Patent ID: 8120256

Claim:
A direct current discharge lamp with an anode and a cathode that are arranged opposite one another at a predetermined distance inside a discharge vessel filled with a filling gas, wherein at least the predetermined distance between the anode and the cathode, electric power applied to the anode and the cathode to produce a gas discharge, and a geometry of the anode are selected such that a region of a surface of the anode facing the cathode is free flowing in the heated state of the direct current discharge lamp, wherein starting from the surface facing the cathode, the anode has a length of at least 5 mm, and wherein a quotient Q of the electric power in W and the distance between the anode and the cathode in mm is defined in at least the heated state of the direct current discharge lamp by the relationship b 1 *A 2 +b 2 *A+b 3 <Q<a 1 *A 2 +a 2 *A+a 3 , where: a 1 =−0.0001 W*mm −7 ; a 2 =0.42 W*mm −4 ; a 3 =687 W*mm −1 ; b 1 =−0.0003 W*mm −7 , b 2 =0.8967 W*mm −4 ; and b 3 =88 W*mm −1 , A denoting the volume of the anode in mm 3 on the first 5 mm length starting from the surface facing the cathode.