Poloidal trapping of the high-frequency Alfvén continuum and eigenmodes in stellarators

Yakovenko, Yu. V.; Weller, A.; Werner, A.; Zegenhagen, S.; Fesenyuk, O. P.; Kolesnichenko, Ya. I.

doi:10.1088/0741-3335/49/4/015

Cited by 13 publications

(3 citation statements)

References 35 publications

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“…Different field lines would correspond to different coefficients in this equation, which is indicative of the localization of the mode in real space. As in the theory of ideal ballooning modes, high nTAEs have been successfully studied in stellarators [299,300] with the use of this formalism. We review the properties of AEs specifically for 3D geometries.…”

Section: Characteristic Aes In 3d Plasmasmentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

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The area of energetic particle (EP) physics in fusion research has been actively and extensively researched in recent decades. The progress achieved in advancing and understanding EP physics has been substantial since the last comprehensive review on this topic by Heidbrink and Sadler (1994 Nucl. Fusion 34 535). That review coincided with the start of deuterium-tritium (DT) experiments on the Tokamak Fusion Test Reactor (TFTR) and full scale fusion alphas physics studies. Fusion research in recent years has been influenced by EP physics in many ways including the limitations imposed by the 'sea' of Alfvén eigenmodes (AEs), in particular by the toroidicity-induced AE (TAE) modes and reversed shear AEs (RSAEs). In the present paper we attempt a broad review of the progress that has been made in EP physics in tokamaks and spherical tori since the first DT experiments on TFTR and JET (Joint European Torus), including stellarator/helical devices. Introductory discussions on the basic ingredients of EP physics, i.e., particle orbits in STs, fundamental diagnostic techniques of EPs and instabilities, wave particle resonances and others, are given to help understanding of the advanced topics of EP physics. At the end we cover important and interesting physics issues related to the burning plasma experiments such as ITER (International Thermonuclear Experimental Reactor).

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Section: Characteristic Aes In 3d Plasmasmentioning

confidence: 99%

Energetic particle physics in fusion research in preparation for burning plasma experiments

2014

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“…This is an HAE (helical Alfvén eigenmode) with strong poloidal and toroidal couplings. The continuum plot given on the left also shows evidence of continuum-crossing gap structures [17], which are often present in the continua of three-dimensional systems. 4 Stability analysis using a wave-particle energy transfer method…”

Section: Alfvén Eigenmodes In Stellaratorsmentioning

confidence: 83%

Energetic‐Particle‐Driven Instabilities in General Toroidal Configurations

Spong¹,

Breǐzman

Brower

et al. 2010

Contrib. Plasma Phys.

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Energetic-particle driven instabilities have been extensively observed in both tokamaks and stellarators. In order for such devices to ultimately succeed as D-T fusion reactors, the super-Alfvénic 3.5 Mev fusion-produced alpha particles must be sufficiently well confined. This requires the evaluation of losses from classical collisional transport processes as well as from energetic particle-driven instabilities. An important group of instabilities in this context are the discrete shear Alfvén modes, which can readily be destabilized by energetic particles (with velocities of the order of v Alfvén ) through wave-particle resonances. While these modes in three-dimensional systems have many similarities to those in tokamaks, the detailed implementation of modeling tools has required development of new methods. Recent efforts in this direction will be described here, with an emphasis on reduced models.

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“…Between the (6, 0) and (2, −1) gap, the (2M, 0) gap family and the (2M, −1) gap family clash and cross each other, creating very complicated patterns. The clash leads to a reduction of the gap width or even a complete elimination of one or both gaps at the crossing site [42].…”

Section: Inside the Island Chainmentioning

confidence: 99%

The shear Alfvén continuum with a magnetic island chain in tokamak plasmas

Qu¹,

Hole²

2022

Plasma Phys. Control. Fusion

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The shear Alfv én continuum spectrum is studied for a tokamak with a single island chain using the ideal Magnetohydrodynamics (MHD) theory. We have taken into account the toroidal geometry and toroidal mode coupling with the island considered as a highly-shaped stellarator. Various new frequency gaps open up inside the island due to its asymmetry both poloidally and toroidally, such as the Mirror-induced Alfv én Eigenmode (MAE) gap and the Helicity-induced Alfv én Eigenmode (HAE) gap. We have shown that the MAE gap acts as the continuation of the outside Toroidal Alfv én Eigenmode (TAE) gap into the island. However, the combined TAE/MAE gap is getting narrower as the island grows, leaving only half of its original width with a moderate island size as much as 3.2% of the minor radius. In addition, the two-dimensional eigenfunction of the continuum mode on the lower tip of the MAE gap now has highly localised structures around the island's long axis, contrary to the usual oscillatory global solutions found with no or a low level of toroidal asymmetry - an indication of the continuous spectrum becoming discrete and dense. These results have implications for the frequency, mode structure and continuum damping of global TAEs residing in the gap.

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Poloidal trapping of the high-frequency Alfvén continuum and eigenmodes in stellarators

Cited by 13 publications

References 35 publications

Energetic particle physics in fusion research in preparation for burning plasma experiments

Energetic particle physics in fusion research in preparation for burning plasma experiments

Energetic‐Particle‐Driven Instabilities in General Toroidal Configurations

The shear Alfvén continuum with a magnetic island chain in tokamak plasmas

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