Direct-current high voltage discharge bulb for vehicle lamp

摘要

A direct-current high-voltage discharge bulb includes a ceramic arc tube body having a discharge emission chamber at a middle portion in a longitudinal direction thereof, a light-emitting substance which is sealed inside the discharge emission chamber together with a starting rare gas, and an anode and a cathode which are disposed so as to face each other inside the discharge emission chamber. An inside diameter of the ceramic arc tube body where the discharge emission chamber is defined is made to gradually decrease from the anode side to the cathode side.