Explanipedia

Density profiles in stellarators: an overview of particle transport, fuelling and profile shaping studies at TJ-II Open

A. Alonso, D. Alegre, A. Alonso, R. Antón, A. Arias-Camisón , et al. · 2024

We provide an overview of activities carried out at the TJ-II stellarator for improving our understanding of- and developing plasma physics models for particle density profiles in stellarators. Namely, we report on recent progress in turbu…

Multi-pellet injection into the NBI-heated phase of TJ-II plasmas Open

K. J. McCarthy, I. Garcı́a-Cortés, A. Alonso, A. Arias-Camisón, E. Ascasíbar , et al. · 2024

A pellet-induced enhanced confinement (PiEC) phase, with general characteristics similar to those reported for the stellarator W7-X, is observed after single pellet injection (>10 19 H atoms) into the neutral beam injection heated phase of…

Enhanced confinement induced by pellet injection in the stellarator TJ-II Open

I. Garcı́a-Cortés, K. J. McCarthy, T. Estrada, V. Tribaldos, D. Medina-Roque , et al. · 2023

Enhanced confinement is observed in neutral beam injector (NBI)-heated hydrogen discharges made in the stellarator TJ-II after the injection of a single cryogenic fuel pellet into the plasma core. In addition to the expected increase in el…

Allergens Responsible for Anaphylaxis After Olive Fruit Ingestion Open

M Prados-Castaño, M Reguero-Capilla, B Bartolomé, Carlos Pastor‐Vargas, M. A. Ochando , et al. · 2022

the saline control) to Dermatophagoides pteronyssinus, cat and dog dander, and Olea europea and grass pollen.Prick-by-prick test with spices (pepper, cumin, oregano, thyme) and garlic were negative.We performed prick-by-prick test with oli…

Rational surfaces, flows and radial structure in the TJ-II stellarator Open

B. Ph. van Milligen, I. Voldiner, B. A. Carreras, L. García, M. A. Ochando · 2022

In this work, we report on the results obtained by measuring several turbulent quantities well inside the plasma edge by means of a Langmuir probe during dynamical rotational transform scans in the TJ-II stellarator, while applying a radia…

A lithium laser-ablation based time-of-flight (LILA-TOF) diagnostic for measuring plasma edge ion temperature and toroidal plasma rotation Open

B. López-Miranda, F.L. Tabarés, K. J. McCarthy, A. Baciero, D. Tafalla , et al. · 2021

A new method for studying the thermalization and transport of injected impurities at the edge of hot plasma, (considering the last closed magnetic surface, the free path is between 1 and 2 cm approx.) under no perturbative conditions, is p…

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

C. Hidalgo, E. Ascasíbar, D. Alegre, A. Alonso, A. Alonso , et al. · 2021

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 neoclassi…

Experimental observation of the geodesic acoustic frequency limit for the NBI-driven Alfvén eigenmodes in TJ-II Open

L.G. Eliseev, A. V. Melnikov, E. Ascasíbar, Á. Cappa, М.А. Drabinskiy , et al. · 2021

We study Alfvén eigenmodes (AEs) in the TJ-II heliac in hydrogen plasmas heated by hydrogen co-field neutral beam injector. Taking advantage of the unique TJ-II flexibility in a varying plasma current, we have observed strong variation of …

Effect of ECH/ECCD on energetic-particle-driven MHD modes in helical plasmas Open

S. Yamamoto, K. Nagasaki, K. Nagaoka, J. Varela, Á. Cappa , et al. · 2020

The effect of electron cyclotron heating (ECH) and electron cyclotron current drive (ECCD) on energetic-particle (EP)-driven magnetohydrodynamic (MHD) modes is studied in the helical devices LHD, TJ-II and Heliotron J. We demonstrate that …

Overview of recent TJ-II stellarator results Open

E. Ascasíbar, Daniel Moreno Alba, D. Alegre, A. Alonso, A. Alonso , et al. · 2019

The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence chara…

Generation and transport of atomic lithium during the exposure of liquid metals to hot plasmas in TJ-II Open

F.L. Tabarés, E. Oyarzábal, D. Tafalla, A.B. Martín-Rojo, M. A. Ochando , et al. · 2018

