Analytical Solving a Nonlinear Model of the Glow Discharge

A nonlinear model has been introduced for the positive column of DC glow discharge in apure sealed, or low flow, gas media by including the diffusion, recombination, attachment, detachment,process and having the two-step ionization process of the metastable excited states, too. By thecombination of the system of the nonlinear continuity equations of the system, using some physicalestimations, and degrading the resulted nonlinear PDE in polar and rectangular systems of coordinatethe steady-state nonlinear ODE have been derived. Using a series-based solution, an innovativenonlinear recursion relation has been proposed for calculating the sentence of series. Using the stateof elimination of free charge on the outer boundary of the discharge vessel, the universal equation ofthe characteristic energy of the electrons versus the similarity variable, using the maximum degree ofionization as the parameter, has been derived.

Influence of the filling gas mixture on the interruption capability of medium voltage load break switches

In today’s medium voltage switchgear SF6 is commonly used as insulating and arc quenching medium. Because of its high potential impact on the environment a substitution with an environmentally friendly alternative is pursued. In this paper the influence of the mixing ratio of carbon dioxide nitrogen mixtures as filling gas on the interruption capability in medium voltage load break switches is investigated. The interruption capability is regarded by means of the thermal interruption performance as well as the dielectric recovery of a model load break switch. The model load break switch allows an axial arc blowing with variable pressure and uses an exchangeable nozzle system.

Arc extinction with nitrogen at 1-40 bar in a puffer-like contact configuration

To develop cost-efficient subsea switchgear for large sea depths, the extinction of arcs under high filling pressures must be understood. In this work, arc-extinction experiments have been performed with a puffer-like contact configuration using nitrogen at different filling pressures as the current interruption medium. The main finding is that, for the given contact configuration, the currentinterruption capability was lower at 20 and 40 barabs than at 1 and 10 barabs. While higher pressures result in higher cooling flow rates and longer flow times given the same puffer volume, compression spring and nozzle geometry; it does not necessarily improve the arc-extinction capability. This is probably because higher filling pressures increase the arc voltage and total energy dissipated in the arcing zone. Because the filling pressure greatly influences the flow characteristics, the puffer design should be optimized for each pressure level.

On the stimulation of the de-excitation of nuclear isomers in plasma of a high-current electric discharge

The prospects of stimulated de-excitation of nuclear isomers (SDENI) with a trigger transition energy ∆E up to ∼ 1 keV in a plasma of a high-current electric discharge (HCED) with an electron temperature θ ∼ ∆E are discussed. An estimate of the probability of the SDENI process in plasma by the mechanism of nuclear excitation by electron capture (NEEC) is obtained. Themost promising for the SDENI study are isomers 229mTh (∆E ≈ 8 eV), 235mU (∆E = 76 eV), 110mAg (∆E = 1128 eV). To create an energy source most promising isomer is 186m Re (∆E is unknown) with a half-life of 2 × 105y, for which stimulated de-excitation in the laser plasma had beenalready observed at θ ∼ 1 keV.

Unified modelling of TIG microarcs with evaporation from copper anode

A previously developed unified model of a tungsten-inert gas (TIG) microarc has been extended to take into account the melting of the anode made of copper and the release of copper atoms due to its evaporation. The copper atoms enter the plasma to become excited and ionized. The presence of copper atoms and ions can strongly change the plasma parameters. The extended unified model further includes excited states of copper and collisional and radiative processes between them. Predictions of the parameters of the microarc plasma in the presence of copper species are presented and discussed.

Influence of solution properties and gas addition on hydrogen peroxide production by a novel plasma source

The paper evaluates concentration of hydrogen peroxide produced by a novel pin-hole plasma source in electrolyte solutions with or without gas addition. An effective production rate of hydrogen peroxide is decreased by the increased argon as well as oxygen flow rate through the plasma region. Further, it is enhanced by higher solution conductivity while it is decreased in the strongly basic conditions with the highest pH values.

Time evolution of the process of doping of solids by plasma-ion beams

Irradiation of a solid with intense plasma-ion beams produced within a high vacuumchamber (by the so-called Rod Plasma Injector [1]) is a strongly nonequilibrium process, which enablesachieving a number of effects which are impossible to be achieved with other methods. These are,amongst other: improvement of ceramics wettability, fabrication of stable copper-ceramics interfacesand stable Ni-Cu and Al-Cu interfaces, improvement of tribological properties and high temperatureoxidation resistance of stainless steel, photovoltaic junction formation, and many others. In the paper,the process of plasma-ion beam propagation regarding its time and energy distributions and the processof ion penetration of solids, resulting with ion implementation and temperature growth have beenanalyzed mathematically on basis of experimental data. Results of numerical calculations have beenpresented concerning temperature and dopant density time evolution.

0D KINETIC MODEL: APPLIED TO SF6

This work is related to the chemical kinetics modelling of plasma during extinction. A zero-dimensional model (0D) has been developed. Two hypotheses were used: (A) a constant pressure or (B) a constant mass density. Three initial data categories are generally required for the model: (1) the chemical reactions that govern the kinetic scheme, (2) the chemical composition at the local thermodynamic equilibrium (LTE) and (3) a law of temperature decay as a function of time representing the cooling rate. The developed model is presented and applied to SF6, gas commonly used in high voltage circuit breakers (HVCB), in order to be validated. We present the evolution of the species during the temperature decay for several cooling rates. The results give the evolution of species densities and the departures from equilibrium according to the cooling rate. Consideration of SFx molecules is essential in order to avoid erroneous interpretations.

Thermal Plasma of Electric Arc Discharge Between Composite Cu-Cr Electrsodes: Optical Emission and Electrode Surface Interaction

This work deals with investigations of thermal plasma of electric arc discharge between sintered composite Cu-Cr electrodes, which can be used in electrical contacts of vacuum circuit breakers. Breaking arcs between composite Cu-Cr as well as single-component copper electrodes were used to study the electrical properties, plasma optical emission and electrodes surface modification behavior. In particular, the temporal evolution of plasma emission spectra of electric breaking arcs in air atmosphere was investigated by Optical Emission Spectroscopy (OES). Scanning Electron Microscopy (SEM) with Energy-dispersive X-ray Spectroscopy (EDXS) were applied to analyze the cross-section of working layer of electrodes surface modified by the heat flux from the discharge.

Electron Induced Emission of Nitrous Oxide in the UV-VIS Spectral Range

The electron impact excitation of N2O was studied using the crossed electron-molecular beams method. Optical emission spectrum initiated by 50 eV electron impact was recorded within the range 200-700 nm. Main emission bands arise from excited ion state N2O+(A2Σ) and dissociative excitation into N2+(B2Σ+u). The rotationally un-resolved excitation-emission cross sections for selected ion transitions were scaled to absolute values and their dependence on electron energy was determined. Several of them were determined for the first time.