A5015062886- Plasma Diagnostics and Applications
- Plasma Applications and Diagnostics
- Laser-induced spectroscopy and plasma
- Electrohydrodynamics and Fluid Dynamics
- Dust and Plasma Wave Phenomena
- Diamond and Carbon-based Materials Research
- Metal and Thin Film Mechanics
- Gas Sensing Nanomaterials and Sensors
- Atomic and Molecular Physics
- Magnetic confinement fusion research
- Laser Design and Applications
- Catalytic Processes in Materials Science
- Particle accelerators and beam dynamics
- Mass Spectrometry Techniques and Applications
- Electrostatic Discharge in Electronics
- Ionosphere and magnetosphere dynamics
- Analytical Chemistry and Sensors
- Ion-surface interactions and analysis
- Gas Dynamics and Kinetic Theory
- High voltage insulation and dielectric phenomena
- Plasma and Flow Control in Aerodynamics
- Semiconductor materials and devices
- Surface Modification and Superhydrophobicity
- Vacuum and Plasma Arcs
- Spectroscopy and Laser Applications
Dublin City University
2021-2024
Culham Science Centre
2024
Culham Centre for Fusion Energy
2024
University of York
2012-2021
Physique des interactions ioniques et moléculaires
2021
Queen's University Belfast
2007-2012
Keio University
2009
Ruhr University Bochum
2004-2008
Plasma Technology (United States)
2005
Essen University Hospital
2002
In most applications helium-based plasma jets operate in an open-air environment. The presence of humid air the jet will influence chemistry and can lead to production a broader range reactive species. We explore on species radio frequency (rf)-driven atmospheric-pressure helium–oxygen mixture plasmas (He–O2, helium with 5000 ppm admixture oxygen) for wide impurity levels 0–500 relative humidities from 0% 100% using zero-dimensional, time-dependent global model. Comparisons are made...
Atomic oxygen formation in a radio-frequency driven micro-atmospheric pressure plasma jet is investigated using both advanced optical diagnostics and numerical simulations of the dynamic chemistry. Laser spectroscopic measurements absolute densities ground state atomic reveal steep gradients at interface between core effluent region. Spatial profiles resolving interelectrode gap within indicate that volume processes dominate over surface reactions. Details production destruction are...
An industrial, confined, dual frequency, capacitively coupled, radio-frequency plasma etch reactor (Exelan®, Lam Research) has been modified for spatially resolved optical measurements. Space and phase emission spectroscopy yields insight into the dynamics of discharge. A strong coupling two frequencies is observed in profiles. Consequently, ionization dynamics, probed through excitation, determined by both frequencies. The control density high frequency is, therefore, also influenced low...
Biomedical applications of non-equilibrium atmospheric pressure plasmas have attracted intense interest in the past few years. Many plasma sources diverse design been proposed for these applications, but relationship between source characteristics and application performance is not well-understood, indeed many are poorly characterized. This circumstance an impediment to progress development. A reference with well-understood highly reproducible may be important tool this context. Researchers...
Absolute densities of singlet delta oxygen (SDO) molecules were measured using infrared optical emission spectroscopy in the flowing effluents two different atmospheric-pressure plasma jets (APPJs): a capacitively coupled radio-frequency-driven jet (rf-APPJ) and lower frequency kilohertz-driven dielectric barrier discharge jet. The operated helium, with small admixtures molecular (O2 < 2%). High absolute SDO up to 6.2 × 1015 cm−3 at approximately 10 cm downstream. rf-APPJ seems be...
We unravel the complex chemistry in both neutral and ionic systems of a radio-frequency-driven atmospheric-pressure plasma helium–oxygen mixture (He–0.5% O2) with air impurity levels from 0 to 500 ppm relative humidity 0% 100% using zero-dimensional, time-dependent global model. Effects humid on absolute densities dominant production destruction pathways biologically relevant reactive species are clarified. A few hundred crucially changes simple oxygen-dependent oxygen–nitrogen–hydrogen...
The effect of a cold (<40 °C) radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. Gel electrophoresis was used to analyze the forms post-treatment. experimental data are fitted rate equation model that allows for quantitative determination rates single and double strand break formation. formation breaks correlates well with atomic oxygen density. Taken other measurements, this indicates neutral components in effective inducing breaks.
Absolute densities of metastable He(23S1) atoms were measured line-of-sight integrated along the discharge channel a capacitively coupled radio-frequency driven atmospheric pressure plasma jet operated in technologically relevant helium–oxygen mixtures by tunable diode-laser absorption spectroscopy. The dependences density homogeneous-glow-like α-mode with oxygen admixtures up to 1% investigated. results are compared one-dimensional numerical simulation, which includes semi-kinetical...
The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric induce spatial asymmetries offer control of the spatiotemporal electron heating associated structures. Sawtooth with different rise fall rates are employed truncated Fourier series approximations an ideal...
The formation of reactive species in the afterglow a radio-frequency-driven atmospheric-pressure plasma fixed helium–oxygen feed gas mixture (He+0.5%O2) with humid air impurity (a few hundred ppm) is investigated by means an extensive global chemical kinetics model. As original objective, we explore effects on biologically relevant oxygen-dependent system. After milliseconds environment, densities atomic oxygen (O) decreases from 1015 to 1013 cm−3 and singlet delta molecular (O2(1D)) order...
This paper brings the comparison of performances CO2 conversion by plasma and plasma-assisted catalysis based on data collected from literature in this field, organised an open access online database. tool is to all users carry out their own analyses, but also contributors who wish add database order improve relevance comparisons made, ultimately efficiency plasma-catalysis. The creation user interface motivated fact that plasma-catalysis a fast-growing field for processes, be it...
