Transport in threshold plasmas for a confinement transition in the TJ-II stellarator

López‐Bruna, D.; Velasco, J. L.; Ochando, M. A.; Guasp, J.; Löpez‐Fraguas, A.; Ascasíbar, E.; Liniers, M.; Estrada, T.; Fontdecaba, J. M.; Pastor, I.; Tafalla, D.; Medina, F.; Eliseev, L.G.; Melnikov, A. V.; Perfilov, S.V.; Herranz, J.; Zurro, B.; McCarthy, K. J.; Tabarés, F.L.

doi:10.1088/0741-3335/55/1/015001

Cited by 11 publications

(7 citation statements)

References 38 publications

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“…It is known that the formation of transport barriers in TJ-II is promoted when low order magnetic resonances are placed in the appropriate plasma region. The stability of such barriers is subject to the MHD stability of the corresponding magnetic resonances [43] and a close relationship has been identified between abrupt changes in transport (in the form of transport pulses or the formation of transport barriers), MHD activity and the location of magnetic resonances. Now, applying a novel causality detection technique (the entropy transfer) to quantify the information transfer between magnetic oscillations and locally measured plasma rotation velocity related to ZFs, it is confirmed that magnetic oscillations associated with rational surfaces play an important and active role in confinement transitions [44].…”

Section: Plasma Flows and Electromagnetic Effectsmentioning

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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Section: Plasma Flows and Electromagnetic Effectsmentioning

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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“…Figure 2 shows power balances for the discharges #19065 and #30047. Discharge #19065 has been discussed in [14]. Discharge #30047 corresponds to a configuration of smaller effective helical ripple for which non-local effects are expected to be smaller.…”

Section: Tj-iimentioning

confidence: 99%

Inter-machine validation study of neoclassical transport modelling in medium- to high-density stellarator-heliotron plasmas

et al. 2013

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An inter-machine dataset covering devices of different size and a variety of magnetic configurations is comprehensively analysed to assess the ranges of validity of neoclassical (NC) transport predictions in medium-to high density, high temperature discharges. A recently concluded benchmarking of calculations of transport coefficients from local NC theory [1] allows now a quantitative experimental energy transport study. While in earlier inter-machine studies of NC transport in 3D devices the electron energy transport at low densities has been investigated [2], this study focuses on the energy transport at medium to higher densities as anticipated when approaching reactor conditions. The validation approach as done here is to compare two fluxes: first, the 'NC flux' is determined with the NC transport coefficients and the gradients of the experimental density and temperature profiles. Second, the sources from deposition calculations considering heating and particle sources (the latter where available) yield the 'experimental flux'. Both fluxes are compared and the NC radial electric field E

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“…A spontaneous H-mode was observed in TJ-II [7]. Two main types of the L-H transitions were found, fast transitions [7][8][9] and the so-called L-I-H transitions [10]. This paper focuses on fast transitions.…”

Section: Introductionmentioning

confidence: 99%

Changes in plasma potential and turbulent particle flux in the core plasma measured by heavy ion beam probe during L–H transitions in the TJ-II stellarator

Melnikov

Eliseev

Estrada³

et al. 2013

Nucl. Fusion

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Plasma potential and turbulent particle flux ΓE×B in the plasma core were measured for the first time during L–H/H–L transitions in the TJ-II heliac using a heavy ion beam probe. The L–H transition is characterized by a simultaneous potential drop ∼−100 V over the whole plasma radius, formation of density pedestal and a strong radial electric field Er between −100 to −150 V cm−1 in the edge (0.8 < ρ < 0.9), strong suppression of the broadband density and potential oscillations and of ΓE×B in the edge and core plasma.

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Transport in threshold plasmas for a confinement transition in the TJ-II stellarator

Cited by 11 publications

References 38 publications

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

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

Inter-machine validation study of neoclassical transport modelling in medium- to high-density stellarator-heliotron plasmas

Changes in plasma potential and turbulent particle flux in the core plasma measured by heavy ion beam probe during L–H transitions in the TJ-II stellarator

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