An arc tube is provided for use in a high intensity discharge lamp. The
arc tube is generally comprised of an elongated outer envelope defining
two opposed ends and a cavity therebetween; an electrode sleeve
protruding outwardly from each end of the outer envelope, such that each
electrode sleeve has a passageway; and an electrical feedthrough member
inserted into the passageway of the electrode sleeve, where the
feedthrough member includes an inner rod that extends into the cavity of
the arc tube and a ceramic sleeve encircling a portion of the inner rod
disposed within the passageway. A sealing compound is disposed at an
outwardly facing end of the passageway for sealing the feedthrough member
to the electrode sleeve, such that the sealing compound extends into the
passageway of the electrode sleeve but is spatially separated from the
ceramic sleeve.