Design and implementation of a prototype infrared video bolometer (IRVB) in MAST Upgrade

TY - JOUR

T1 - Design and implementation of a prototype infrared video bolometer (IRVB) in MAST Upgrade

AU - Federici, Fabio

AU - Reinke, Matthew L.

AU - Lipschultz, Bruce

AU - Thornton, Andrew J.

AU - Harrison, James R.

AU - Lovell, Jack J.

AU - Bernert, Matthias

N1 - Funding Information: This work was supported by U.S. Department of Energy Award Nos. DE-AC05-00OR22725 and DESC0014264 and under the auspices of the Engineering and Physical Sciences Research Council (Grant Nos. EP/L01663X/1 and EP/W006839/1). To obtain further information on the data and models underlying this paper, please contact [email protected] . Funding Information: This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Program (Grant Agreement No. 101052200-EUROfusion). The views and opinions expressed are, however, those of the author(s) alone and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. Publisher Copyright: © 2023 Author(s).

PY - 2023/3/1

Y1 - 2023/3/1

N2 - A prototype infrared video bolometer (IRVB) was successfully deployed in the Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade or MAST-U), the first deployment of such a diagnostic in a spherical tokamak. The IRVB was designed to study the radiation around the lower x-point, another first in tokamaks, and has the potential to estimate emissivity profiles with spatial resolution beyond what is achievable with resistive bolometry. The system was fully characterized prior to installation on MAST-U, and the results are summarized here. After installation, it was verified that the actual measurement geometry in the tokamak qualitatively matches the design; this is a particularly difficult process for bolometers and was done using specific features of the plasma itself. The installed IRVB measurements are consistent both with observations from other diagnostics, including magnetic reconstruction, visible light cameras, and resistive bolometry, as well as with the IRVB-designed view. Early results show that with conventional divertor geometry and only intrinsic impurities (for example, C and He), the progression of radiative detachment follows a similar path to that observed for large aspect ratio tokamaks: The peak of the radiation moves along the separatrix from the targets to the x-point and high-field side midplane with a toroidally symmetric structure that can eventually lead to strong effects on the core plasma inside the separatrix.

AB - A prototype infrared video bolometer (IRVB) was successfully deployed in the Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade or MAST-U), the first deployment of such a diagnostic in a spherical tokamak. The IRVB was designed to study the radiation around the lower x-point, another first in tokamaks, and has the potential to estimate emissivity profiles with spatial resolution beyond what is achievable with resistive bolometry. The system was fully characterized prior to installation on MAST-U, and the results are summarized here. After installation, it was verified that the actual measurement geometry in the tokamak qualitatively matches the design; this is a particularly difficult process for bolometers and was done using specific features of the plasma itself. The installed IRVB measurements are consistent both with observations from other diagnostics, including magnetic reconstruction, visible light cameras, and resistive bolometry, as well as with the IRVB-designed view. Early results show that with conventional divertor geometry and only intrinsic impurities (for example, C and He), the progression of radiative detachment follows a similar path to that observed for large aspect ratio tokamaks: The peak of the radiation moves along the separatrix from the targets to the x-point and high-field side midplane with a toroidally symmetric structure that can eventually lead to strong effects on the core plasma inside the separatrix.

UR - http://www.scopus.com/inward/record.url?scp=85149281360&partnerID=8YFLogxK

U2 - 10.1063/5.0128768

DO - 10.1063/5.0128768

M3 - Article

AN - SCOPUS:85149281360

SN - 0034-6748

VL - 94

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

IS - 3

M1 - 033502

ER -