ORCID Profile
0000-0002-1793-3873
Current Organisation
Australian National University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Plasma Physics; Fusion Plasmas; Electrical Discharges | Atomic, Molecular, Nuclear, Particle and Plasma Physics | Condensed Matter Physics | Colloid and Surface Chemistry | Polymerisation Mechanisms | Physical Chemistry (Incl. Structural) | Higher Education | Materials Engineering not elsewhere classified | Surfaces and Structural Properties of Condensed Matter
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Nuclear Energy | Renewable Energy not elsewhere classified | Energy Storage (excl. Hydrogen) | School/Institution not elsewhere classified | Climate and Climate Change not elsewhere classified | Expanding Knowledge in the Chemical Sciences |
Related Links
Publications
Deuterium retention and near-surface modification of ion-irradiated diamond exposed to fusion-relevant plasma
Publisher: IOP Publishing
Date: 04-2014
Low-pressure hydrogen plasmas explored using a global model
Publisher: IOP Publishing
Date: 17-12-2015
Periodic formation and propagation of double layers in the expanding chamber of an inductive discharge operating in Ar∕SF6 mixtures
Publisher: AIP Publishing
Date: 15-07-2005
DOI: 10.1063/1.1947387
Abstract: It has previously been shown [Tuszewski et al., Plasma Sources Sci. Technol. 12, 396 (2003)] that inductive discharges in electronegative gases are subject to two types of instability: the source instability related to the E to H transition and a transport instability, occurring downstream when an expanding chamber is present. These two types of instability are observed in our “helicon” reactor operated without a static magnetic field in low-pressure Ar∕SF6 mixtures. Temporally and spatially resolved measurements show that, in our experiment, the downstream instability is a periodic formation and propagation of a double layer. The double layer is born at the end of the source tube and propagates slowly to the end of the expansion region with a velocity of 150ms−1.
A novel technique for plasma density measurement using surface-wave transmission spectra
Publisher: IOP Publishing
Date: 11-2005
Helium plasma induced nanostructure formation in copper and nickel
Publisher: IOP Publishing
Date: 28-01-2018
Spatial evolution of an ion beam created by a geometrically expanding low-pressure argon plasma
Publisher: AIP Publishing
Date: 02-06-2008
DOI: 10.1063/1.2938720
Abstract: The spatial distribution of an ion beam—created at the interface of a small diameter plasma source and much larger diameter diffusion chamber—is studied in a low-pressure inductively coupled plasma using a retarding field energy analyzer. It is found that the ion beam density decays axially and radially in the diffusion chamber following the expansion of the plasma from the source region. The radial distribution of the ion beam indicates that the acceleration region has a convex shape and is located just outside the source exit, giving rise to a hemispherical plasma expansion into the diffusion chamber.
Effect of rhenium irradiations on the mechanical properties of tungsten for nuclear fusion applications
Publisher: Elsevier BV
Date: 08-2016
Metastable CF and CF2molecules in CF4inductively-coupled plasmas
Publisher: IOP Publishing
Date: 31-01-2006
Measuring temperature effects on nano-bubble growth in tungsten with grazing incidence small angle X-ray scattering
Publisher: Elsevier BV
Date: 08-2017
Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma
Publisher: IOP Publishing
Date: 22-06-2015
Coherence imaging for ion temperature and flow measurements in a low-temperature helicon plasma source
Publisher: IOP Publishing
Date: 25-01-2016
Spatiotemporal Pattern Formation in an Atmospheric Plasma Discharge
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2008
NEXAFS spectroscopy of CVD diamond films exposed to fusion relevant hydrogen plasma
Publisher: Elsevier BV
Date: 04-2013
Spatially limited ion acoustic wave activity in low-pressure helicon discharges
Publisher: AIP Publishing
Date: 08-09-2004
DOI: 10.1063/1.1785790
Abstract: Ion acoustic wave phenomena are studied and compared in two low-pressure argon discharges created by helicon sources. The wave litudes are spatially localized near the edge of a plasma column as the litudes of the “mirror waves” that are separated from the helicon source frequency by the ion wave frequency. Dependencies of the ion wave on radial position, pressure, input power, and magnetic field are investigated. Measurements of the wavelength show that the wave is traveling azimuthally at approximately the ion sound speed in the direction of electron gyration. Although the wave spectra are indicative of a parametric decay phenomenon, it seems more likely that the radial plasma pressure gradient drives an ion acoustic instability which then modulates the helicon source.
