Abstract: To reduce the quantity of a noble gas, typically xenon, and improve the sk and vibration resistance of the quartz glass bulb upon possible movement of electrode support shafts (4, 4') in transport or handling, a support element (6, 6') is engaged against a constriction between the bulb portion (1) and the neck portions (2, 2') of the discharge vessel structure. A spiral spring (8), preferably of tungsten, is engaged against one or more ceramic, perferably aluminum oxide disks, backed up against a melt seal, and pressing the respective disk or disks against the support element. The ceramic disks are loosely seated on the electrode shaft and located within the neck portions with clearance, so that, upon operation of the lamp, and expansion due to heating of the ceramic disks, the stability of the arc is improved and ignition is facilitated due to the lower fill pressure of the noble gas.