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Long-term life testing of Geostationary Operational Environmental Satellite (GOES) encoder lampsThe aging characteristics and lifetimes of tungsten filament encoder lamps were determined as a function of operating voltage and filament material. For pure tungsten and thoria doped (1 pct.) filament lamps, crystal grain growth over the center portion of the filament leads to the ultimate failure of the lamp. The development of notches associated with this grain growth is the cause of lamp burn out. Eventually, one of the notches will 'etch' through the filament, causing it to fail open. For rhenium doped (3 pct.) filament lamps, distortion of the filament leads to the ultimate failure of the lamp. The lifetime of these lamps is about 1 year at an operating voltage of 5.0 volts. The pure tungsten filament lamps have the longest average lifetime, and the thoria doped filament lamps have the shortest at 5.0 volts. The lifetimes of these lamps is about 7 years at an operating voltage of 3.5 volts. Data suggest that the rhenium doped lamps will have the longest average lifetime at 3.5 volts, and the thoria doped will have the shortest. These lifetimes are comparable to the desired lifetimes of 7 years.
Document ID
19920010821
Acquisition Source
Legacy CDMS
Document Type
Other - NASA Reference Publication (RP)
Authors
Powers, Charles E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1992
Subject Category
Metallic Materials
Report/Patent Number
REPT-92B00013
NAS 1.61:1273
NASA-RP-1273
Accession Number
92N20063
Funding Number(s)
PROJECT: RTOP 030-09-01-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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