Patent ID: 6369508
Filing Date: 2002-04-09
Classification: G03F,H01J

Abstract:
Mercury short-arc lamp havinga discharge vessel (1) which surrounds an ionizable filling, two electrodes which are arranged opposite one another inside the discharge vessel (1), each electrode comprising an electrode head (2, 3) and an electrode rod (4) defining a longitudinal axis (L), which electrode rod (4) supports the electrode head (2, 3), a getter (7; 12) which is arranged on an electrode rod (4), characterized in that the getter (7; 13) consists of niobium, and the two following conditions are fulfilled: D>1.8Â·d and&agr;&gE;20Â°, D and d respectively denoting a diameter of the relevant electrode head (2) and the associated electrode rod (4), and &agr; denoting an angle whichâ€”viewed in a plane containing the electrode longitudinal axis (L)â€”is defined by the electrode longitudinal axis (L), on the one hand, and an imaginary connecting line (8), on the other hand, the connecting line (8) connecting a point (P2) on an imaginary perpendicular (11), running through the end of the electrode rod on the electrode head side, to the end (P1) of the getter (7; 12) averted from the electrode head, and the point (P2) corresponding to a projection of the maximum radius (r) of the lateral surface (11) of the electrode head (2) onto this perpendicular (11).