Arc tube for electrodeless lamp

摘要

An arc tube (18) for an electrodeless metal halide discharge lamp has an arc chamber fabricated from a material selected from the group consisting of magnesia-doped polycrystalline alumina, silicon dioxide doped polycrystalline alumina and mono-crystalline alumina. The arc chamber is tubular and has at least one end and has a given outside diameter. At least one end cap (22,22a) closes the at least one end of the arc chamber, the end cap (22,22a) being formed from magnesia-doped polycrystalline alumina and comprising a substantially cup-shaped member having an inside diameter which is sealed to the outside diameter of the arc chamber by a shrink-fit.