Paper Title:
Predictions of Current Attachment at Thermionic Cathode for TIG Arcs
  Abstract

Study of current attachment at thermionic cathode for TIG arc at atmospheric pressure is attempted from numerical calculations of arc-electrodes unified model. The calculations show that the maximum temperature of arc plasma close to the cathode tip for W-2% ThO2 reaches 19,000 K and it is the highest value in comparison with the other temperatures for W-2% La2O3 and W-2% CeO2, because the current attachment at the cathode tip is constricted by a centralized limitation of liquid area of ThO2 due to its higher melting point. The calculations also show that, in cases of W- 2% La2O3 and W-2% CeO2, the liquid areas of La2O3 and Ce2O3 are widely expanded at the cathode tip due to their lower melting points and then produce uniform current attachments at the cathode. It is concluded that the current attachment at thermionic cathode is strongly dependent on work function, melting point and Richardson constant of emitter materials.

  Info
Periodical
Materials Science Forum (Volumes 580-582)
Edited by
Changhee Lee, Jong-Bong Lee, Dong-Hwan Park and Suck-Joo Na
Pages
319-322
DOI
10.4028/www.scientific.net/MSF.580-582.319
Citation
M. Tanaka, K. Yamamoto, S. Tashiro, J. J. Lowke, "Predictions of Current Attachment at Thermionic Cathode for TIG Arcs", Materials Science Forum, Vols. 580-582, pp. 319-322, 2008
Online since
June 2008
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Price
$32.00
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