Browsing by Author "Risso, Marcelo Natalio"

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    Desarrollo de una antorcha de plasma de arco no-transferido.
    (UTN FRVT, 2013) Infante, Damián Leandro; Risso, Marcelo Natalio; Alí, Daniel; Ferreyra, Daniel
    El proyecto abarca el diseño de una antorcha de arco no transferido de = 300 A, pasando por la elección del sistema de generación y estabilización del arco, el reacondicionamiento del circuito eléctrico de alimentación e igncición del arco, el diseño del sistema de inyección de gases junto al circuito de refrigeración; hasta la construcción del modelo de antorcha elegido.
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    On the dynamic behavior of the anode–arc–root at the nozzle surface in a non-transferred plasma torch
    (2012) Prevosto, Leandro; Risso, Marcelo Natalio; Infante, Damián Leandro; Cejas, Ezequiel; Kelly, Héctor; Mancinelli, Beatriz
    The dynamic behavior of the anode–arc–root at the nozzle surface of a plasma torch was experimentally investigated in this work. A gas (N2) vortex–stabilized non–transferred arc torch with a thoriated tungsten rod (2wt %) cathode (3.2 mm diameter) and a coaxial anode (5 mm diameter, 30 mm length) was used in the experiment. By using a sweeping Langmuir probe in floating condition, the voltage of the plasma jet outside the nozzle was inferred. Arc voltage waveforms were also obtained. Data have been obtained for an arc current of 100 A and a gas flow rate of 30 Nl min-1. A typical sawtooth shape (i.e., restrike mode) (with a fluctuating level of º  25 %) and a dominant frequency of º 6.5 kHz was observed in the arc voltage waveforms, which is attributed to anode–arc–root movements along the anode surface followed by a restrike at a certain point close to the cathode. By performing a time correlation between the probe and arc voltage oscillograms together with simple estimations, the amplitude of the movement of the arc–root along the anode surface as well its velocity were inferred.
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    On the influence of the nozzle length on the arc properties in a cutting torch
    (2009) Prevosto, Leandro; Kelly, Héctor; Risso, Marcelo Natalio; Infante, Damián Leandro
    In this work, an experimental study on the influence of the nozzle geometry on the physical properties of a cutting arc is reported. Ion current signals collected by an electrostatic probe sweeping across a 30 A oxygen cutting arc at 3.5 mm from the nozzle exit were registered for different nozzle lengths. The temperature and density radial profiles of the arc plasma were found in each case by an inversion procedure of these signals. A comparison between the obtained results shows that the shorter nozzle (RN = 0.50 mm, LN = 4.5 mm operated at 0.7 MPa and 35 Nl/min) produces a thinner and hotter arc than the larger nozzle (RN = 0.50 mm, LN = 9.0 mm operated at 1.1 MPa and 20 Nl/min). This behavior is attributed to the marked difference of gas flow rate due to the clogging effect. A smaller gas mass flow reduces the convective cooling at the arc border and decreases the power dissipation of the arc column, resulting in small axis temperatures.