Modelling of High Intensity Arcs Including a Non-Equilibrium Description of the Cathode Sheath

Abstract

M : Un mod&le a 6t6 cEvelopp6 pour la prediction d'arcs Bectriques h forte intensit6 et h pression atmosph6rique. Le code M6lodie (diff6rences finies orthogonales) nous a permis de rksoudre le syst&me coup16 d'6quations thermodynamiques et 6lectromagn6tiques incluant effet JOULE et forces de LORENTZ. Dans la colonne cl'arc laminaire, les 6quations sont Ccrites en hypoth2se d'6quilibre thennodynamique local @.TL.), et avec l'approximation de la loi #OHM. Les conditions aux limites h la cathode sont d6terminks B pa& d'un modkle mono-dimensiomel de couche limite cathodique en &&uilibre thermodynamique, coup16 de plus avec le calcul du transfert thermique dans l'6lectrode solide. Les calculs men& dans le cas d'arcs libm ou d'arcs tranf6rCs dans l'argon, avec une cathode wnique en tungsene, ont montr6 un bon accord avec les mesures.: An axisymetric model has been developed for prediction of high intensity electric arcs under atmospheric pressure. A set of thennodynamic and electromagnetic equations, including interaction terms (JOULE effect, LORENTZ forces) is solved using the orthogonal finite difference numerical code M6lodie. Conservation equations in the laminar arc column (mass, momentum, energy and current) are written according to the local thermodynamic equilibrium (L.T.E.) assumption and the OHM law approximation. The proper boundary condition at the cathode is derived from a onedimensional description of non-equilibrium electrode boundary layer, coupled with full computation of heat transfer in solid region (conic cathode in tungsten). Numerical calculations performed for free burning and t r a n s f d argon arcs show a good agreement with experimental data. NOMENCLATURE a subscript of the different specie of the T plasma temperature (K) ..

Analysis of energy exchanges during the interaction between pulsed lightning arcs and metallic plates

“…Many other works have dealt with the energy balance at the arc-electrode interface for a variety of arc applications as, for instance, welding, cutting, circuit-breakers, furnaces, high-intensity discharge (HID) lamps, etc. [7][8][9][10][11][12][13][14][15][16][17][18][19][20] To mention a few examples, Benilov et al [7][8][9][10] have performed many studies on the modelling of plasma-electrode interaction in HID lamps from the earlies 90's, with current amplitudes starting from around 1 A to a few hundreds of amperes. Hsu et al 11 , Delalondre and Simonin 12 , Lowke et al 13 and Lago et al 14 deal with the same category of plasma-electrode models in the context of DC arcs in argon plasmas with current ranging from 50 to 400 A, which can be found in cutting and furnace applications.…”

A mathematical model of gas tungsten arc welding considering the cathode and the free surface of the weld pool

“…[3] A model without any assumption of the current density at the cathode surface was presented until recently, [9,10,11] and Fan et al [12] used a similar model to describe the heat and mass transfer in pulsed GTA welding.…”

Detection of the clock transition (1.14 μm) in ultra-cold thulium atoms

“…The thickness of these transition layers is of the order of 100 µm (e.g. Hsu et al 1983, Delalondre and Simonin 1990, Morrow and Lowke 1993, Benilov 1997.…”