Large effect of cathode shape on plasma temperature in high-current free-burning arcs

Abstract

The temperatures of the cathode surface and of the plasma for an atmospheric-pressure high-current free-burning argon arc have been measured for a range of cone angles for cathodes of thoriated tungsten. These measurements have shown that both the surface temperature of the cathode and the temperature of the plasma depend strongly on the cathode shape. For cathodes with conical shape, plasma temperatures were found to be a maximum for a cathode cone angle of 60 degrees .

Effect of Anode Heat Transfer on Melted Penetration in Welding Process by Free-burning Argon Arc.

“…A difference of electron temperature between a cathode conical angle of 45°and 60°is about 3 000 K. This tendency agrees with the result of arc pressure. 20) Haidar and Farmer 17) showed that temperatures were found to be maximum for a cathode conical angle of 60°. It is because the temperature for a cathode conical angle of 45°was not measured in their experiments.…”

“…Changing a cathode conical angle resulted in changes in the surface temperature of cathode which changed the root size of the arc-cathode attachment region. 17) As a result, in the plasma surrounding the cathode, it was seemed that there was a change in the current density and the plasma temperature.…”

Anode heat transfer in TIG welding and its effect on the cross-sectional area of weld penetration

“…Haidar et al have measured the arc plasma temperature by emission spectroscopic analysis of generated plasma and have shown this temperature to depend on the cathode conical tip angle. 32 These authors regard the foregoing behaviour as being linked to variation in the energy balance of the arc/cathode system due to variation in the cathode conical tip angle, consequently to variation in the distribution of thermionic current discharged from the cathode in response to the cathode surface temperature, i.e. to 33 The maximum arc pressure measured at the anode surface operates as an inertia force as the cathode jet (plasma flux) generated by the electromagnetic pinching effect near the cathode changes direction towards the radial direction at the anode surface, and it is no exaggeration to say that arc phenomena near the cathode are fully reflected as they stand.…”

An experimental study of thoriated tungsten cathodes operating at different current intensities in an atmospheric-pressure plasma torch

“…Our goal in the present paper is to investigate the behaviour of these cathodes over a wide range of arc current intensities. Thoriated tungsten cathodes have been experimentally studied by different authors [1][2][3][4][5][6][7][8][9][10][11], but in most of the studies, the cathodes were operated with only a few current intensities; therefore, the dependences of the cathode parameters on the arc current intensity I were not found.In the present paper, we discuss our experimental investigation of thoriated tungsten cathodes operating in the actual working conditions of an industrial plasma torch. We used arc current intensities ranging from 30 A to 200 A, which allows the investigation of cathode…”