A5008878979- Plasma Applications and Diagnostics
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- High-Temperature Coating Behaviors
- Advanced materials and composites
- Laser Design and Applications
- Metal Alloys Wear and Properties
- Metal and Thin Film Mechanics
- Dust and Plasma Wave Phenomena
- Catalytic Processes in Materials Science
- Gas Sensing Nanomaterials and Sensors
- Electrohydrodynamics and Fluid Dynamics
- Spectroscopy and Laser Applications
- Plasma and Flow Control in Aerodynamics
- Gas Dynamics and Kinetic Theory
- Magnetic confinement fusion research
- Mass Spectrometry Techniques and Applications
- Atomic and Molecular Physics
- Diamond and Carbon-based Materials Research
- Tribology and Wear Analysis
- Advanced ceramic materials synthesis
- Particle accelerators and beam dynamics
- Vacuum and Plasma Arcs
- Material Properties and Applications
- Combustion and Detonation Processes
University of York
2012-2023
Tampere University
1994-2014
Queen's University Belfast
2008-2012
Keskuslaboratorio
2009
Ruhr University Bochum
2006-2008
University of Jyväskylä
2005
Metso (Finland)
2003-2004
University of Duisburg-Essen
2001-2002
Outokumpu (Finland)
1988-1989
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...
The two-photon resonances of atomic hydrogen (λ = 2×205.1 nm), nitrogen 2×206.6 nm) and oxygen 2×225.6 are investigated together with two selected transitions in krypton 2×204.2 xenon 2×225.5 nm). natural lifetimes the excited states, quenching coefficients for most important collisions partners, relevant ratios excitation cross sections measured. These data can be applied to provide a calibration laser-induced fluorescence measurements based on comparisons spectrally neighbouring noble gas...
The atmospheric pressure plasma jet is a capacitively coupled radio frequency discharge (13.56 MHz) running with high helium flux (2 m3 h−1) between concentric electrodes. Small amounts (0.5%) of admixed molecular oxygen do not disturb the homogeneous discharge. effluent leaving through ring-shaped nozzle contains concentrations radicals at low gas temperature—the key property for variety applications aiming treatment thermally sensitive surfaces. We report on absolute atomic density...
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...
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 coplanar microscale atmospheric pressure plasma jet (μ-APPJ) is a capacitively coupled radio frequency discharge (13.56 MHz, ∼15 W rf power) designed for optimized optical diagnostic access. It operated in homogeneous glow mode with noble gas flow (1.4 slm He) containing small admixture of molecular oxygen (∼0.5%). Ground state atomic densities the effluent up to 2 × 1014 cm−3 are measured by two-photon absorption laser-induced fluorescence spectroscopy (TALIF) providing space resolved...
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 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...
The potential of laser-induced fluorescence spectroscopy atoms is reviewed with emphasis on the determination absolute densities. Examples experiments single-photon and two-photon excitation are presented. Calibration methods applicable different schemes discussed. A new method presented that has to allow measurement in plasmas elevated pressure where collisional depletion excited state present.
The planar 13.56 MHz RF-excited low temperature atmospheric pressure plasma jet (APPJ) investigated in this study is operated with helium feed gas and a small molecular oxygen admixture. effluent leaving the discharge through jet's nozzle contains very few charged particles high reactive species' density. As its main radical, essential for numerous applications, ground state atomic density APPJ's measured spatially resolved two-photon absorption laser induced fluorescence spectroscopy. at...
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 micro atmospheric pressure plasma jet is an rf driven (13.56 MHz, ∼20 W) capacitively coupled discharge producing a homogeneous at ambient when fed with gas flow of helium (1.4 slm) containing small admixtures oxygen (∼0.5%). design provides excellent optical access to the core. Ground state atomic densities up 3×1016 cm−3 are measured spatially resolved in core by absolutely calibrated two-photon absorption laser-induced fluorescence spectroscopy. density builds over first 8 mm channel...
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...
Thermally-sprayed alumina based materials, e.g., alumina-titania (Al2O3-TiO2), are commonly applied as wear resistant coatings in industrial applications. Properties of the depend on spray process, powder morphology, and chemical composition powder. In this study, from Al2O3 Al2O3-13TiO2 powders were sprayed with plasma high-velocity oxygen-fuel (HVOF) processes. Both, fused crushed, agglomerated sintered studied compared to pure Al2O3. The tested for abrasion, erosion, cavitation...
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...
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...
Diagnostic based modelling (DBM) actively combines complementary advantages of numerical plasma simulations and relatively simple optical emission spectroscopy (OES). DBM is employed to determine absolute atomic oxygen ground state densities in a helium?oxygen radio-frequency driven atmospheric pressure jet. A comparatively one-dimensional simulation yields detailed information on electron properties governing the population dynamics excited states. Important characteristics are found be...
Absolute atomic oxygen ground state densities in a radio-frequency driven atmospheric pressure plasma jet, operated helium-oxygen mixture, are determined using diagnostic based modeling. One-dimensional numerical simulations of the electron dynamics combined with time integrated optical emission spectroscopy. The population upper O 3p P3 (λ=844 nm) is governed by direct impact excitation, dissociative radiation losses, and collisional induced quenching. values for obtained through comparison...