An Iodine Incandescent Lamp with Virtually 100 Percent Lumen Maintenance

This paper will describe the theory and operation of a new type of incandescent lamp which employs iodine in a regenerative process in which evaporated tungsten is redeposited on the filament, resulting in approximately 100 percent lumen maintenance and increased life. While the concept of using a halogen such as chlorine, bromine, or iodine in a lamp to prevent blackening is not novel, the difficulties associated with the regenerative process have previously precluded its practice. For the first time these difficulties have been overcome and a practical lamp employing iodine in a regenerative cycle can be produced.