Conceptual design for resistive bolometer system with multiple apertures for measurement of total radiated power in JT-60SA

A field of view (FoV) of the resistive bolometer systems specialized for the total radiated power analysis has been designed with bolometer systems having multiple-apertures in JT-60SA. The multi-aperture bolometer system can reduce the required number of bolometer channels for the determination of the total radiated power. The FoV design has been carried out to minimize unobserved and overlapping regions with the following requirements: (i) independent determination of the divertor and the main plasma radiation, (ii) limitation of the use of only three diagnostic ports, and (iii) a redundant FoV design. With the designed FoV, the whole plasma of JT-60SA is viewed by only five bolometers and five replicated bolometers having the same FoV for redundancy. A signal evaluation with the designed FoV with a predetermined radiation profile indicates that even the lowest performing bolometer exhibits a signal to noise (S/N) ratio of 300 or more. The evaluated S/N ratio is high enough for the total radiated power analysis. Using the designed FoV, the total radiated power over the plasma profile can be determined within 5.3% using only five bolometers.