High Pressure Sodium Vapour Lamps with a polycrystalline translucent aluminum oxide discharge tube enclosed in an ovoid or tubular outer glass envelope. The avoid shell of the SON-LAMPS is internally coated with aluminum oxide powder. The discharge tube contains an amalgam of mercury and sodium along with xenon gas. The outer shell is evacuated and a better maintains this high degree of vacuum throughout the lamp life. These lamps need a control gear comprising of Ballast, Ignitor and capacitor for optimum performance.