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

Author

J.A. Alonso, D. Alegre, J. Alonso, R. Antón, A. Arias-Camisón, E. Ascasíbar, A. Baciero, J.M. Barcala, M. Barnes, E. Blanco, L. Bueno, A. Bustos, S. Cabrera, E. de la Cal, I. Calvo, A. Cappa, D. Carralero, R. Carrasco, B. Carreras, R. Castro, A. de Castro, L. Cebrián, M. Chamorro, A.A. Chmyga, P. Colino, J. Duque, F.J. Escoto, T. Estrada, A. Fernández, J. Fraguas, J.M. Fontdecaba, A. Gabriel, L. García, I. García-Cortés, R. García-Gómez, J.M. García-Regaña, G. Godino-Sedano, J. Gómez-Manchón, A. González, A. González-Jerez, V. Guisse, J. Hernández-Sánchez, J. Hernanz, C. Hidalgo, P. Ivanova, A. Jiménez-Denche, D. Jiménez-Rey, G. Kocsis, M. Koepke, A.S. Kozachek, F. Lapayese, M. Liniers, D. López, D. López-Bruna, B. López-Miranda, E. de la Luna, E. Maragkoudakis, F. Martín-Díaz, G. Martín-Gómez, J. Martínez-Fernández, K.J. McCarthy, F. Medina, D. Medina-Roque, M. Medrano, P. Méndez, F.J. Miguel, B. van Milligen, A. Molinero, G. Motojima, S. Mulas, M. Navarro, I. Nedzelskiy, R. Nuñez, M. Ochando, E. Oyarzábal, J.L. de Pablos, F. Palomares, N. Panadero, F.I. Parra, C. Pastor, I. Pastor, A. de la Peña, R. Peralta, A. Pereira, P. Pons-Villalonga, A.B. Portas, E. Poveda, F.J. Ramos, G.A. Rattá, M. Redondo, C. Reynoso, E. Rincón, J. de la Riva, C. Rodríguez-Fernández, A. Ros, E. Sánchez, J. Sánchez, E. Sánchez-Sarabia, J.A. Sebastián, E.R. Solano, A. Soleto, T. Szepesi, F.L. Tabarés, D. Tafalla, H. Takahashi, N. Tamura, H. Thienpondt, A. Tolkachev, V. Tribaldos, R. Unamuno, J. Varela, J. Vega, J.L. Velasco, and I. Voldiner

Subjects
particle transport, fuelling, cryogenic pellet injection, stellarator, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

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 turbulent particle transport simulation, validation of pellet deposition models, density profile shaping for performance control and new experimental techniques for edge turbulence and plasma-neutral interaction.

Published
2024
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2. Overview of the TJ-II stellarator research programme towards model validation in fusion plasmas

Author

C. Hidalgo, E. Ascasíbar, D. Alegre, A. Alonso, J. Alonso, R. Antón, A. Baciero, J. Baldzuhn, J.M. Barcala, L. Barrera, E. Blanco, J. Botija, L. Bueno, S. Cabrera, A. de Castro, E. de la Cal, I. Calvo, A. Cappa, D. Carralero, R. Carrasco, B. Carreras, R. Castro, L. Cebrián, A.A. Chmyga, M. Chamorro, P. Colino, F. de Aragón, M. Drabinskiy, J. Duque, L. Eliseev, F.J. Escoto, T. Estrada, M. Ezzat, F. Fraguas, D. Fernández-Ruiz, J.M. Fontdecaba, A. Gabriel, D. Gadariya, L. García, I. García-Cortés, R. García-Gómez, J.M. García-Regaña, A. González-Jerez, G. Grenfell, J. Guasp, V. Guisse, J. Hernández-Sánchez, J. Hernanz, A. Jiménez-Denche, P. Khabanov, N. Kharchev, R. Kleiber, F. Koechl, T. Kobayashi, G. Kocsis, M. Koepke, A.S. Kozachek, L. Krupnik, F. Lapayese, M. Liniers, B. Liu, D. López-Bruna, B. López-Miranda, U. Losada, E. de la Luna, S.E. Lysenko, F. Martín-Díaz, G. Martín-Gómez, E. Maragkoudakis, J. Martínez-Fernández, K.J. McCarthy, F. Medina, M. Medrano, A.V. Melnikov, P. Méndez, F.J. Miguel, B. van Milligen, A. Molinero, G. Motojima, S. Mulas, Y. Narushima, M. Navarro, I. Nedzelskiy, R. Nuñez, M. Ochando, S. Ohshima, E. Oyarzábal, J.L. de Pablos, F. Palomares, N. Panadero, F. Papoušek, F. Parra, C. Pastor, I. Pastor, A. de la Peña, R. Peralta, A. Pereira, P. Pons-Villalonga, H. Polaino, A.B. Portas, E. Poveda, F.J. Ramos, G.A. Rattá, M. Redondo, C. Reynoso, E. Rincón, C. Rodríguez-Fernández, L. Rodríguez-Rodrigo, A. Ros, E. Sánchez, J. Sánchez, E. Sánchez-Sarabia, S. Satake, J.A. Sebastián, R. Sharma, N. Smith, C. Silva, E.R. Solano, A. Soleto, M. Spolaore, T. Szepesi, F.L. Tabarés, D. Tafalla, H. Takahashi, N. Tamura, H. Thienpondt, A. Tolkachev, R. Unamuno, J. Varela, J. Vega, J.L. Velasco, I. Voldiner, S. Yamamoto, null the TJ-II Team, and TJ-II Team

