Time-dependent behavior of the contraction regions of high-pressure mercury arcs

Abstract
The paper describes an investigation of the time-dependent behavior of the impedance of high-pressure mercury lamps operated with pulsed current. The lamp impedance was obtained experimentally from electric as well as spectroscopic measurements, the latter also allowing a determination of axial impedance profiles. These measurements show that during current-off the most significant part of the lamp impedance is located close to the electrodes, whereas during current-on a more homogeneous impedance profile is observed. The arc channel close to the electrodes is found to be rather narrow and therefore its high impedance during current-off can be reduced significantly by an additional current which is small compared to the average lamp current.