to microplasma dimensions. The findings of this
research are based on the synergistic use of electrical measurements, optical
diagnostics and self-developed computational models.
With the knowledge gained from this thesis, rf-APGDs can be readily used
for a wide-range of applications including biological decontaminations, nanostructure
fabrication and portable gas analyzers.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.