Effect of W self-implantation and He plasma exposure on early-stage defect and bubble formation in tungsten
Publisher: IOP Publishing
Date: 18-04-2018
Characterization of a radio-frequency inductively coupled electrothermal plasma thruster
Publisher: AIP Publishing
Date: 27-07-2021
DOI: 10.1063/5.0056124
Abstract: A radio-frequency (RF) inductively coupled electrothermal plasma thruster operating with argon is experimentally characterized for different mass flow rates, RF powers, and propellant injection configurations. Depending on the propellant mass flow rate, significant neutral gas heating is observed with effective stagnation temperatures around 2000 K (giving a maximum estimated thrust and specific impulse of about 100 mN and 125 s, respectively) for absorbed powers between 300 and 500 W. A self-consistent theoretical discharge model is developed and used to study the basic physics and operation of RF electrothermal thrusters, and predictions of the gas temperature are in good agreement with experimental measurements. The model identifies primary power inefficiencies as electron-neutral excitation losses and neutral gas heat losses to the thruster walls. Both experimental and theoretical results indicate that a relatively high stagnation pressure (of the order of 100 Torr or higher) is critical for high performance. For pressures significantly below this the electron-neutral collisional power transfer is too low to effectively heat the neutral gas.
High-beta plasma effects in a low-pressure helicon plasma
Publisher: AIP Publishing
Date: 12-2007
DOI: 10.1063/1.2802080
Abstract: In this work, high-beta plasma effects are investigated in a low-pressure helicon plasma source attached to a large volume diffusion chamber. When operating above an input power of 900W and a magnetic field of 30G a narrow column of bright blue light (due to Ar II radiation) is observed along the axis of the diffusion chamber. With this blue mode, the plasma density is axially very uniform in the diffusion chamber however, the radial profiles are not, suggesting that a large diamagnetic current might be induced. The diamagnetic behavior of the plasma has been investigated by measuring the temporal evolution of the magnetic field (Bz) and the plasma kinetic pressure when operating in a pulsed discharge mode. It is found that although the electron pressure can exceed the magnetic field pressure by a factor of 2, a complete expulsion of the magnetic field from the plasma interior is not observed. In fact, under our operating conditions with magnetized ions, the maximum diamagnetism observed is ∼2%. It is observed that the magnetic field displays the strongest change at the plasma centre, which corresponds to the maximum in the plasma kinetic pressure. These results suggest that the magnetic field diffuses into the plasma sufficiently quickly that on a long time scale only a slight perturbation of the magnetic field is ever observed.
Double layer formation in the expanding region of an inductively coupled electronegative plasma
Publisher: AIP Publishing
Date: 24-02-2005
DOI: 10.1063/1.1869533
Abstract: Double-layers (DLs) were observed in the expanding region of an inductively coupled plasma with Ar–SF6 gas mixtures. No DL was observed in pure argon or SF6 fractions below a few percent. They exist over a wide range of power and pressure although they are only stable for a small window of electronegativity (typically between 8% and 13% of SF6 at 1 mTorr), becoming unstable at higher electronegativity. They seem to be formed at the boundary between the source tube and the diffusion chamber and act as an internal boundary [the litude being roughly 1.5(kTe∕e)] between a high electron density, high electron temperature, low electronegativity plasma upstream (in the source), and a low electron density, low electron temperature, high electronegativity plasma downstream.
