Information is needed about Tungsten Halogen Lamps. Key questions such as operating temperature required and the length of operational time required to keep the envelope clean. If lamps are activated for just short periods of time how long at operating temperature is required to clean envelope and deposit tungsten back on the filament?

 

Try a Google search on the exact phrase: "halogen cycle."

Browsing the first page of hits suggests operating temp of 200-250C. I'd guess it varies by manufacturer.