Zonal flows in stellarators in an ambient radial electric field

Mishchenko, A.; Kleiber, R.

doi:10.1063/1.4737580

Cited by 21 publications

(28 citation statements)

References 26 publications

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“…The maximum is reached for times around t = 0, the time at which the neoclassical electric field is close to zero at those radial locations. Finite orbit widths effects of the ambient E r are expected to enhance the damping of the LFO in helical systems [34] in consistency with previous simulations [35] for the TJ-II geometry. The maximum amplitude time delay observed for the different radial locations in figure 9 is due to the inward propagation of the region of small radial electric field associated to electron-to-ion root jump described in previous sections.…”

Section: Gyrokinetic Simulations Of Zonal Flow Relaxation During the supporting

confidence: 90%

Damping of radial electric field fluctuations in the TJ-II stellarator

Velasco¹,

Alonso²,

Calvo³

et al. 2013

Plasma Phys. Control. Fusion

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The drift kinetic equation is solved for low density TJ-II plasmas employing slowly varying, time-dependent profiles. This allows to simulate density ramp-up experiments and to describe from first principles the formation and physics of the radial electric field shear, which is associated to the transition from electron to ion root. We show that the range of frequencies of plasma potential fluctuations in which zonal flows are experimentally observed is neoclassically undamped in a neighborhood of the transition. This makes the electron root regime of stellarators, close to the transition to ion root, a propitious regime for the study of zonal-flow evolution. We present simulations of collisionless relaxation of zonal flows, in the sense of the Rosenbluth and Hinton test, that show an oscillatory behaviour in qualitative agreement with the experiment close to the transition.

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Section: Gyrokinetic Simulations Of Zonal Flow Relaxation During the supporting

confidence: 90%

Damping of radial electric field fluctuations in the TJ-II stellarator

Velasco¹,

Alonso²,

Calvo³

et al. 2013

Plasma Phys. Control. Fusion

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“…The amplification of low frequency ZF-structures in plasma scenarios with reduced Neoclassical viscosity has been observed in TJ-II [138]. In addition, gyrokinetic simulations have shown that radial electric fields may affect the residual level of zonal flows in stellarators [139,140]. Experiments performed in the TJ-II stellarator have shown that long range correlations detected in potential fluctuations, consistent with zonal flows, are amplified either by externally imposed radial electric fields or when approaching the L-H confinement edge transition.…”

Section: Zonal Flows and Radial Electric Fieldsmentioning

confidence: 93%

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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“…A background long-wavelength radial electric field is known to have an effect on both the residual ZF level (Sugama & Watanabe 2009) and also on its oscillation frequency (Mishchenko & Kleiber 2012); then, it is worth checking the effect of using these NCST tools on the ZF evolution with a background electric field included in the simulation. The results of this test for two values of the background electric field are shown in figures 11 and 12.…”

Section: Characterization Of Ncstsmentioning

confidence: 99%

“…Influence of the Krook operator (a), heating source, γ h , (b) and weight smoothing, σ QT (with N QT = 10, f QT = Ω * ) (c), on the linear evolution of the zonal potential component in W7-X equilibrium for different values of parameters including an electric field dφ/dr = r/a 2 . Influence of the Krook operator (a), heating source, γ h , (b) and weight smoothing, σ QT (with N QT = 10, f QT = Ω * ) (c), on the linear evolution of the zonal potential component in a W7-X equilibrium for different values of parameters including an electric field dφ/dr = 2r/a 2 (Mishchenko & Kleiber 2012)…”

mentioning

confidence: 99%

Nonlinear gyrokinetic PIC simulations in stellarators with the code EUTERPE

Sánchez

Mishchenko²,

García-Regaña

et al. 2020

J. Plasma Phys.

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In this work, the first nonlinear particle-in-cell simulations carried out in a stellarator with the global gyrokinetic code EUTERPE using adiabatic electrons and realistic plasma parameters are reported. Several studies are conducted with the aim of enabling reliable nonlinear simulations in stellarators with this code. First, EUTERPE is benchmarked against ORB5 in both linear and nonlinear settings in a tokamak configuration. Next, the use of noise control and stabilization tools, a Krook-type collision operator, markers’ weight smoothing and heating sources is investigated. It is studied in detail how these tools influence the linear growth rate of instabilities in both tokamak and stellarator geometries, and their influence on the linear zonal flow evolution in a stellarator. Then, it is studied how these tools allow improvement of the quality of the results in a set of nonlinear simulations of electrostatic turbulence in a stellarator configuration. Finally, these tools are applied to a W7-X magnetic configuration using experimental plasma parameters.

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Zonal flows in stellarators in an ambient radial electric field

Cited by 21 publications

References 26 publications

Damping of radial electric field fluctuations in the TJ-II stellarator

Damping of radial electric field fluctuations in the TJ-II stellarator

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

Nonlinear gyrokinetic PIC simulations in stellarators with the code EUTERPE

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