Erratum: “Spatial evolution of an ion beam created by a geometrically expanding low-pressure argon plasma” [Appl. Phys. Lett. 92, 221508 (2008)]
Publisher: AIP Publishing
Date: 14-07-2008
DOI: 10.1063/1.2960321
Superior performance of plasma treated water as an anodizing electrolyte for producing nanoporous titanium dioxide nanotubes
Publisher: Wiley
Date: 17-07-2017
Depletion of atomic hydrogen in a high power helicon discharge
Publisher: IOP Publishing
Date: 11-2020
Abstract: Depletion of the ground state atomic hydrogen density has been directly measured using two-photon laser-induced fluorescence in a high-density helicon plasma. The depletion is correlated with the plasma pressure becoming increasingly higher than the neutral gas fill pressure. Spatially resolved measurements show depletion of atomic hydrogen in the centre of the discharge chamber. Temporally resolved measurements display a replenishment of atomic hydrogen in the plasma afterglow at high plasma densities in comparison to the typical two-step decay at lower plasma densities.
Temperature dependence of retarded recrystallisation in helium plasma-exposed tungsten
Publisher: IOP Publishing
Date: 30-07-2019
Superfast Proton Diffusion Achieved in a Plasma-Polymerized Fuel-Cell Membrane
Publisher: American Chemical Society (ACS)
Date: 27-02-2013
DOI: 10.1021/JP309259K
Mechanical properties of tungsten following rhenium ion and helium plasma exposure
Publisher: Elsevier BV
Date: 08-2017
Optimization of a Cl2–H2 inductively coupled plasma etching process adapted to nonthermalized InP wafers for the realization of deep ridge heterostructures
Publisher: American Vacuum Society
Date: 09-2006
DOI: 10.1116/1.2348728
Abstract: Inductively coupled plasma etching using Cl2–H2 chemistry with no additive gas (CH4, Ar, or N2) is studied to realize deep (& μm) ridges with smooth and vertical sidewalls. The process is optimized for nonthermalized InP wafers to avoid the use of thermal grease. Cleaning of the rear side of the wafer after etching is avoided, which is suitable for an industrial process or for critical subsequent steps such as epitaxial regrowth. The influence of the Cl2∕H2 ratio on the etching mechanism is investigated for both InP bulk layers and InGaAs∕InP or InGaAlAs∕InP heterostructures. The authors show that this ratio is the main parameter controlling the ridge profile, in a similar way for both bulk InP and InGa(Al)As∕InP s les. Smooth and vertical sidewalls with neither undercuts nor notches can be obtained in the 0.5–1mT pressure range for a hydrogen percentage of 35%–45% in the gas mixture. Etching rates from 900to1300nm∕min together with a selectivity over SiNx dielectric mask as high as 24:1–29:1 are measured for the InP bulk layers under these conditions. Etching does not affect the optical quality of the heterostructures as evidenced from micro-photoluminescence measurements performed on 1.6-to0.85-μm-wide deep etched ridge waveguides. The process is well adapted to the realization of low loss deep ridge waveguides or buried heterostructures.
Ion flux dependence of atomic hydrogen loss probabilities on tungsten and carbon surfaces
Publisher: Elsevier BV
Date: 08-2014
Design and characterization of the Magnetized Plasma Interaction Experiment (MAGPIE): A new source for plasma-material interaction studies
Publisher: IOP Publishing
Date: 10-2012
High density negative hydrogen ion production in a high power pulsed helicon discharge
Publisher: IOP Publishing
Date: 25-10-2018
Wave modeling in a cylindrical non-uniform helicon discharge
Publisher: AIP Publishing
Date: 08-2012
DOI: 10.1063/1.4748874
Abstract: A radio frequency field solver based on Maxwell's equations and a cold plasma dielectric tensor is employed to describe wave phenomena observed in a cylindrical non-uniform helicon discharge. The experiment is carried out on a recently built linear plasma-material interaction machine: The magnetized plasma interaction experiment [Blackwell et al., Plasma Sources Sci. Technol. (submitted)], in which both plasma density and static magnetic field are functions of axial position. The field strength increases by a factor of 15 from source to target plate, and the plasma density and electron temperature are radially non-uniform. With an enhancement factor of 9.5 to the electron-ion Coulomb collision frequency, a 12% reduction in the antenna radius, and the same other conditions as employed in the experiment, the solver produces axial and radial profiles of wave litude and phase that are consistent with measurements. A numerical study on the effects of axial gradient in plasma density and static magnetic field on wave propagations is performed, revealing that the helicon wave has weaker attenuation away from the antenna in a focused field compared to a uniform field. This may be consistent with observations of increased ionization efficiency and plasma production in a non-uniform field. We find that the relationship between plasma density, static magnetic field strength, and axial wavelength agrees well with a simple theory developed previously. A numerical scan of the enhancement factor to the electron-ion Coulomb collision frequency from 1 to 15 shows that the wave litude is lowered and the power deposited into the core plasma decreases as the enhancement factor increases, possibly due to the stronger edge heating for higher collision frequencies.
