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DIFFER Publication

Maximizing the ion temperature in an electron heated plasma: from WEST towards larger devices

Author
Abstract

In electron heated plasmas, as the power increases, it is experimentally reported that the ion temperature (Ti) saturates while the electron temperature (Te) increases [Beurskens NF 2022]. As on AUG, W7X and elsewhere, Ti saturates around 1.5 keV in WEST L-mode electron heated plasmas while Te reaches 4 keV. Simulations within the integrated model METIS have been compared against a whole WEST campaign consisting mostly of L-mode plasmas with Lower Hybrid heating ranging from 1 to 5.5 MW. In METIS, the collisional equipartition is modelled as well as the turbulent heat transport using the neural network regression of the quasilinear gyrokinetic code QuaLiKiz. The observed Ti saturation is well captured by the modelling framework. The saturation correlates with a low ratio of the energy confinement time to the volume averaged electron-ion collisional heat exchange time. It is then shown that Ti saturation in electron heated plasma is due to an equipartition lower than the energy confinement time. In larger devices, no Ti saturation is expected nor predicted by physics based integrated modelling used in this work, thanks to equipartition times sufficiently shorter than the energy confinement time.

Year of Publication
2024
Journal
Nuclear Fusion
Volume
64
Issue
3
Number of Pages
036011
DOI
10.1088/1741-4326/ad171e
PId
41cf7b6c1eb8faae98d3e9fd48605ed6
Alternate Journal
Nucl. Fusion
Label
OA
Journal Article
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