Prototype Design of a 700 °C In-Vacuum Blackbody Source for In Situ Calibration of the ITER ECE Diagnostic

Two blackbody sources permanently located within the international thermonuclear experimental reactor (ITER) diagnostic shield module at equatorial port 9 will operate in conjunction with two remotely retractable mirrors to generate and direct blackbody radiation to calibrate the radial and oblique views of the ITER electron cyclotron emission diagnostic. The main calibration requirements include a high-emissivity surface heated to 700 °C or higher, the ability to perform the calibration in high vacuum and in the presence of a magnetic field, and 5000-h operational lifetime over 20 years. Major constraints include a heater current limit of 40 A, no direct fluid cooling to mitigate failure risks, small size to avoid compromising neutron shielding, and adequate structural support to mitigate vibration loads. This paper describes the preliminary design of a hot calibration source supported by analysis and test results of a calibration source test prototype developed to address the calibration source requirements and its constraints.