Equilibrium model for two low-pressure electronegative plasmas connected by a double layer
Publisher: AIP Publishing
Date: 09-2006
DOI: 10.1063/1.2345353
Abstract: Plihon et al. [J. Appl. Phys. 98, 023306 (2005)] have recently shown that double layers usually form during the expansion of a low pressure electronegative plasma. These double layers act as permeable internal boundaries between the source (upstream) plasma and the downstream expanding plasma positive ions flow from upstream to downstream whereas negative ions flow in the opposite direction. So far, the detailed physical mechanisms leading to their formation have not been identified. In this paper, we develop a model for the two plasma equilibria, upstream and downstream, assuming that the double layer exists and couples the two plasmas. At very low pressure, typically 0.5mTorr, the coupling is strong and acts both ways. The negative ions created downstream contributes to the upstream equilibrium as well as the upstream positive ions contribute to the downstream equilibrium. As the pressure increases, the situation becomes asymmetric. The source plasma is not affected by the negative ions flowing from downstream, whereas the positive ions coming from the source control the downstream plasma equilibrium, where local ionization is negligible.
Experimental investigation of double layers in expanding plasmas
Publisher: AIP Publishing
Date: 2007
DOI: 10.1063/1.2424429
Abstract: Double layers (DLs) have been observed in a plasma reactor composed of a source chamber attached to a larger expanding chamber. Positive ion beams generated across the DL were characterized in the low plasma potential region using retarding field energy analyzers. In electropositive gases, DLs were formed at very low pressures (between 0.1 and 1mTorr) with the plasma expansion forced by a strongly erging magnetic field. The DL remains static, robust to changes in boundary conditions, and its position is related to the magnetic field lines. The voltage drop across the DL increases with decreasing pressure i.e., with increasing electron temperature (around 20V at 0.17mTorr). DLs were also observed in electronegative gases without a magnetic field over a greater range of pressure (0.5 to 10mTorr). The actual profile of the electronegative DL is very sensitive to external parameters and intrusive elements, and they propagate at high negative ion fraction. Electrostatic probes measurements and laser-induced photodetachment show discontinuities in all plasma parameters (electron density, electron temperature, negative ion fraction) at the DL position. The voltage drop across the electronegative DL is about 8V, is independent of the gas pressure and therefore of the electron temperature.
Nonlinear instability dynamics in a high-density, high-beta plasma
Publisher: AIP Publishing
Date: 02-2009
DOI: 10.1063/1.3074790
Transport simulations of linear plasma generators with the B2.5-Eirene and EMC3-Eirene codes
Publisher: Elsevier BV
Date: 08-2015
Gas phase optical emission spectroscopy during remote plasma chemical vapour deposition of GaN and relation to the growth dynamics
Publisher: IOP Publishing
Date: 06-01-2011
DOI: 10.1088/0022-3727/44/4/045201
Abstract: A remote plasma chemical vapour deposition (RPCVD) system for the growth of gallium nitride (GaN) thin films is investigated using optical emission spectroscopy (OES). The intensities of the various excited species in pure nitrogen as well as nitrogen/hydrogen plasmas are correlated with GaN film growth characteristics. We show a correlation between the plasma source spectrum, the downstream spectrum where trimethylgallium is introduced and the GaN film quality. In particular, we investigate the addition of hydrogen, which greatly affects the gas phase species and the GaN film characteristics. OES is demonstrated to be a valuable monitoring tool in a RPCVD system for optimization of GaN growth.
