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THIN BARIUM LAYER FORMATION AND ITS INFLUENCE ON TUNGSTEN ELECTRODE ARC ATTACHMENT MODES IN HID LAMPS

M. Cristea1,* , G. Zissis2

Affiliation

  1. "Politehnica" University of Bucharest, Physics Department, Splaiul Independentei 313, 77206 Bucharest, Romania
  2. Paul Sabatier University of Toulouse, Centre for Plasma Physics and Applications of Toulouse, Route de Narbonne 118, Toulouse, France

Abstract

In this paper the influence of electric field, voltage drop and Schottky corrected work function on thin barium monolayer regarding the diffuse or hot-spot formation in the refractory cathode are analysed. Using the thermal flux continuity equation the hot-spot dimension is calculated. Based on the energy balance equation, a 3D model for getting the temperature distribution in the bulk of high-intensity discharge lamp electrodes operating in hot-spot mode is presented. In this case the electrode life-time is drastically reduced by the barium layer consumption and consequently by the local temperature increase and tungsten erosion..

Keywords

Barium doped tungsten, Thin layer, Work function reduction, Diffuse and hot-spot mode functioning.

Submitted at: March 25, 2003
Accepted at: May 8, 2003

Citation

M. Cristea, G. Zissis, THIN BARIUM LAYER FORMATION AND ITS INFLUENCE ON TUNGSTEN ELECTRODE ARC ATTACHMENT MODES IN HID LAMPS, Journal of Optoelectronics and Advanced Materials Vol. 5, Iss. 2, pp. 511-520 (2003)