Subjects
Physics, Nuclear and High Energy Physics, Nuclear engineering, Fusion plasma, Condensed Matter Physics, law.invention, Model validation, stellarator, law, Physics::Plasma Physics, Physics::Space Physics, transport, Stellarator, plasma
Abstract

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 neoclassical (NC) mechanisms and liquid metals are reported. Regarding the validation of the neoclassically predicted potential asymmetries, its impact on the radial electric field along the flux surface has been successfully validated against Doppler reflectometry measurements. Research on the physics and modelling of plasma core fuelling with pellets and tracer encapsulated solid pellet injection has shown that, although post-injection particle radial redistributions can be understood qualitatively from NC mechanisms, turbulence and fluctuations are strongly affected during the ablation process. Advanced analysis tools based on transfer entropy have shown that radial electric fields do not only affect the radial turbulence correlation length but are also capable of reducing the propagation of turbulence from the edge into the scrape-off layer. Direct experimental observation of long range correlated structures show that zonal flow structures are ubiquitous in the whole plasma cross-section in the TJ-II stellarator. Alfvénic activity control strategies using ECRH and ECCD as well as the relation between zonal structures and AEs are reported. Finally, the behaviour of liquid metals exposed to hot and cold plasmas in a capillary porous system container was investigated.

Published
2022
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3. 3D effects on transport and plasma control in the TJ-II stellarator

Author

G. Wolfers, E. Ascasíbar, F. Fernández-Marina, Javier Alonso, Macarena Liniers, F. Martín-Díaz, P. Méndez, A.S. Kozachoek, A. Cappa, Jesús Vega, E. Oyarzábal, K. Sarksian, María Sánchez, M. Medrano, J. Hernández, J. Botija, J. Martínez-Fernández, Marley Vanegas Chamorro, Isabel García-Cortés, B. Momo, K. J. McCarthy, A. Tolkachev, D. Alegre, A. Pereira, L. I. Krupnik, G. Velasco, R. Carrasco, Raul Moreno, Ivan Calvo, U. Losada, F. Medina, E. Sánchez, A.A. Chmyga, G. Martín-Gómez, J. Guasp, F. Castejón, F. J. Miguel, A. Jiménez-Denche, N. Panadero, M. Borchardt, Jesús Herranz, B. Rojo, A. Molinero, L.G. Eliseev, A. Alonso, R. García-Gómez, E. R. Solano, J. Olivares, T. Estrada, Roman Hatzky, M. A. Ochando, J.M. Barcala, R. Merino, F. Lapayese, J.A. Sebastián, Y. Narushima, Shinsuke Satake, L. Melón, E. Sánchez-Sarabia, I. Kirpitchev, A. Martin de Aguilera, A.D. Komarov, M. Martínez, A. de la Peña, F. Martín-Hernández, B. Liu, C. Hidalgo, G. Catalán, Francisco L. Tabarés, E. Rincón, A.B. Martín-Rojo, J. M. Garcia-Regana, B. J. Sun, B. van Milligen, S. Cabrera, J. Sánchez, S. Petrov, A. de Bustos, M. A. Pedrosa, C. Rodríguez, B. Zurro, J. Hernanz, Eric Hollmann, A. Ros, Carlos A. Silva, J.L. de Pablos, S. Tallents, Luis F. Pacios, Ralf Kleiber, A. de Castro, José Luis Velasco, Luis Rios, B. López-Miranda, I. Pastor, E. Poveda, A. E. Petrov, P. Monreal, J. López-Razola, Luis Garcia, G.A. Rattá, M. Navarro, D. López-Bruna, E. de la Cal, J. M. Fontdecaba, A. Portas, M. Yokoyama, D. Tafalla, E. de la Luna, A. Soleto, R. Castro, D. Baião, Andreas Dinklage, A. López-Fraguas, A.V. Melnikov, A. Baciero, E. Blanco, and I. S. Nedzelskiy

