2008 Volume 77 Issue 4 Pages 367-374
High-intensity discharge lamps (HID lamps) are required to sustain a stable high-pressure discharge over a long time. Most HID lamps use high-density, high-temperature plasmas produced by electrode phenomena. This has inhibited the further improvement of lamp properties due to problems caused by the electrodes, such as electrode evaporation and the restriction on the use of chemical additives that may improve lamp properties because of their active chemical reactions with electrodes. Antenna-excited microwave discharge (AEMD) is proposed in the present work to produce a compact high-density plasma in high-pressure gases by a high-intensity microwave electric field that accumulates in the antenna gap. AEMD is applied to a compact metal halide discharge lamp, a superhigh-pressure mercury lamp and a sulfur lamp. The metal halide discharge lamp with a spot light source showed high luminous efficacy.
