René Demellayer

Bio: René Demellayer is an academic researcher. The author has contributed to research in topics: Electrical discharge machining & Electron temperature. The author has an hindex of 1, co-authored 1 publications receiving 65 citations.

Optical emission spectroscopy of electrical discharge machining plasma

Abstract: Plasma created during electrical discharge machining is systematically investigated using optical emission spectroscopy. Typical spectra show a strong H-alpha and continuum radiation, with many lines emitted by impurities coming from electrode and workpiece materials. The dielectric molecules are cracked by the discharge. Changing polarity affects the electrode wear and workpiece erosion rates, which can be qualitatively seen on the spectra. Time-resolved spectroscopy shows that the plasma density reaches 2 x 10(18) cm(-3) at the beginning of the discharge. This extreme density causes the merging of lines, strong Stark broadening and shift of the H-alpha line. Afterwards, the density decreases rapidly with time. The electron temperature remains roughly constant around 0.7 eV. The low temperature and the high density measured prove that the EDM plasma is non-ideal (Gamma similar or equal to 0.45). Absence of the H-beta line, asymmetric shape of the H-alpha line and complex structures around H-alpha are other spectroscopic evidences of the plasma non-ideality.

Atmospheric-pressure plasma technology

Abstract: Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

Modeling of a Single Resistance Capacitance Pulse Discharge in Micro-Electro Discharge Machining

Abstract: Micro-EDM (electro discharge machining) is a derived form of EDM process especially evolved for micro-machining. The use of resistance capacitance pulse generator, an advanced controller for machining in smaller interelectrode gaps and with lower discharge energies than in EDM, makes the material removal characteristics of a single discharge in micro-EDM different from that of the EDM. A comprehensive model predicting the material removal in a single discharge in micro-EDM is conceptualized. The model incorporates various phenomena in the prebreakdown period. It considers plasma as a time-variable source of energy to the cathode and anode to evaluate material removal at the electrodes. The plasma temperature and radius of the crater at the cathode (workpiece) predicted using the model were found to agree well with the experimental data in the literature.

Optical emission spectroscopy of Ar-N2 mixture plasma

Abstract: Optical emission spectroscopy measurements are presented to characterize the different excitation and ionization processes of both atomic and molecular species in Ar–N2 mixture plasma under different discharge conditions. Particularly, the emission intensities of nitrogen (0–0) band of second positive system at 337.1 nm and (0–0) band of first negative systems at 391.4 nm are used to determine the dependence of their radiative states [ N 2 ( C 3 Π u ) , N 2 + ( B 2 Σ u + ) ] on argon fraction in the mixture. It is observed that the addition of argon gas influences the radiative states differently due to their different populating mechanisms. The results demonstrate that the addition of argon to nitrogen plasma remarkably enhance the population of N 2 ( C 3 Π u ) radiative state through Penning excitation involving argon metastable states. The electron temperature is determined from Ar-I spectral line intensities, using Boltzmann's plot method and is found to depend on argon fraction in the mixture.