Patent ID: 8482198

Claim:
A lamp comprising: a discharge vessel; electrodes spaced apart in the discharge vessel comprising tungsten or tungsten alloy; a fill sealed with the vessel having a pressure below 80 mbar, the fill comprising: a starting gas which comprises: xenon, krypton, argon or combinations thereof with the exception of pure argon; optionally radioactive Kr85 with a maximum activity level of 0.124 MBq/l as part of the starting gas; a voltage riser component; a metal halide component; and an active tungsten regeneration cycle wherein the fill comprises a species of said tungsten or said tungsten alloy of the electrode material during lamp operation, wherein the solubility of tungsten or components of tungsten alloy in said tungsten or tungsten alloy species is lower in the gas phase adjacent to the electrodes than at close proximity of the wall of the discharge vessel.