Atmospheric pressure plasma sources have been
emerging as a new tool for modifying polymer w1–3x
andyor metal surfaces w4–7x. Especially, radio frequency
(RF) ejected plasma sources operating in air can be
used for arbitrary shaped objects, regardless of its
conductivity, i.e. for both insulating and conducting
objects. For the success of the source, efficient generation of radicals such as atomic oxygen is very important,
while keeping relevant gas temperatures in the plasma
source for specific applications w1,8,9x. Also, discharges
need to be maintained as glow-like characteristics without streamers for uniform and high-quality surface treatments. Gas economy is another issue to be resolved in
the atmospheric plasma source design, since large
amount of expensive helium gas is required for quiescent
glow-like discharges at atmospheric pressure. However,
theoretical understanding of the discharge mechanism is
not established yet, and diagnostic tools are very limited
in atmospheric pressure discharge.