DIFFER: Publications
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Electron density evolution during a fast, non-diffusive propagation of a magnetic field in a multi-ion-species plasma
No full textInvestigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation
No full textArcing on fiber-formed nanostructured tungsten samples during ELM-like pulses was investigated using the superimposition of high power pulsed plasma on a steady state plasma with hydrogen gas in the linear plasma device Pilot-PSI. The ignition of arcing was observed when the floating potential of the samples was less than −75 V with sufficient heat flux. The surface observation showed that the arc spots were not in the center, but in the peripheral area of the plasma column. Considering the plasma potential profile in the Pilot-PSI, the arcing occurred at the position where the heat flux and the sheath potential drop are sufficiently large
Expanding Thermal Plasma Deposition of Al-Doped ZnO: On the Effect of the Plasma Chemistry on Film Growth Mechanisms
No full textThis work presents a review of expanding thermal plasma – chemical vapour deposition (ETP-CVD) of Al-doped ZnOtransparent conducting oxides (TCOs), alongside new results providing insights into the role of the plasma chemistry on film microstructure. Standard growth conditions generate high resistivities (>10−3ohm cm) at low film thicknesses (<300 nm) as a result of a high grain boundary and void density. Microscopy studies of the early growth stage reveal that a high nucleation probability and strong <0002>-texture are the causes of this microstructure. We investigate how the precursor feed composition (diethylzinc-to-O2 flow rate ratio) can be utilised to modify the growth mechanism and consequently reduce film resistivity (∼10−4ohm cm), focussing on the role that this flow rate ratio has on the plasma chemistry developing in the downstream region of the expanding plasma (as supported by Langmuir probe and mass spectrometry measurements).</p
Dielectric barrier discharges revisited: the case for mobile surface charge
Get PDFWe propose a mechanism to explain many features of the multi-filament dielectric barrier discharge: while part of the charge deposited during previous discharge cycles is immobile on the dielectric over time periods of seconds, the larger fraction of the deposited charge must be mobile on time-scales of hundreds of ns. For alumina, we estimate that a sheet resistance of 3 MΩ sq −1 is consistent with the multi-filament discharge; an increase in conductivity of at least 12 orders of magnitude. The existence of this type of plasma-induced surface conductivity could prove relevant in modeling a wide range of plasma devices, in addition to DBD.</p
Gas-Phase Plasma Synthesis of Free-Standing Silicon Nanoparticles for Future Energy Applications
No full textSilicon nanoparticles (Si-NPs) are considered as possible candidates for a wide spectrum of future technological applications. Research in the last decades has shown that plasmas are one of the most suitable environments for the synthesis of Si-NPs. This review discusses the unique size-dependent features of Si-NPs, and the fundamental mechanisms of nanoparticle formation in plasmas by highlighting major plasma synthesis techniques. In addition, the routes to achieve control on Si-NP morphology and chemistry in plasma environments will be discussed. We will review recent advancements in solar cell and lithium-ion battery applications of gas-phase plasma synthesized Si-NPs by highlighting key results from the literature. We will discuss further technological applications, where gas-phase plasma synthesized Si-NPs can contribute, like water splitting and thermoelectrics.</p
Exploring the electron density in plasma induced by EUV radiation: II. Numerical studies in argon and hydrogen
No full textWe used numerical modeling to study the evolution of EUV-induced plasmas in argon and hydrogen. The results of simulations were compared to the electron densities measured by microwave cavity resonance spectroscopy. It was found that the measured electron densities can be used to derive the integral amount of plasma in the cavity. However, in some regimes, the impact of the setup geometry, EUV spectrum, and EUV induced secondary emission should be taken into account. The influence of these parameters on the generated plasma and the measured electron density is discussed.</p