Surface modifications of TiN coating by pulsed ir lasers: tea CO2 and HF laser

Interactions of a pulsed Transversely Excited Atmospheric (TEA) CO2 and chemical HF laser with polycrystalline titanium nitride (TiN) coating deposited on high quality steel AISI 316, were studied. It was shown that both lasers, at energy densities of 43 J/cm2 and 38.6 J/cm2, induce morphological changes on the target. The HF laser produces more pronounced damage than the TEA CO2 laser. The energy absorbed from either of these lasers is mainly converted into thermal energy.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Computational and experimental study of time-averaged characteristics of positive and negative DC corona discharges in point-plane gaps in atmospheric air

The use of stationary solvers instead of approximate solution methods or time-dependent solvers, which are standard tools in gas discharge modeling, allows one to develop a very fast and robust numerical model for studying the time-averaged characteristics of dc corona discharges. Such an approach is applied to dc corona discharges in point-plane gaps in ambi ent air. A wide range of currents of both voltage polarities and various gap lengths are investigated, and the simulation results are validated by comparing the computed current–voltage characteristics and spatial distributions of the radiation intensity with experimental results. Specific features of the numerical and experimental results at both polarities are discussed.info:eu-repo/semantics/publishedVersio

Methods for recording the time profile of single ultrashort pulses of electron beams and discharge currents in real-time mode

The collectors for measuring the time profile of a current pulse of the runaway electron beam that are generated under atmospheric pressure are described. An analysis of changes in pulse shape depending on the bandwidth of the registration path with a temporal resolution of up to 20 ps was performed. It is shown that the electron beam detected behind small-diameter diaphragms has a complex structure, which depends on the parameters of the gas diode. There is a design of the current shunts with a temporal resolution of up to 100 ps in this study. Measurement techniques of voltage pulses with subnanosecond and nanosecond duration are briefly described

Subnanosecond high-voltage breakdown initiated in high-pressure nitrogen by a runaway electron beam

This study reports on subnanosecond breakdowns initiated on high pressure nitrogen by a runaway electron beam in an inhomogeneous electric field. It is shown that a diffuse discharge with a duration of ≥1 ns is formed in the gas diode. Data are reported for the first time on collector measurements of a supershort avalanche electron beam downstream of an anode foil at a nitrogen pressure of 0.5–1.2 MPa. The beam pulsewidth at these pressures is ∼90 ps. At a nitrogen pressure of 1.2 MPa, the number of electrons with an energy >70 keV recorded by the collector is 4 × 10^6/cm^2