<B>Д 64.051.12 (Фізико-математичні науки) </B>
Постійне посилання колекціїhttps://ekhnuir.karazin.ua/handle/123456789/10745
01.04.08 — фізика плазми;
01.04.16 — фізика ядра, елементарних частинок і високих енергій
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Документ Поширення альфвенових хвиль та перенесення енергії поперек магнітних поверхонь у тороїдальній плазмі(Харків: Харківський національний університет імені В.Н. Каразіна, 2021) Тищенко, Маргарита Германівна; Tyshchenko, M.H.Tyshchenko M.H. Propagation of Alfvén waves and energy transfer across magnetic surfaces in toroidal plasmas. – Manuscript. Thesis for the Candidate of Science (Doctor of Philosophy) degree in Physics and Mathematics, speciality 01.04.08 – Plasma Physics. – Institute for Nuclear Research, National Academy of Science of Ukraine; V. N. Karazin Kharkiv National University, the Ministry of Education and Science of Ukraine, – Kharkiv, 2021. This dissertation is devoted to current problems of the physics of magnetohydrodynamic waves in toroidal fusion devices. It presents results of theoretical investigation of physics of the transverse energy transfer by Alfvén waves and magnetic islands, and of effects of the spatial chanelling of the energy of energetic ions/alpha particles by destabilized Alfvén eigenmodes in tokamaks. The developed theory is applied to experimental data from the spherical torus NSTX (USA) and tokamak JET (United Kingdom). It is demonstrated that toroidicity (as well as ellipticity and other kinds of deviations of the magnetic configuration from the cylindrical geometry) can result in linear transformations of propagating kinetic Alfvén waves (KAWs) into other KAW branches, which differ by their mode numbers from the initial waves. Analytical expressions for the amplitudes of the transformed and non-transformed waves are derived. The transformation is found to be strong for kinetic Alfvén waves with low poloidal mode numbers in typical tokamaks, NSTX and ITER (France). It may affect the mode numbers observed by external magnetic measurements and weaken the Landau damping of the waves, thus extending the region of the wave propagation. The latter can be important when the wave affects the plasma energy balance transferring the energy or modifying the plasma transport coefficients.Документ Хвильові процеси та транспорт надтеплових іонів у квазиізодинамічних стелараторах(Харків: ХНУ імені В. Н. Каразіна, 2019) Тихий, А.В.; Tykhyy, A.V.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.