Probing helium nano-bubble formation in tungsten with grazing incidence small angle x-ray scattering
Publisher: IOP Publishing
Date: 11-03-2015
D and D/He plasma interactions with diamond: Surface modification and D retention
Publisher: Elsevier BV
Date: 10-2014
Negative hydrogen ion production in a helicon plasma source
Publisher: AIP Publishing
Date: 09-2015
DOI: 10.1063/1.4931469
Abstract: In order to develop very high energy (& MeV) neutral beam injection systems for applications, such as plasma heating in fusion devices, it is necessary first to develop high throughput negative ion sources. For the ITER reference source, this will be realised using caesiated inductively coupled plasma devices, containing either hydrogen or deuterium discharges, operated with high rf input powers (up to 90 kW per driver). It has been suggested that due to their high power coupling efficiency, helicon devices may be able to reduce power requirements and potentially obviate the need for caesiation due to the high plasma densities achievable. Here, we present measurements of negative ion densities in a hydrogen discharge produced by a helicon device, with externally applied DC magnetic fields ranging from 0 to 8.5 mT at 5 and 10 mTorr fill pressures. These measurements were taken in the magnetised plasma interaction experiment at the Australian National University and were performed using the probe-based laser photodetachment technique, modified for the use in the afterglow of the plasma discharge. A peak in the electron density is observed at ∼3 mT and is correlated with changes in the rf power transfer efficiency. With increasing magnetic field, an increase in the negative ion fraction from 0.04 to 0.10 and negative ion densities from 8 × 1014 m−3 to 7 × 1015 m−3 is observed. It is also shown that the negative ion densities can be increased by a factor of 8 with the application of an external DC magnetic field.
A flowing plasma model to describe drift waves in a cylindrical helicon discharge
Publisher: AIP Publishing
Date: 04-2011
DOI: 10.1063/1.3581045
Abstract: A two-fluid model developed originally to describe wave oscillations in the vacuum arc centrifuge, a cylindrical, rapidly rotating, low temperature, and confined plasma column, is applied to interpret plasma oscillations in a RF generated linear magnetized plasma [WOMBAT (waves on magnetized beams and turbulence)], with similar density and field strength. Compared to typical centrifuge plasmas, WOMBAT plasmas have slower normalized rotation frequency, lower temperature, and lower axial velocity. Despite these differences, the two-fluid model provides a consistent description of the WOMBAT plasma configuration and yields qualitative agreement between measured and predicted wave oscillation frequencies with axial field strength. In addition, the radial profile of the density perturbation predicted by this model is consistent with the data. Parameter scans show that the dispersion curve is sensitive to the axial field strength and the electron temperature, and the dependence of oscillation frequency with electron temperature matches the experiment. These results consolidate earlier claims that the density and floating potential oscillations are a resistive drift mode, driven by the density gradient. To our knowledge, this is the first detailed physics model of flowing plasmas in the diffusion region away from the RF source. Possible extensions to the model, including temperature nonuniformity and magnetic field oscillations, are also discussed.
Ion beam formation in a low-pressure geometrically expanding argon plasma
Publisher: AIP Publishing
Date: 10-12-2007
DOI: 10.1063/1.2823575
Abstract: Supersonic ion beam formation has been observed in a geometrically expanding low-pressure inductively coupled argon plasma. It is found that the ion beam is only observed below 3mTorr and only when the discharge is operated in inductive mode. The geometrical expansion of the plasma induces density and potential gradients leading to the ion beam formation. The ion beam energy increases with decreasing source tube radius. The results show that ion beam formation can be achieved by geometrical expansion alone and that the ion beam energy depends on the ratio of the cross-sectional area of the source and expansion region.
Plasma parameters and electron energy distribution functions in a magnetically focused plasma
Publisher: AIP Publishing
Date: 03-2013
DOI: 10.1063/1.4794841
Abstract: Spatially resolved measurements of ion density, electron temperature, floating potential, and the electron energy distribution function (EEDF) are presented for a magnetically focused plasma. The measurements identify a central plasma column displaying Maxwellian EEDFs at an electron temperature of about 5 eV indicating the presence of a significant fraction of electrons in the inelastic energy range (energies above 15 eV). It is observed that the EEDF remains Maxwellian along the axis of the discharge with an increase in density, at constant electron temperature, observed in the region of highest magnetic field strength. Both electron density and temperature decrease at the plasma radial edge. Electron temperature isotherms measured in the downstream region are found to coincide with the magnetic field lines.
