| 摘要 |
An hermetically sealed arc tube 14 has a longitudinal axis 60 and contains therewithin an arc generating and sustaining medium, as is known. The ends of th e arc tube 14 are sealed with press-seals 43. The seals comprise a substantially parallelepipodonal structure having oppositely disposed, planar sides 56 and 58. A molybdenum foil 50 is sealed in each of the press-seals and is substantially cen trally located between the planar sides 56 and 58. An in-lead 52 is secured as by weldi ng to an end of foil 50 and extends outwardly of the arc tube for electrical connectio n to a source and an electrode 46 is attached to the other end of foil 50 and projects into the arc chamber. A first rod-relief member 62 in the form of a projecting boss 64 is formed on one of the planar sides, for example, 58, and a second rod-relief memb er 66 in the form of a depression 68 is formed on the other of the planar sides, in th is instance side 56. The rod-relief members cooperate to center the electrode on th e longitudinal axis within a variance of < 1.degree..
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