https://doi.org/10.1140/epjs/s11734-025-01763-0
Regular Article
Fast-ion-driven Alfvén eigenmodes during ICRF-heated high βp plasmas on EAST
1
Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, 230031, Hefei, China
2
University of Science and Technology of China, 230026, Hefei, China
3
Institute for Fusion Studies, Department of Physics, University of Texas at Austin, 78712, Austin, TX, USA
4
Department of Physics, University of Helsinki, Helsinki, Finland
Received:
1
March
2025
Accepted:
16
June
2025
Published online:
8
July
2025
Fast-ion-driven Alfvén eigenmodes (AEs) are observed during ICRF-heated high-βp plasmas on EAST. Multiple high frequency modes are observed for shot 112670 at fTAE1 ~ 145 kHz, δB/B ~ 4 × 10–4 and fTAE2 ~ 175 kHz, δB/B ~ 1.2 × 10–5 measured by high-frequency Mirnov coils, at B0 ~ 2.45 T, Ip ~ 350kA, ne ramp-up from 3.5 × 1019 to 4 × 1019 m−3 at PECRH ~ 2 MW, PLHW ~ 2 MW, and PICRH ~ 2.1 MW. Here, 37 MHz ICRF minority hydrogen heating scheme, located at plasma core, creates fast ion population which drives TAEs unstable from TORIC + SFFPQL. In the experiment, it is observed that the evolution of mode frequency depends on electron density, following the theoretical TAE frequency characteristic 
. As the electron density increases, the amplitude of the AE mode progressively diminishes. Higher plasma density shortens the fast-ion slowing-down time, reduces the heating efficiency of minority hydrogen, weakens the high-energy tail, and consequently decreases the fast-ion beta. Based on the diagnostic results from the microwave reflectometer and electron cyclotron emission (ECE) diagnostics, the TAE is located within the plasma core, consistent with the narrower core region of the TAE gap observed in the continuous spectrum.
© The Author(s) 2025
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