Temperature Distribution Of Arc Plasma Research Articles

Tomographic measurement of current density and heat input density for tilting TIG arc

Heat source characteristics in the arc welding process such as temperature distribution of arc plasma, the current and heat input densities to the base metal is very important since they are one of...

Tomographic measurement of current density and heat input density for tilting TIG arc

ABSTRACT Heat source characteristics in the arc welding process such as temperature distribution of arc plasma, the current and heat input densities to the base metal is very important since they are one of the upstream factors of the process. Many studies have reported the distribution of temperature and metal vapour concentration in welding arc plasma by emission spectroscopy, and the distribution of heat input density to the base metal by split copper anode plate method. These studies generally require the axisymmetric assumption of the arc plasma. However, actual welding arcs are not limited as axisymmetric phenomenon. For example, tilted TIG arc welding is often performed due to the visibility and some reasons, resulting in a non-axisymmetric phenomenon in production sites. In order to measure such target, a tomographic approach is necessary. In this study, multidirectional measurement system with rotary split copper anodes was constructed to measure the non-axisymmetric distribution of the current and heat input densities of tilted TIG arc plasma. Integral values are measured from four directions and converted into a two-dimensional distribution by the image reconstruction method. It was experimentally revealed that as the tilting angle increases, the maximum value of current and heat input density decreases and the low density region of the distribution spreads towards the aiming direction. Although the measurement method using split anode including this study possesses the problem of arc deflection the insulating gap of split part, we found the fitting process on the measured data is useful to reduce this effect.

Measurement of temperature and electrons density distribution of atmospheric arc plasma by moiré deflectometry technique

In the present paper, the refractive index, electron density and temperature distribution of atmospheric arc plasmas are measured by moiré deflectometry. The deflection angle of rays passing through the plasma is obtained by moiré fringe analysis. Then by using inverse Abel transform integral for this axisymmetric plasma, the refractive index distribution is obtained in different points of plasma and environment. Considering the relation between plasma temperature and refractive index, the spatial temperature distribution of the arc plasma is evaluated. Also, in contrast to conventional models to obtain electron number density, in which the refractive index of plasmas is approximately assumed equal to the electron refractive index, a model is used for accurate and absolute measurement of the electron density profile. This technique is especially suitable for measuring axially symmetric plasma parameters.

ティグ溶接におけるプラズマ温度場と金属蒸気濃度場の挙動解析

In arc welding, heat source property of arc plasma depends on temperature of arc plasma. Temperature distribution of arc plasma is affected by metal vapor which evaporate from molten metal. In this paper, dynamical temperature distribution during TIG welding is obtained through optical measurement with a high speed video camera. Furthermore, spectral images of metal vapor are taken simultaneously, therefore distributions of metal vapor are also obtained. Temperature of arc plasma decreases with mixing metal vapor into the arc plasma. Manganese vapor, namely the metal which has low boiling point, is distributed widely, and concentration is high. On the other hand, iron vapor, namely the metal which has high boiling point, is distributed only near the center of the arc, and concentration is low.

Electrical Conductivity and Temperature Distribution of Arc Plasma in Narrow Insulating Channels

Having examined electrical conductivity and temperature distribution of a cross-section of an arc plasma column burning in the narrow channel between insulating walls. It was shown that arc pressure created by intrinsic magnetic field has little effect at subsonic velocity. In contrast with an open arc with convective cooling, mean electrical conductivity of an arc in a narrow channel is significantly dependent on the current passing through it.