Negative ions in single and dual frequency capacitively coupled fluorocarbon plasmas
Publisher: IOP Publishing
Date: 31-01-2007
Transition from unstable electrostatic confinement to stable magnetic confinement in a helicon reactor operating with Ar∕SF6 gas mixtures
Publisher: AIP Publishing
Date: 15-05-2006
DOI: 10.1063/1.2191431
Abstract: Two types of instabilities were previously identified in inductive discharges having an expanding chamber when negative ions are present: (i) the source instability, occurring in the neighborhood of the capacitive-to-inductive (E to H) transition, and (ii) the downstream instability, which was shown to be the periodic formation and propagation of double layers. These unstable double layers were found over the entire parameter space (pressure ower) of interest, and they were born at the interface of the source and diffusion chambers. They acted as an internal electrostatic barrier separating a low-electronegativity, high-electron-density plasma upstream (in the source) and a high-electronegativity, low-electron-density plasma downstream. In this paper we have investigated the effect of adding a static axial magnetic field, classically used to increase the confinement and the plasma heating via helicon wave propagation. This had the following consequences: (i) the unstable double layers, and therefore the axial electrostatic confinement, were suppressed in a large part of the parameter space, and (ii) the magnetic confinement leads to a radially stratified plasma, the center being a low-electronegativity, high-density plasma and the edges being essentially an ion-ion plasma.
Fluorine negative ion density measurement in a dual frequency capacitive plasma etch reactor by cavity ring-down spectroscopy
Publisher: AIP Publishing
Date: 10-04-2006
DOI: 10.1063/1.2194823
Abstract: F − negative ions were detected by direct observation of the weak photodetachment absorption continuum below 364.5nm by cavity ring-down spectroscopy. The negative ions were generated in a modified industrial dielectric plasma etch reactor, with 2+27MHz dual frequency capacitive excitation in Ar∕CF4∕O2 and Ar∕C4F8∕O2 gas mixtures. The F− signal was superimposed on an unidentified absorption continuum, which was diminished by O2 addition. The F− densities were in the range of (0.5–3)×1011cm−3, and were not significantly different for single (27MHz) or dual (2+27MHz) frequency excitation, not confirming recent modeling predictions.
Investigation of He–W interactions using DiMES on DIII-D
Publisher: IOP Publishing
Date: 21-01-2016
Ion irradiated graphite exposed to fusion-relevant deuterium plasma
Publisher: Elsevier BV
Date: 12-2014
Measuring helium bubble diameter distributions in tungsten with grazing incidence small angle x-ray scattering (GISAXS)
Publisher: IOP Publishing
Date: 08-01-2016
Observation of a helium ion energy threshold for retention in tungsten exposed to hydrogen/helium mixture plasma
Publisher: IOP Publishing
Date: 16-08-2016
DOI: 10.1088/0029-5515/56/10/104002
Abstract: Helium retention is measured in tungsten s les exposed to mixed H/He plasma in the Magnum-PSI linear plasma device. It is observed that there is very little He retention below helium ion impact energies of 9.0 ± 1.4 eV, indicating the existence of a potential barrier which must be overcome for implantation to occur. The helium retention in s les exposed to plasma at temperatures K is strongly correlated with nano-bubble formation measured using grazing incidence small-angle x-ray scattering. The diameters of nano-bubbles were not found to increase with increasing helium concentration, indicating that additional helium must be accommodated by increasing the bubble concentration or an increase in bubble pressure. For some s les pre-irradiation with heavy ions of 2.0 MeV energy is investigated to simulate the effects of neutron damage. It is observed that nano-bubble sizes are comparable between s les pre-irradiated with heavy-ions, and those without heavy-ion pre-irradiation.