Subjects
Physics, Nuclear and High Energy Physics, Magnetic confinement fusion, Plasma confinement, Transport theory, Condensed Matter Physics, 01 natural sciences, 7. Clean energy, Charged particle, 010305 fluids & plasmas, Ion, law.invention, law, Dispersion relation, 0103 physical sciences, Atomic physics, 010306 general physics, Stellarator, Plasma control
Abstract

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.

Published
2017

4. New infrared imaging diagnostic for the Neutral Beam Heating System at the TJ-II stellarator

Author

R. Carrasco, E. Sánchez-Sarabia, J. A. Sebastián, A. Jiménez-Denche, C. Pastor, M. Liniers, I. Pastor, F. Miguel, E. Ascasíbar, B. Rojo, J. A. Quintana, Cristina Castillo Rodríguez, J. Guasp, A. Soleto, F. Martín-Díaz, K. J. McCarthy, and E. de la Cal

Subjects
Materials science, Plasma heating, business.industry, Infrared, Imaging diagnostic, Plasma, law.invention, Heating system, law, Optoelectronics, business, Instrumentation, Deposition (chemistry), Mathematical Physics, Beam (structure), Stellarator
Published
2019
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5. Dynamics of flows and confinement in the TJ-II stellarator

Author

Juan Miguel Insúa Arévalo, Enrique Ascasibar, S. Petrov, A. Martin, M. A. Pedrosa, L. I. Krupnik, A. Cappa, E. Oyarzábal, E. Sánchez, R. Carrasco, J. Hernández, E. R. Solano, A. E. Petrov, A. S. Kozachok, A.D. Komarov, Ralf Kleiber, J. López-Razola, D. López-Bruna, A. Tolkachev, M. Sánchez, E. Sánchez-Sarabia, A. de la Peña, G. Velasco, Kieran J. McCarthy, J.A. Sebastián, A. Soleto, Roman Hatzky, J. Vega, M. Navarro, J. Hernanz, M. A. Ochando, C. Hidalgo, D. Tafalla, P. Méndez, I. Kirpitchev, José Luis Velasco, B. J. Sun, I.S. Nedzelskiy, Luis Garcia, F. Martín-Hernández, J. Martínez-Fernández, M. Medrano, I. Pastor, Carlos A. Silva, Marley Vanegas Chamorro, M. Borchardt, J.A. Jiménez, A. Pereira, C. Rodríguez, A. Baciero, P. Álvarez, P. Monreal, F. Fernández, K. Sarksian, A. Alonso, L. Ríos, J. Herranz, Francisco L. Tabarés, P. García-Sánchez, F. Lapayese, R. García-Gómez, A. Bustos, A. Jiménez-Denche, D. Carralero, D. Alegre, B. van Milligen, J. Sánchez, L. Pacios, M. Tereshchenko, L.G. Eliseev, J. Olivares, L. Melón, A. Portas, J. A. Alonso, E. de la Cal, J. M. Fontdecaba, A.V. Melnikov, E. Blanco, A.A. Chmyga, J. Botija, T. Estrada, J.A. Romero, Ivan Calvo, J.L. de Pablos, R. Castro, Francisco Castejón, B. Rojo, E. Rincón, G. Catalán, G. Wolfers, F. Martín-Díaz, F. Medina, A. López-Fraguas, M. Liniers, S. da Graca, A.B. Martín-Rojo, B. Zurro, A. Ros, J. Guasp, and D. Baiao

Subjects
Physics, Nuclear and High Energy Physics, Work (thermodynamics), Turbulence, Flow (psychology), Observable, Mechanics, Condensed Matter Physics, law.invention, Physics::Fluid Dynamics, Viscosity, law, Relaxation (physics), Statistical physics, Shear flow, Stellarator
Abstract

