3D effects on transport and plasma control in the TJ-II stellarator

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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.

Section: Influence Of Isotope Mass On Plasma Turbulencesupporting

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

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“…A non-axisymmetric E × B shear inducing toroidally localized turbulence with an applied magnetic perturbation field in EAST plasma confinement [13][14][15]. Understanding the 3D interaction between the turbulence and E × B shear is thus the key to uncovering the physics behind the ELM control.…”

Section: Nuclear Fusionmentioning

confidence: 99%

A non-axisymmetric E × B shear inducing toroidally localized turbulence with an applied magnetic perturbation field in EAST

Chen

et al. 2019

The local E × B shear has been demonstrated to be correlated with control of the 3D structure of turbulence in the edge transport barrier (pedestal) on EAST with edge-localized modes (ELMs) suppressed by externally applied 3D magnetic fields. The toroidal variations in turbulence intensity, spectrum width and eddy tilting are found to be correlated with the local E × B shear, and may thus provide the potential mechanism for 3D-field-induced non-axisymmetric E × B shear in regulation of the turbulence. These new findings may significantly advance the understanding of pedestal transport and structure with applied 3D fields for ELM control, which is critical for next-step fusion development.

“…The TJ-II is a four-period, low magnetic shear (Δι ≤ 6 %) stellarator located at CIEMAT, Madrid, Spain [44]. Its major radius, R0, is 1.5 m, and its average minor radius, a0, is ≤ 0.22 m. A set of poloidal, toroidal and vertical coils creates its fully 3-dimensional magnetic-field with bean shaped cross-section, central magnetic field, B(0) ≤ 1.1 T, and total plasma volume of around 1.1 m 3 .…”

Section: Tj-iimentioning

confidence: 99%

Experimental studies and simulations of hydrogen pellet ablation in the stellarator TJ-II

Panadero¹,

McCarthy²,

Koechl

et al. 2018

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Plasma core fuelling is a key issue for the development of steady-state scenarios in large magnetically-confined fusion devices, in particular for helical-type machines. At present, cryogenic pellet injection is the most promising technique for efficient fuelling. Here, pellet ablation and fuelling efficiency experiments, using a compact pellet injector, are carried out in Electron Cyclotron Resonance and Neutral Beam Injection heated plasmas of the stellarator TJ-II. Ablation profiles are reconstructed from light emissions collected by silicon photodiodes and a fast-frame camera system, under the assumptions that such emissions are loosely related to the ablation rate and that pellet radial acceleration is negligible. In addition, pellet particle deposition and fuelling efficiency are determined using density profiles provided by a Thomson Scattering system. Furthermore, experimental results are compared with ablation and deposition profiles provided by the HPI2 pellet code, which is adapted here for the stellarators Wendelstein 7-X (W7-X) and TJ-II. Finally, the HPI2 code is used to simulate ablation and deposition profiles for pellets of different sizes and velocities injected into relevant W7-X plasma scenarios, while estimating the plasmoid drift and the fuelling efficiency of injections made from two W7-X ports.