Particle transport after pellet injection in the TJ-II stellarator

Velasco, J. L.; McCarthy, K. J.; Panadero, N.; Satake, S.; López‐Bruna, D.; Alonso, A.; Calvo, I.; Dinklage, A.; Estrada, T.; Fontdecaba, J. M.; Hernández, J. M.; García, R.; Medina, F.; Ochando, M. A.; Pastor, I.; Perfilov, S.V.; Sánchez, E.; Soleto, A.; Zhezhera, A.

doi:10.1088/0741-3335/58/8/084004

Cited by 15 publications

(20 citation statements)

References 36 publications

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“…averaged density is significantly slower (not shown in figure 2, see [16]). The plasma electric field undergoes a rapid evolution as observed with Doppler reflectometry in the plasma edge and the HIBP I and II in more interior positions (Fig.…”

Section: Experimental Set-up and Observationsmentioning

confidence: 89%

Observation of Oscillatory Radial Electric Field Relaxation in a Helical Plasma

Alonso¹,

Sánchez²,

Calvo³

et al. 2017

Phys. Rev. Lett.

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Measurements of the relaxation of a zonal electrostatic potential perturbation in a nonaxisymmetric magnetically confined plasma are presented. A sudden perturbation of the plasma equilibrium is induced by the injection of a cryogenic hydrogen pellet in the TJ-II stellarator, which is observed to be followed by a damped oscillation in the electrostatic potential. The waveform of the relaxation is consistent with theoretical calculations of zonal potential relaxation in a nonaxisymmetric magnetic geometry. The turbulent transport properties of a magnetic confinement configuration are expected to depend on the features of the collisionless damping of zonal flows, of which the present Letter is the first direct observation.

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Section: Experimental Set-up and Observationsmentioning

confidence: 89%

Observation of Oscillatory Radial Electric Field Relaxation in a Helical Plasma

Alonso¹,

Sánchez²,

Calvo³

et al. 2017

Phys. Rev. Lett.

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“…No measurements of the electric field radial profile were available in that series of discharges. The simulation in this case is started with the initial condition described in (4) to emulate the situation occurring when a pellet is injected in the plasma, which suddenly increases the density at the radial location where the deposition of the particles of the pellet takes place, which is localized radially (see [46]). This initial condition in the density produces a perturbation to the plasma potential, which is obtained after the solution of the QNE in the first step of the simulation.…”

Section: Influence Of Collisionsmentioning

confidence: 99%

Oscillatory relaxation of zonal flows in a multi-species stellarator plasma

Sánchez¹,

Calvo²,

Velasco³

et al. 2018

Plasma Phys. Control. Fusion

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The low frequency oscillatory relaxation of zonal potential perturbations is studied numerically in the TJ-II stellarator (where it was experimentally detected for the first time). It is studied in full global gyrokinetic simulations of multi-species plasmas. The oscillation frequency obtained is compared with predictions based on single-species simulations using simplified analytical relations. It is shown that the frequency of this oscillation for a multi-species plasma can be accurately obtained from single-species calculations using extrapolation formulas. The damping of the oscillation and the influence of the different inter-species collisions is studied in detail. It is concluded that taking into account multiple kinetic ions and electrons with impurity concentrations realistic for TJ-II plasmas allows to account for the values of frequency and damping rate in zonal flows relaxations observed experimentally.

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“…This interest has triggered a set of inter-machine comparative pellet fuelling studies [24,25] whose goal is to achieve a detailed understanding of pellet ablation mechanisms and subsequent particle transport. First core plasma fuelling experiments, using a cryogenic pellet injector system and associated diagnostics have been performed in the TJ-II stellarator, which has enabled particle fuelling and transport experiments in this device [26].…”

Section: Plasma Fuelling Experiments and Neutrals Dynamicsmentioning

confidence: 99%

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

Castejón¹,

Alegre²,

Alonso³

et al. 2017

Nucl. Fusion

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The effects of 3D geometry are explored in TJ-II from two relevant points of view: neoclassical transport and modification of stability and dispersion relation of waves. Particle fuelling and impurity transport are studied considering the 3D transport properties, paying attention to both neoclassical transport and other possible mechanisms. The effects of the 3D magnetic topology on stability, confinement and Alfvén Eigenmodes properties are also explored, showing the possibility of controlling Alfvén modes by modifying the configuration; the onset of modes similar to geodesic acoustic modes are driven by fast electrons or fast ions; and the weak effect of magnetic well on confinement. Finally, we show innovative power exhaust scenarios using liquid metals.

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Particle transport after pellet injection in the TJ-II stellarator

Cited by 15 publications

References 36 publications

Observation of Oscillatory Radial Electric Field Relaxation in a Helical Plasma

Observation of Oscillatory Radial Electric Field Relaxation in a Helical Plasma

Oscillatory relaxation of zonal flows in a multi-species stellarator plasma

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

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