Development, calibration and performance testing of the infrared imaging video bolometer for the SST-1 Tokamak

Infrared Imaging Video Bolometer (IRVB) is a powerful diagnostic tool for the measurement of total radiated power losses from the plasma device and it can provide temporally resolved two-dimensional (20) images of plasma radiation brightness. Recently IRVB system is designed, developed, calibrated, tested for its performance and installed on the ADITYA Tokamak for initial studies. IRVB is being developed for the first phase of SST-1 tokamak and is to be deployed at mid plane of radial port 2 with tangential viewing geometry. The IRYB developed for the SST-1 tokamak utilizes a 2.5 μm thick and 9 x 7 cm² size free standing Platinum foil as a radiation absorber element which provides broad radiation absorptions band 1 eV to 8.5 keV (Soft X-Ray to IR). The foil is clamped on a metal frame. A pinhole camera geometry with square aperture of 0.7 x 0.7 provides 13 x 10 bolometer pixels 2-D array (130 channels) and ∼8 em of spatial resolution at the plasma mid plane with a 61° x 48° wide field of view (FOY). This wide FOY covers a tangential and a poloidal cross sectional views of SST-1 plasma. The FOY provides unique plasma viewing geometry which is confirmed by the synthetic diagnostic model results. A medium wave Infrared Camera having 320 x 240 focal plane arrays, 142 Hz full frame rate and temperature sensitivity ∼ 0.02℃ is used to record 2-D temperature distribution of the foil. Using 2-D heat diffusion analysis method, total radiated power can be estimated. The Noise Equivalent Power Density of the IRYB system has been found to be ∼ 200 μW/cm². The present paper discusses the development and calibration of the SST-1 IRYB system. Performance of the IRVB system for its time response and NEP are experimentally investigated and has also been reported here. (author)