Experimental observations of fast-ion losses induced by neoclassical tearing modes in the MAST-U spherical tokamak
Neoclassical tearing modes (NTMs) have been identified as the most deleterious perturbations in high-performance plasmas at Mega Amp Spherical Tokamak Upgrade (MAST-U). They produce magnetic islands that flatten the electron temperature profile and enhance the fast-ion transport. Understanding the N...
| Autores: | , , , , , , , , |
|---|---|
| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Recursos: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/176326 |
| Acesso em linha: | https://hdl.handle.net/11441/176326 https://doi.org/10.1088/1361-6587/adc3be |
| Access Level: | acceso abierto |
| Palavra-chave: | Fast particles Fast-ion diagnostics Fast-ion losses Neoclassical tearing modes Spherical tokamak Magnetic confined fusion |
| Resumo: | Neoclassical tearing modes (NTMs) have been identified as the most deleterious perturbations in high-performance plasmas at Mega Amp Spherical Tokamak Upgrade (MAST-U). They produce magnetic islands that flatten the electron temperature profile and enhance the fast-ion transport. Understanding the NTM-induced losses can reveal paths to mitigate them, thus increasing the energy available to heat up the plasma. The MAST-U fast-ion loss detector (FILD) is equipped with a high-resolution camera and a high-speed camera that simultaneously measure the fast-ion losses in MAST-U. The combination of both systems makes it possible to infer the velocity-space of the losses fluctuating at the frequency of the NTMs. The FILDSIM code is used to infer the velocity space of the fast-ion losses from the strike position in a scintillator plate. Eulerian video magnification is employed to identify the losses that oscillate at the frequencies of the NTMs. NTMs produce fast-ion losses across a broad range of velocity space, with pitch angles ranging from 35∘ to 54∘. Non-linear interactions between the fast-ion orbits and different magnetic islands have been observed. The lost fast-ion orbits meet the stringent conditions that makes it possible to measure these effects. |
|---|