18th Technical Meeting on Energetic Particles in Magnetic Confinement Systems

Energy fluxes and their effects on eigenmodes during spatial channeling

Not scheduled

20m

Collective Phenomena

Speaker

Dr Yurii V. Yakovenko (Institute for Nuclear Research, Kyiv, Ukraine)

Description

Spatial channeling – the fast-ion energy and momentum transfer across the magnetic field by destabilized modes – affects plasma performance, deteriorating or improving it [1-3]. It manifests itself, in particular, by twisting the mode radial structure, which was observed in experiments on tokamaks, see [4,5] and references therein. In this work, it is revealed that there is a correlation between the direction of the radial wave-energy flux, the orientation of the mode twist, and the direction of mode rotation. The mode twist parameter is introduced, and relations connecting it with the energy flux are established. It is shown that the energy flux transforms zeros of the radial profile of the mode amplitude into minima (i.e., zeros disappear). Twist is the largest at the radii where the mode amplitude is small. These findings can be used for diagnostics of the energy fluxes generated by fast-ion driven instabilities.

Specific calculations are carried out for fast magnetoacoustic modes (FMM) and Alfvén eigenmodes (AE) – GAE, RSAE, and TAE modes. A particular analysis is carried out for a DIII-D experiment where RSAE modes were observed. Peculiarities of various modes, in particular, of those observed experimentally in the DIII-D and NSTX tokamaks, are discussed. These results are partly published in Ref. [6].

[1] Ya. I. Kolesnichenko, Yu. V. Yakovenko, and V.V. Lutsenko, Phys. Rev. Lett. 104, 075001 (2010).
[2] E.V. Belova et al., Phys. Plasmas 24, 042505 (2017).
[3] Ya.I. Kolesnichenko, A.V. Tykhyy, and R.B. White, Nucl. Fusion 60, 112006 (2020).
[4] B.J. Tobias et al., Phys. Rev. Lett. 106, 075003 (2011).
[5] W.W. Heidbrink, E.C. Hansen, M.E. Austin, G.J. Kramer, and M.A. Van Zeeland, Nucl. Fusion 62, 066020 (2022).
[6] Ya.I. Kolesnichenko, V.V. Lutsenko, A.V. Tykhyy, Yu.V. Yakovenko, and W.W. Heidbrink, Phys. Plasmas 31, 112509 (2024).

Work was supported by Subaward #2022-1701 of the US DoE Grant DE-FG02-06ER54867 via STCU Project P786/UCI and by the US DoE Grant No. DE-SC0020337.