Influence of pressure on performances of mercury free signs excited with a pulsed power supply

Summary form only given. The European standard 2002/96/CE imposes to remove mercury from discharge lamps, which include signs for public lighting. A possible alternative is to use a binary mixture of neon and xenon, excited with a pulsed power supply. In this work, the influence of mixture pressure on lighting performances is studied. An adapted sign is continuously flushed so that pressure and proportion of gases can be adjusted. The temporal evolution of 147 nm resonant line of xenon was recorded with a fast photomultiplier tube for different mixture pressures. In the normal range of operation, the results show that afterglow VUV emission increases together with mixture pressure. If VUV power is compared to visible light emitted by phosphors, it appears that illuminance follows variations of afterglow VUV emission essentially. Illuminance and afterglow VUV emission are both maximum for a pressure higher than usual pressure of signs containing mercury. Glow VUV emission never contributes for more than 50% to the 147 nm resonant line emission and has a lower influence on illuminance. Moreover, for pressures of interest, afterglow VUV emission and illuminance are the most intense for a specific proportion of xenon, which is quite low. In addition, the second molecular continuum of xenon has been recorded from 148 nm to 205 nm. It appears that this continuum emission increases with pressure, but also with xenon proportion, and so contributes to the excitation of phosphors. So, medium pressure mixtures with little proportions of xenon appear as an interesting orientation for the development of efficient pulsed powered mercury free signs