Despite enormous potential for technological applications, fundamentals of stable non-equilibrium micro-plasmas at ambient pressure are still only partly understood. Micro-plasma jets one sub-group these plasma sources. For an understanding it is particularly important to analyse transport phenomena energy and particles within between the core effluent discharge. The complexity problem requires combination correlation various highly sophisticated diagnostics yielding different information...
The dynamics of high energetic electrons ( 11.7 eV) in a modified industrial confined dual-frequency capacitively coupled RF discharge (Exelan, Lam Research Inc.), operated at 1.937 MHz and 27.118 MHz, is investigated by means phase resolved optical emission spectroscopy.Operating He-O 2 plasma with small rare gas admixtures the measured, one-dimensional spatial resolution along axis.Both low frequency cycle are resolved.The diagnostic based on time dependent measurements population...
Atmospheric pressure plasmas are sources of biologically active oxygen and nitrogen species, which makes them potentially suitable for the use as biomedical devices. Here, experiments simulations combined to investigate formation key reactive atomic (O) hydroxyl radicals (OH), in a radio-frequency driven atmospheric plasma jet operated humidified helium. Vacuum ultra-violet high-resolution Fourier-transform absorption spectroscopy broad-band used measure absolute densities O OH. These...
The power absorption dynamics of electrons and the electrical asymmetry effect in capacitive radio-frequency plasmas operated CF4 driven by tailored voltage waveforms are investigated experimentally combination with kinetic simulations. driving generated as a superposition multiple consecutive harmonics fundamental frequency 13.56 MHz. Peaks/valleys sawtooth used to study effects amplitude slope asymmetries waveform on electron generation DC self-bias an electronegative plasma at different...
Abstract Spatially resolved tunable diode-laser absorption measurements of the absolute densities He-I (2 3 S 1 ) metastables in a micro atmospheric pressure plasma jet operated He/N 2 and driven by ‘peaks’- ‘valleys’-type tailored voltage waveforms are presented. The performed at different nitrogen admixture concentrations peak-to-peak voltages with that consist up to four consecutive harmonics fundamental frequency 13.56 MHz. Comparisons measured metastable those obtained from...
Abstract The field of low-temperature plasmas (LTPs) excels by virtue its broad intellectual diversity, interdisciplinarity and range applications. This great diversity also challenges researchers in communicating the outcomes their investigations, as common practices expectations for reporting vary widely many disciplines that either fall under LTP umbrella or interact closely with topics. These encompass comparing measurements made different laboratories, exchanging sharing computer...
Abstract Micro plasmas operated at ambient pressure with dimensions of the confining geometry in order a few ten micrometers to millimeter are actually focus interest due broad regime applicability they offer and similarly range open physical questions. Here we present optical measurements within discharge core effluent region an especially developed micro jet. To get understanding complex system this it is important analyse transport phenomena energy particles both parts by various highly...
The first direct measurements of atomic nitrogen species in a radio-frequency atmospheric-pressure plasma jet (APPJ) are presented. Atomic radicals play key role new medicine applications APPJs. were performed with two-photon absorption laser-induced fluorescence diagnostic, using 206.65 nm laser photons for the excitation ground-state N atoms and observing light around 744 nm. APPJ was run helium gas flow 1 slm varying small admixtures molecular 0–0.7 vol%. A maximum measured concentration...
The complex dynamics of ionization and excitation mechanisms in capacitively coupled radio-frequency plasmas is discussed for single- dual-frequency operations low-pressure atmospheric pressure plasmas. Electrons are energized through the electric fields vicinity plasma boundary sheaths. Distinctly different power dissipation can either co-exist or initiate mode transitions exhibiting characteristic spatio-temporal structures. Phase resolved optical emission spectroscopy, combination with...
Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, particular, medicine. Absolute densities of oxygen and nitrogen were measured radio-frequency driven non-equilibrium operated at using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline unique VUV Fourier-transform spectrometer. Measurements carried out plasmas helium with air-like N2/O2 (4:1) admixtures. A maximum O-atom...
Low-pressure capacitively coupled radio frequency discharges operated in O2 and driven by tailored voltage waveforms are investigated experimentally means of kinetic simulations. Pulse-type (peaks/valleys) sawtooth-type that consist up to four consecutive harmonics the fundamental used study amplitude asymmetry effect as well slope at different frequencies (5, 10, 15 MHz) pressures (50–700 mTorr). Values DC self-bias determined spatio-temporal excitation rates derived from phase resolved...
Abstract Atmospheric pressure capacitively coupled radio frequency discharges operated in He/N 2 mixtures and driven by tailored voltage waveforms are investigated experimentally using a COST microplasma reference jet means of kinetic simulations as function the reactive gas admixture number consecutive harmonics used to drive plasma. Pulse-type ‘peaks’-waveforms, that consist up four fundamental ( f = 13.56 MHz), at fixed peak-to-peak 400 V. Based on an excellent agreement between...
Neutral gas depletion mechanisms are investigated in a dense low-temperature argon plasma—an inductively coupled magnetic neutral loop (NL) discharge. Gas temperatures deduced from the Doppler profile of 772.38 nm line absorbed by metastable atoms. Electron density and temperature measurements reveal that at pressures below 0.1 Pa, relatively high degrees ionization (exceeding 1%) result electron pressures, pe = kTene, exceeding pressure. In this regime, dynamics has to be taken into account...