A full campaign of comparative Li/LiSn/Sn testing has been initiated in TJ-II stellarator plasmas. Solid and liquid samples of the three candidates, in a Capillary Porous System (CPS) arrangement, have been exposed to the edge plasma and t…

Stellarator nonlinearly saturated periodicity-breaking ideal magnetohydrodynamic equilibrium states Open

W.A. Cooper, D. Löpez‐Bruna, M. A. Ochando, F. Castejón, J. P. Graves , et al. · 2018

The relaxation of the constraint of periodicity imposed by the external confining magnetic field coils in a nominally 4-field period Helias Advanced Stellarator configuration produces weak periodicity-breaking deformations of the plasma. T…

Comparative studies of liquid metals for an alternative divertor target in a fusion reactor Open

F.L. Tabarés, E. Oyarzábal, D. Tafalla, A.B. Martín-Rojo, I. Pastor , et al. · 2017

Two liquid metals (LM), Li and LiSn (20:80 at), presently considered as alternative materials for the divertor target of a fusion reactor, have been exposed to the plasma in a capillary porous system (CPS) arrangement in TJ-II. A negligibl…

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

F. Castejón, D. Alegre, A. Alonso, A. Alonso, E. Ascasíbar , et al. · 2017

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 …

Analysis of higher harmonics on bidirectional heat pulse propagation experiment in helical and tokamak plasmas Open

T. Kobayashi, K. Ida, S. Inagaki, H. Tsuchiya, N. Tamura , et al. · 2017

In this contribution we analyze modulation electron cyclotron resonance heating (MECH) experiment and discuss higher harmonic frequency dependence of transport coefficients. We use the bidirectional heat pulse propagation method, in which …

Experimental tests of LiSn alloys as potential liquid metal for the divertor target in a fusion reactor Open

F.L. Tabarés, E. Oyarzábal, A.B. Martín-Rojo, D. Tafalla, A. de Castro , et al. · 2016

The first experiments of exposure of a LiSn alloy (Li/Sn atomic ratio= 20/80) to a hydrogen plasma in TJ-II are here presented. Solid and liquid samples have been inserted at the edge and evidence of sample melting of a solid sample during…

Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices Open

J. L. Velasco, I. Calvo, S. Satake, A. Alonso, M. Nunami , et al. · 2016

Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, and this is particularly the case of helical reactors, whose low-collisionality ion-root operation scenarios usuall…

Parallel impurity dynamics in the TJ-II stellarator Open

A. Alonso, J. L. Velasco, I. Calvo, T. Estrada, J.M. Fontdecaba , et al. · 2016

We review in a tutorial fashion some of the causes of impurity density\nvariations along field lines and radial impurity transport in the moment\napproach framework. An explicit and compact form of the parallel inertia force\nvalid for arb…

Transport analysis of different charge/mass impurities injected by laser blow-off in ECRH heated plasmas of TJ-II Open

B. Zurro, E.M. Hollmann, A. Baciero, M. A. Ochando, R. Dux , et al. · 2016

Effect of fast electrons on the stability of resistive interchange modes Open

L. García, M. A. Ochando, B. A. Carreras, D. Carralero, C. Hidalgo , et al. · 2016

Magnetic well scan and confinement in the TJ-II stellarator Open

Adriana M. de Aguilera, F. Castejón, E. Ascasíbar, E. Blanco, E. de la Cal , et al. · 2015

The magnetic well is the main stabilising mechanism in the TJ-II stellarator, since this is an almost shearless device. TJ-II has the capability of varying its magnetic configuration by changing the currents of its coils, allowing one to c…

Transport, stability and plasma control studies in the TJ-II stellarator Open

J. Sánchez, D. Alegre, A. Alonso, A. Alonso, Pedro Álvarez , et al. · 2015

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Dynamics of magnetic islands and confinement transitions in TJ-II Open

Julio J. Martinell, D. Löpez‐Bruna, M. A. Ochando · 2015

Bolometric observations over a large number of discharges under very different conditions in the TJ-II Heliac, together with magnetic and line-emission diagnostics have indicated that the plasma behavior near rational magnetic surfaces is …

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