8 research outputs found
Modeling characterisation of a bipolar pulsed discharge
We apply particle based kinetic simulations to explore the characteristics of
a low-pressure gas discharge driven by high-voltage ( kV) pulses with
alternating polarity, with a duty cycle of 1% and a repetition rate
of 5 kHz. The computations allow tracing the spatio-temporal development of
several discharge characteristics, the potential and electric field
distributions, charged particle densities and fluxes, the mean ion energy at
the electrode surfaces, etc. As such discharges have important surface
processing applications, e.g. in the treatment of artificial bones, we analyse
the time-dependence of the flux and the mean energy of the ions reaching the
electrode surfaces, which can be both conducting and dielectric. Our
investigations are conducted for argon buffer gas in the 40-140 Pa pressure
range, for 1-5 cm electrode gaps and voltage pulse amplitudes ranging between
600 V and 1200 V
Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids
The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode
On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H-2 microwave plasma torch
A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream
On the interplay of gas dynamics and the electromagnetic field in an atmospheric Ar/H-2 microwave plasma torch
A complementary simulation and experimental study of an atmospheric pressure microwave torch operating in pure argon or argon/hydrogen mixtures is presented. The modelling part describes a numerical model coupling the gas dynamics and mixing to the electromagnetic field simulations. Since the numerical model is not fully self-consistent and requires the electron density as an input, quite extensive spatially resolved Stark broadening measurements were performed for various gas compositions and input powers. In addition, the experimental part includes Rayleigh scattering measurements, which are used for the validation of the model. The paper comments on the changes in the gas temperature and hydrogen dissociation with the gas composition and input power, showing in particular that the dependence on the gas composition is relatively strong and non-monotonic. In addition, the work provides interesting insight into the plasma sustainment mechanism by showing that the power absorption profile in the plasma has two distinct maxima: one at the nozzle tip and one further upstream
Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids
Abstract The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode.</p