Generation of underwater discharges inside gas bubbles using a 30-needles-to-plate electrode
Publisher: AIP Publishing
Date: 20-10-2017
DOI: 10.1063/1.4993497
Abstract: Underwater discharges inside helium (He) gas bubbles were generated using a 30-needles-to-plate electrode system with the gas flowing through the needles. The set-up allows continuous treatment of flowing water. The plasma electron temperature and density determined from spectral line intensities and profiles of the Hα and Hβ hydrogen lines were found to be 1.1 ± 0.6 eV and ∼5 × 1016 cm−3, respectively. These parameters are comparable with those of plasmas generated by other underwater gas bubble discharges for the production of OH radicals. The two main long-lived species, hydrogen peroxide (H2O2) and nitrate ions (NO3−), produced in plasma treated water were measured. It was found that without a continuous water flow, the energy yield of H2O2 was comparable with other underwater discharges, while with a continuous flow, the production of H2O2 appeared to be somewhat reduced by nitrites from dissolved air.
A volume-averaged model of nitrogen–hydrogen plasma chemistry to investigate ammonia production in a plasma-surface-interaction device
Publisher: IOP Publishing
Date: 04-06-2018
Plasma treated water – A promising electrolyte to produce nanoporous titanium dioxide nanotubes
Publisher: Wiley
Date: 02-2017
Bidirectional vortex stabilization of a supersonic inductively coupled plasma torch
Publisher: IOP Publishing
Date: 24-02-2023
Abstract: Radio-frequency (RF) inductively coupled plasma (ICP) torches using a supersonic nozzle have many industrial materials processing applications and have also been proposed as novel electrothermal plasma thrusters for space propulsion. The gas injection method in plasma torches plays an important role in both gas heating dynamics and overall discharge stabilization. Here, we investigate reverse vortex gas injection into a supersonic ICP torch for RF powers up to 1 kW, argon mass flow rates between 15 and 180 mg s −1 , and plasma torch pressures from ∼270 Pa to ∼50 kPa. In this configuration, gas is injected tangentially just upstream of the nozzle inlet. This produces a bidirectional vortex flow field where gas first spirals upwards along the outer edge of the plasma torch walls, before then reversing direction at the torch end and spiralling back down through the central plasma region towards the nozzle exit. Results are compared to a more conventional forward vortex configuration where gas is instead injected tangentially from the upstream end of the torch, and which forms a unidirectional vortex that spirals towards the downstream nozzle. While performance is similar for gas flows below 80 mg s −1 , we show that at higher mass flow rates both the effective torch stagnation temperature and thermal efficiency can be increased by almost 50% with reverse vortex injection. Considering that the measured RF antenna-plasma power transfer efficiency is similar for both configurations, this enhancement occurs because of the unique bidirectional vortex flow field which leads to reduced gas-wall heat losses and consequently an increased enthalpy flow leaving the torch.
GISAXS modelling of helium-induced nano-bubble formation in tungsten and comparison with TEM
Publisher: Elsevier BV
Date: 05-2016
High Water Diffusivity in Low Hydration Plasma-Polymerised Proton Exchange Membranes
Publisher: Trans Tech Publications, Ltd.
Date: 06-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.654-656.2871
Abstract: This paper compares proton diffusion through plasma-polymerised proton-exchange membranes (PEMs) produced using traditional wet-chemical methods (Nafion®) and those produced using plasma-polymerisation. Using quasielastic neutron scattering and a simple model of proton motion we find the measured diffusion-rate of protons in the plasma-polymerised material and Nafion® is the same (within 1 standard error) even though the plasma-polymerised membrane has 80 % less water than the Nafion®. We attribute this result to the highly cross-linked structure of the plasma-polymerised membrane.
Related Organisations
Queen's University Belfast
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
ARC Future Fellowships - Grant ID: FT100100825
Start Date: 01-2011
End Date: 01-2015
Amount: $680,552.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200102830
Start Date: 07-2020
End Date: 12-2023
Amount: $405,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE120100021
Start Date: 01-2012
End Date: 12-2013
Amount: $150,000.00
Funder: Australian Research Council
View Funded Activity