Published 4 issues per year
ISSN Print: 1093-3611
ISSN Online: 1940-4360
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Modelling of plasma dynamics in coaxial IPD accelerator
ABSTRACT
This paper presents the results of physico-mathematical modelling of plasma dynamics in a coaxial accelerator for IPD (Impulse Plasma Deposition) process. Metallic plasma is generated within the working gas due to electric discharge, ignited within inter-electrode region. Plasma spreads out in the form of a dynamically moving electric current sheet which is accelerated by the Lorentz force. Conditions favourable for evaluation of the Rayleigh-Taylor instability on the current sheet surface have been found during the computational studies of plasma movement. Appearance of this phenomenon explains non-uniform phase composition and morphology of coatings. By modifying the design of the plasma accelerator, we succeeded in reducing substantially R-T instability and in obtaining alpha-Al2O3 coatings instead of common gamma-Al2O3.
Proposed model, which is still being modified, does not yet take into account the effect of plasma being enriched with the products of the electrodes erosion. Nevertheless preliminary results have been obtained, accounting for the influence of eroded material on the dynamics of the discharge. Even at this stage the results of computer simulation are in semi-quantitative agreement with experimental observations.