ABSTRACT
INTRODUCTION At hot tungsten cathodes of high intensity discharges different modes of current transfer can be found: a diffuse mode characterized by a low current density and a high global electrode temperature with a uniform distribution, and a spot mode, characterized by a spot with a high current density and a high surface temperature. For the DC case an investigation on these different modes is presented in two accompanying papers [1, 2]. These different modes of arc attachment also occur in AC operation [3]. In this paper experimental investigations at the Bochum model lamp concerning the different modes of arc attachment in AC operation are presented.
