Metal vapor discharge lamp

摘要

A metal vapor discharge lamp includes a discharge tube (1) comprising a translucent ceramic discharge portion (7) that defines a discharge space in which a luminous metal is sealed, slender tube portions (82,85) provided on both ends of the discharge portion (7), a pair of electrodes provided with coils (102,105) at the tips thereof, electrode supports (112,115) that support the electrodes at one end thereof and extend all the way to the ends of the slender tube portions (82,85) on the side opposite to the discharge space at the other end thereof, and a sealant (122,125) for sealing the ends of the slender tube portions (82,85) on the side opposite to the discharge space so as to attach the electrode supports (112,115) to the inner surfaces of the slender tube portions (82,85), in which X > 0.0056P + 0.394 is satisfied, where P is a lamp power (W) and X is a distance (mm) from the ends of the coils (102,105) on the side of the slender tube portions (82,85) to the ends of the slender tube portions (82,85) on the side of the discharge space. <IMAGE>