M. Tadokoro et al., TIME-RESOLVED OPTICAL-EMISSION SPECTROSCOPY OF AN INDUCTIVELY-COUPLEDPLASMA IN ARGON AND OXYGEN, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 57(1), 1998, pp. 43-46
We present the space-time resolved excitation data for a single coil i
nductively coupled plasma (ICP) reactor operating in collision dominat
ed regime in argon and oxygen at 13.56 MHz. Robot assisted scanning wa
s used in order to obtain Abel inverted radial profiles of emission an
d subsequently of the net excitation rate as well as the number densit
y of excited states. The net excitation rate in argon has modulation c
lose to the walls due to the azimuthal field time dependence and a lar
ge bulk value independent of the time presumably due to low energy ele
ctron-metastable atom collisions. The time resolved profile in oxygen
shows a much more pronounced modulation due to the azimuthal field and
a much lower degree of excitation for the center of the tube. At low
pressures a structure is observed in the temporal dependence of the ne
t excitation rate that is consistent with two different mechanisms of
electron acceleration with phase shift of pi/4: (I) by azimuthal field
and (II) due to the drift motion in crossed electric and magnetic fie
lds that leads to a motion in the azimuthal or radial direction and co
nsequently to energy gain.