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Information × Registration Number 2119U000913, Article popup.category Книга Title Wave processes and transport of suprathermal ions in quasiisodynamic stellarators (AI translated) popup.author Тихий А.В.Tykhyy A.V.Tykhyi A.V.Tykhyy A.V. popup.publication 01-01-2019 popup.source_user Харківський національний університет імені В. Н. Каразіна popup.source https://ekhnuir.karazin.ua/handle/123456789/14817 popup.publisher Харків: ХНУ імені В. Н. Каразіна Description Tykhyy A.V. Wave processes and transport of suprathermal ions in quasiisodynamic stellarators. – Manuscript. Thesis for the scientific degree of candidate of science in physics and mathematics by speciality 01.04.08, Plasma Physics. – Institute for Nuclear Research, National Academy of Sciences of Ukraine; V. N. Karazin Kharkiv National University, Ministry of Education and Science of Ukraine, Kharkiv, 2019. It is demonstrated for the first time that Alfvén eigenmodes can be destabilized by ion temperature gradient in non-axisymmetrical systems. From the developed theory it follows that the destabilizing influence of spatial inhomogeneity of bulk plasma with a Maxwellian velocity distribution on Alfvén eigenmodes in toroidal systems can overcome their damping via the Landau mechanism. A necessary condition of mode destabilization is derived. It is shown that the destabilizing influence grows with the increase of the resonance velocity relative to the thermal velocity, when their ratio is greater than unity, but because of the exponential decrease of the increment of the drive with the growth of this ratio, intermediate values of 2-3 are optimal for destabilization; in stellarators, resonance velocities required to provide this ratio can exist due to non-axisymmetric resonances. It is shown that this mechanism may lead to the destabilization of an Alfvén eigenmode with frequency ω ~ 200 kHz in Wendelstein 7-X through a resonance with the helical harmonic of the equilibrium magnetic field with mode numbers µ = ν = 1, accompanied by inward spatial channeling of ion energy. The destabilization of such a mode may explain long-lasting high-frequency oscillations which have been observed experimentally. popup.nrat_date 2026-04-13 Close