83 research outputs found
Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air
Space and time resolved concentrations of helium metastable atoms in an
atmospheric pressure radio-frequency micro-plasma jet were measured using
tunable diode laser absorption spectroscopy. Spatial profiles as well as
lifetime measurements show significant influences of air entering the discharge
from the front nozzle and of impurities originating from the gas supply system.
Quenching of metastables was used to deduce quantitative concentrations of
intruding impurities. The impurity profile along the jet axis was determined
from optical emission spectroscopy as well as their dependance on the feed gas
flow through the jet.Comment: Journal of Physics D: Applied Physics (accepted), 6 page
Argon metastable dynamics in a filamentary jet micro-discharge at atmospheric pressure
Space and time resolved concentrations of Ar () metastable atoms at
the exit of an atmospheric pressure radio-frequency micro-plasma jet were
measured using tunable diode laser absorption spectroscopy. The discharge
features a coaxial geometry with a hollow capillary as an inner electrode and a
ceramic tube with metal ring as outer electrode. Absorption profiles of
metastable atoms as well as optical emission measurements reveal the dynamics
and the filamentary structure of the discharge. The average spatial
distribution of Ar metastables is characterized with and without a target in
front of the jet, showing that the target potential and therewith the electric
field distribution substantially changes the filaments' expansion. Together
with the detailed analysis of the ignition phase and the discharge's behavior
under pulsed operation, the results give an insight into the excitation and
de-excitation mechanisms
Radio-frequency discharges in Oxygen. Part 1: Modeling
In this series of three papers we present results from a combined
experimental and theoretical effort to quantitatively describe capacitively
coupled radio-frequency discharges in oxygen. The particle-in-cell Monte-Carlo
model on which the theoretical description is based will be described in the
present paper. It treats space charge fields and transport processes on an
equal footing with the most important plasma-chemical reactions. For given
external voltage and pressure, the model determines the electric potential
within the discharge and the distribution functions for electrons, negatively
charged atomic oxygen, and positively charged molecular oxygen. Previously used
scattering and reaction cross section data are critically assessed and in some
cases modified. To validate our model, we compare the densities in the bulk of
the discharge with experimental data and find good agreement, indicating that
essential aspects of an oxygen discharge are captured.Comment: 11 pages, 10 figure
Particle-in-cell Monte Carlo and fluid simulations of argon-oxygen plasma: Comparisons with experiments and validations
This article was published in the journal, Physics of plasmas and is also available at: http://pop.aip.org/pop/top.jsp or http://dx.doi.org/10.1063/1.2179430Particle-in-cell Monte Carlo collision (PIC-MCC) and fluid simulations of argon-oxygen plasmas in
capacitively and inductively coupled plasma reactors are presented. Potential profiles and electron/
ion kinetic information such as electron/ion energy distributions and temperatures are compared
with experimental data as well as with other analytical and numerical results. One-dimensional
PIC-MCC simulations compare favorably with experimental data obtained in capacitively coupled
reactors over a wide range of pressure and power. Two-dimensional fluid simulations of capacitive
discharges differs from the results of PIC-MCC simulations as nonlocal effects play an important
role in these discharges. Fluid simulations as nonlocal inductively coupled plasmas, however, agree
favorably with experimental observations
The influence of glucocorticosteroid application on the activity of ?-amylase in the serum
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