On the interplay between turbulent forces and neoclassical particle losses in zonal flow dynamics

Gerrú, R.; Mulas, S.; Losada, U.; Castejón, F.; Liu, B.; Estrada, T.; Hidalgo, C.

doi:10.1088/1741-4326/ab34f7

Cited by 9 publications

(11 citation statements)

References 31 publications

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“…These results are consistent with recent Monte Carlo simulations showing that radial electric fields in the range of those experimentally measured have an effect in the edge neoclassical orbit losses in the TJ-II stellarator [163]. Although the order of magnitude of turbulent acceleration is comparable to the neoclassical damping of perpendicular flows, its dependence with radial electric fields is not correlated with the evolution in the amplitude of LRC.…”

Section: Influence Of Nc Viscosity and Rs On The Dynamics Of Zonal Flowssupporting

confidence: 91%

Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator

Kobayashi¹,

Losada²,

Liu³

et al. 2019

Nucl. Fusion

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y a toda la gente que me apoyó: mis amigos Eric, Patricio, Antonio González y Carlos Raúl. También Marga, Teresita, Idelsa, Isabel, etc. Gracias a Karen Velázquez por haber sido una cercana compañía en mi vida y en los momentos finales de esta tesis. Especialmente gracias una persona que es como mi hermano de sangre, Juan Carlos Arias Valdes.Pero sobre todo, gracias á miña familia, meus pais, Ramón e Pura, o meu irmau Jorge, os meus avós Manolo, Celeste, Avelino e Pura. Os meus bisavós Eudosia e José. As miñas tías Avelina, Manuela, María, meu tío Pepe e meus primos Brais e María. Meus tíos Amaro e Carmen. Gardo un espacio privilexiado para os meus amigos de sempre de Cenlle: Dani e Diego, por quenes teño un profundo amor e respecto, xa que non tuveron as mesmas oportunidades que min nin unha vida tan sinxela. Gracias a todas esas persoas que conocín xogando ó fútbol en Galicia, especialmente a Manuel Iglesias (Fleitas), así como a Marcos, Borja, Miguel Freire, Fran, Hugo García, entre outros. Gracias a Carolina Méndez, por ser unha persoa tan importante para min e por apoiarme desde o principio, habendo estado ó meu lado durante os momentos críticos.Non podo esquecerme dos meus compañeiros da Universidade de Vigo, que me acompañaron durante a Licenciatura en Física, por 5 anos. Especial recordo teño para Javi, Hugo e Miguel. Imposible sería esquecer todo o tempo que pasamos xuntos estudanto Física e apoiándonos, que acabou resultando en sendos fermosos percorridos profesionais no ámbito da física. Esta tesis tamén vai adicada a eles, así como a os meus profesores durante o pre-universitario, Margarita Aller, Alberto Viso, Jorge Casalderrei e Aurelio.Tambem para as pessoas especiais que estão agora no belo país de São Tomé e Principe.Para todos eles e outros companheiros com quem naveguei pelos mares mais bravos e dos quais extraí as mais valiosas sabedorias, este trabalho é dedicado. Moito Obrigado.

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Section: Influence Of Nc Viscosity and Rs On The Dynamics Of Zonal Flowssupporting

confidence: 91%

Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator

Kobayashi¹,

Losada²,

Liu³

et al. 2019

Nucl. Fusion

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“…The interplay between NC radial electric fields, Reynolds stress gradients and LRCs has been investigated in different plasma scenarios in TJ-II. Turbulent driven acceleration alone cannot explain the dynamics of ZFs whose radial width is affected by the isotope mass [48]. These results are in line with the expectation that the interplay between turbulent and NC mechanisms is an important ingredient of the dynamics of edge ZFs.…”

