Measurement of a 2D fast-ion velocity distribution function by tomographic inversion of fast-ion D-alpha spectra
We present the first measurement of a local fast-ion 2D velocity distribution function f (v , v⊥). To this end, we heated a plasma in ASDEX Upgrade by neutral beam injection and measured spectra of fast-ion Dα (FIDA) light from the plasma centre in three views simultaneously. The measured spectra ag...
| Autores: | , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | España |
| Recursos: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/100542 |
| Acesso em linha: | https://hdl.handle.net/11441/100542 https://doi.org/10.1088/0029-5515/54/2/023005 |
| Access Level: | acceso abierto |
| Palavra-chave: | Fast-ion velocity distribution function Tomography Inverse problems Fast ions in tokamaks |
| Resumo: | We present the first measurement of a local fast-ion 2D velocity distribution function f (v , v⊥). To this end, we heated a plasma in ASDEX Upgrade by neutral beam injection and measured spectra of fast-ion Dα (FIDA) light from the plasma centre in three views simultaneously. The measured spectra agree very well with synthetic spectra calculated from a TRANSP/NUBEAM simulation. Based on the measured FIDA spectra alone, we infer f (v , v⊥) by tomographic inversion. Salient features of our measurement of f (v , v⊥) agree reasonably well with the simulation: the measured as well as the simulated f (v , v⊥) are lopsided towards negative velocities parallel to the magnetic field, and they have similar shapes. Further, the peaks in the simulation of f (v , v⊥) at full and half injection energies of the neutral beam also appear in the measurement at similar velocity-space locations. We expect that we can measure spectra in up to seven views simultaneously in the next ASDEX Upgrade campaign which would further improve measurements of f (v , v⊥) by tomographic inversion. |
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