A Single-Channel Metal Foil IR Bolometer for Toroidal Radiation Asymmetry Studies during Plasma Disruptions and Disruption Mitigations in Aditya-U Tokamak

A single-channel IR bolometer comprising a Platinum foil behind an aperture is developed for the first time to measure the plasma radiation power loss and to study the toroidal radiation asymmetry during plasma disruptions in the Aditya-U tokamak. An IR photo detector having a wavelength sensing range between 3-5 μm is used to detect the thermal radiation emitted by the Graphite blackened Platinum foil. The bolometer size and distances are kept considering the availability of the port and the required physics study. A model equation is derived for the temperature calibration of the IR detector, and experimental calibration data are fitted to the equation. The graphite-coated Platinum foil is calibrated to find the calibration parameters, such as the thermal properties of the foil and the cooling time constant, which will be used to retrieve the incident power. This bolometer is similar to the IR video imaging bolometer, except that a single-channel IR detector is used instead of an IR camera having a 2D pixel array. The single-channel IR bolometer measures the average temperature of a metal foil, which is used to calculate the total incident radiative power. In the Aditya-U tokamak, 5–6 such single-channel IR bolometers are being installed at different toroidal locations along the vacuum vessel to study toroidal radiation asymmetries during disruption mitigation experiments using massive gas injection (MGI), He and Ar gas puffs. The develoment and calibration of these bolometers, along with preliminary results of plasma radiation power measurements will be briefly presented in the poster.