Preliminary results of the investigation of a 3500 K black body

A new ultra-high-temperature black body designed and constructed at the All -Russian Research Institute for Optophysical Measurements (VNIIOFI, Russian Federation) has recently been delivered to the National Physical Laborator y (NPL, UK). The black-body cavity consists of a series of pyrolytic graphi te rings and is designed to operate at temperatures of up to 3500 K. Prelim inary results show that the cavity uniformity varies with operating tempera ture and change in shape of cavity bottom. Results of active and passive te mperature control art: also given.