Agoston Boroczki

Investigation of feasibility and improvement of the destructive in situ lamp impurity tester

In order to perform gas impurity analysis on operating lamps, a mass spectrometer based in situ fracture stage has been built (Boroczki et al 2006 Meas. Sci. Technol. 17 79). The main problem of the elevated temperature measurements is the rapid condensation of the constituents after fracturing the lamp. There are two available options to record more spectra before the thermal equilibrium is reached. The first option is to increase the speed of the recording, but this is limited by the QMS unit. The second option is to introduce a buffer gas before fracturing, which slows down the diffusion process and thus increases the diffusion time (i.e. elapsed average time between the fracturing of the lamp and the impact of the particles with the wall) because the mercury atoms cannot travel in a straight line to the wall but rather suffer multiple collisions with the atoms of the buffer gas. In the present paper the authors investigated the second option by developing an improved measuring system. The speed of the recording can be investigated through the condensation phenomenon after fracturing the lamp. In order to observe the condensation phenomenon, the partial pressure of the mercury additive at different background pressures in the fracture chamber has been studied. The results of these measurements are reported in the present paper.