A High Pressure Mercury Vapour Discharge Lamp

The mercury is vaporised inside the quartz capsule by a small low current arc from the auxiliary electrode. After about 5 minutes there is sufficient mercury vapour in the capsule to start the arc between the main electrodes. The lamp should be left a further 10 minutes to allow the lamp to stabilise & for it to attain full working intensity. As to BS EN ISO 3059 minimum warm up period of 10 minutes for the lamp.

The spectrum of electromagnetic radiation produced extends into the ultraviolet range.