Section: Edge Zonal Flows and Radial Electric Fieldssupporting

confidence: 85%

“…The unique experimental system that is the TJ-II stellarator has made it possible to obtain direct experimental evidence of self-organization processes consistent with the concept of ZFs. Recent experiments, developed within the framework of intense international collaborations, have demonstrated the influence of plasma ECRH and NBI heating conditions [47], the entangled role between turbulence and particle orbits [48], the influence of isotopic mass [49] and proximity to operational (density) limits [50] on the properties and dynamics [51] of ZFs in the TJ-II stellarator.…”

Section: Edge Zonal Flows and Radial Electric Fieldsmentioning

confidence: 99%

Overview of the TJ-II stellarator research programme towards model validation in fusion plasmas

Hidalgo¹,

Ascasíbar²,

Alegre³

et al. 2022

Nucl. Fusion

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TJ-II stellarator results on modelling and validation of plasma flow asymmetries due to on-surface potential variations, plasma fuelling physics, Alfvén eigenmodes (AEs) control and stability, the interplay between turbulence and neoclassical (NC) mechanisms and liquid metals are reported. Regarding the validation of the neoclassically predicted potential asymmetries, its impact on the radial electric field along the flux surface has been successfully validated against Doppler reflectometry measurements. Research on the physics and modelling of plasma core fuelling with pellets and tracer encapsulated solid pellet injection has shown that, although post-injection particle radial redistributions can be understood qualitatively from NC mechanisms, turbulence and fluctuations are strongly affected during the ablation process. Advanced analysis tools based on transfer entropy have shown that radial electric fields do not only affect the radial turbulence correlation length but are also capable of reducing the propagation of turbulence from the edge into the scrape-off layer. Direct experimental observation of long range correlated structures show that zonal flow structures are ubiquitous in the whole plasma cross-section in the TJ-II stellarator. Alfvénic activity control strategies using ECRH and ECCD as well as the relation between zonal structures and AEs are reported. Finally, the behaviour of liquid metals exposed to hot and cold plasmas in a capillary porous system container was investigated.

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“…The results show that the turbulence drive, the Reynolds stress acceleration, was able to provide the necessary perpendicular acceleration; however, a causal relation could not be established. In addition, the calculated neoclassical viscosity and damping times were comparable with the observed ZF relaxation times [63,64]. These results indicate that both turbulent and neoclassical mechanisms, and their mutual interactions, should be considered to achieve a full understanding of the dependences of edge ZFs.…”

Section: (C) Scale-resolved Turbulence Studiessupporting

confidence: 70%

H-mode transition in the TJ-II stellarator plasmas

Estrada¹,

Hidalgo²

2023

Phil. Trans. R. Soc. A.

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Since the first H-mode transitions were observed in TJ-II plasmas in 2008, an extensive experimental effort has been done aiming at better physics understanding of confinement transitions. In this article, an overview of the main findings related to the L-H transition in TJ-II is presented including how the radial electric field is driven, what are the possible mechanisms for turbulence suppression and what are the related temporal and spatial scales that can impact the transition. The trigger of the L-H transition in TJ-II plasmas is found to be more correlated with the development of fluctuating E × B flows than with steady-state E r effects, pointing to the role played by zonal flows in mediating the transition. Experimental evidence supporting the predator–prey relationship between turbulence and flows as the basis for the L-H transition, found for the first time in TJ-II, reinforces this conclusion. Besides, the reduction in the turbulent transport at the transition is detected at the barrier region but also in a wider radial range with weak or even zero E × B flow shear, which points to other mechanisms beyond the turbulence suppression by local sheared flows. This article is part of a discussion meeting issue ‘H-mode transition and pedestal studies in fusion plasmas’.

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On the interplay between turbulent forces and neoclassical particle losses in zonal flow dynamics

Cited by 9 publications

References 31 publications

Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator

Frequency and plasma condition dependent spatial structure of low frequency global potential oscillations in the TJ-II stellarator

Overview of the TJ-II stellarator research programme towards model validation in fusion plasmas

H-mode transition in the TJ-II stellarator plasmas

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