Femtosecond TALIF for H density measurement in RAID
POSTER
Abstract
The role of atomic hydrogen (H) is key to the dynamics of the plasma edge in tokamaks. Measurements of H density in tokamaks are nevertheless mostly indirect, often relying on analyses of optical emission spectroscopy data.
Two-photon-absorption laser-induced fluorescence (TALIF) is an absolutely-calibrated alternative, potentially providing direct and localized measurements of H density [1, 2]. In addition, femtosecond laser pulses (of spectral width ~0.1-1 nm) allow the excitation of H ground-state population independent of any broadening mechanism, opening the way to single-laser-pulse measurements of H density, that may be well adapted to tokamak operations [3].
In this work, we present the development of a single-pulse fs-TALIF system [4] in the linear device RAID [5], in a hydrogen plasma with plasma density ~1018 m-3. As part of the development of our fs-TALIF system, measurements of the fluorescence decaytime in RAID are also presented.
[1] L. Kadi et al., Plasma Phys. Control. Fusion 66, 125007 (2024)
[2] R. M. Magee et al., Rev. Sci. Instrum. 83, 10D701 (2012)
[3] A. Dogariu et al., Rev. Sci. Instrum. 93, 093519 (2022)
[4] EUROfusion Enabling Research project ENR-TEC.02.EPFL
[5] R. Jacquier et al., Fusion Eng. Des. 192, 113614 (2023)
Two-photon-absorption laser-induced fluorescence (TALIF) is an absolutely-calibrated alternative, potentially providing direct and localized measurements of H density [1, 2]. In addition, femtosecond laser pulses (of spectral width ~0.1-1 nm) allow the excitation of H ground-state population independent of any broadening mechanism, opening the way to single-laser-pulse measurements of H density, that may be well adapted to tokamak operations [3].
In this work, we present the development of a single-pulse fs-TALIF system [4] in the linear device RAID [5], in a hydrogen plasma with plasma density ~1018 m-3. As part of the development of our fs-TALIF system, measurements of the fluorescence decaytime in RAID are also presented.
[1] L. Kadi et al., Plasma Phys. Control. Fusion 66, 125007 (2024)
[2] R. M. Magee et al., Rev. Sci. Instrum. 83, 10D701 (2012)
[3] A. Dogariu et al., Rev. Sci. Instrum. 93, 093519 (2022)
[4] EUROfusion Enabling Research project ENR-TEC.02.EPFL
[5] R. Jacquier et al., Fusion Eng. Des. 192, 113614 (2023)
*This work has been carried out within the framework of the EUROfusion Consortium, via the Euratom Research and Training Programme (Grant Agreement No 101052200 —EUROfusion) and funded by the Swiss State Secretariat for Education, Research and Innovation (SERI). Views and opinions expressed are however those of the author(s) only anddo not necessarily reflect those of the European Union, the European Commission, or SERI. Neither the European Union nor the European Commission nor SERI can be held responsiblefor them.
Presenters
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Simon Vincent
- EPFL, Swiss Plasma Center (SPC), CH-1015 Lausanne