| 摘要 |
In a high intensity metal halide discharge lamp utilizing thorium in conjunction with a transport cycle for electrode activation, a getter, preferably cadmium or zinc is added to the lamp fill for the purpose of reducing the concentration of free iodine during operation. By so doing, deposition of thorium on the electrode tip during operation is assured and performance and maintenance are improved. The quantity of getter may include a portion supplied as a corrective measure to scavenge excess iodine released during manufacture, and another portion providing a long-term buffering capacity for capturing iodine released during the lamp's life by reaction of the dose, particularly ScI3 and ThI4, with the SiO2 of the lamp envelope. |