This work deals with the results on flow dynamics in TJ-II plasmas under Li-coated wall conditions, which produces low recycling and facilitates the density control and access to improved confinement transitions. The low-density transition, characterized by the emergence of the shear flow layer, is described from first principles and within the framework of neoclassical theory. The vanishing of the neoclassical viscosity when approaching the transition from below explains the observation of a number of turbulent phenomena reported in TJ-II in recent years; a unifying picture is provided in which zonal, i.e. large scale, radially structured, perturbations are observable when the neoclassical damping is sufficiently small. Preliminary linear, collisionless gyrokinetic simulations are carried out to assess that the measured time scale of relaxation of such perturbations is reasonably understood theoretically. In higher density regimes, the physical mechanisms behind the L–H transition have been experimentally studied. The spatial, temporal and spectral structure of the interaction between turbulence and flows has been studied close to the L–H transition threshold conditions. The temporal dynamics of the turbulence-flow interaction displays a predator–prey relationship and both radial outward and inward propagation velocities of the turbulence-flow front have been measured. Finally, a non-linear relation between turbulent fluxes and gradients is observed.

Published
2013

6. Overview of TJ-II experiments

Author

T. Madeira, G. Wolfers, J. López-Razola, A.V. Melnikov, A. Molinero, E. Blanco, A. Baciero, J. Martínez-Fernández, P. Álvarez, F. Martín-Díaz, Luis Garcia, F. Medina, J. Olivares, A. Soleto, E. Rincón, M. Weber, J. Vega, A. Alonso, I.S. Nedzelskiy, A. Petrov, M. Medrano, I. Pastor, Carlos A. Silva, G. Catalán, G. Sánchez-Burillo, J.A. Romero, J.A. Jiménez, A. Pereira, M. Acedo, A. Portas, D. Tafalla, L. Pacios, A. Cappa, A. Tolkachev, P. Méndez, J.A. Sebastián, J. A. Alonso, F. Martín-Hernández, S. Petrov, E. de la Cal, Francisco Castejón, Marley Vanegas Chamorro, B. Zurro, E. Oyarzábal, C. Rodríguez, L. Esteban, Jorge Ferreira, D. Alegre, R. Jiménez-Gómez, A. Ros, M. Liniers, A. S. Kozachok, A.B. Martín-Rojo, J. M. Garcia-Regana, S. González, B. Rojo, R. García-Gómez, E. R. Solano, J. Hernanz, J. Botija, T. Happel, J. Guasp, A. D. Komarov, I. Kirpitchev, K. Sarksian, D. Baiao, Juan Miguel Insúa Arévalo, Ivan Calvo, J.M. Fontdecaba, José Luis Velasco, Benjamin A. Carreras, Antonio Gómez-Iglesias, P. García-Sánchez, A.A. Chmyga, Francisco L. Tabarés, F. Lapayese, T. Estrada, J. M. Reynolds, L. Melón, J. Sanchez, J. Tera, J. Herranz, A. Bustos, G.A. Rattá, D. Carralero, B. van Milligen, M. Navarro, M. A. Ochando, A. López-Fraguas, D. López-Bruna, A. de la Peña, R. Castro, L. I. Krupnik, E. Sánchez, R. Carrasco, M. Sánchez, G. Velasco, E. Mirones, J.L. de Pablos, Enrique Ascasibar, M. A. Pedrosa, A. Jiménez-Denche, L.G. Eliseev, E. Sánchez-Sarabia, L. Barrera, Kieran J. McCarthy, C. Hidalgo, and L. Ríos

Subjects
Physics, Nuclear and High Energy Physics, Turbulence, Magnetic confinement fusion, Mechanics, Plasma, Condensed Matter Physics, law.invention, Coupling (physics), Physics::Plasma Physics, law, Electric field, Physics::Space Physics, Limiter, Atomic physics, Topology (chemistry), Stellarator
Abstract

This paper presents an overview of experimental results and progress made in investigating the link between magnetic topology, electric fields and transport in the TJ-II stellarator. The smooth change from positive to negative electric field observed in the core region as the density is raised is correlated with global and local transport data. A statistical description of transport is emerging as a new way to describe the coupling between profiles, plasma flows and turbulence. TJ-II experiments show that the location of rational surfaces inside the plasma can, in some circumstances, provide a trigger for the development of core transitions, providing a critical test for the various models that have been proposed to explain the appearance of transport barriers in relation to magnetic topology. In the plasma core, perpendicular rotation is strongly coupled to plasma density, showing a reversal consistent with neoclassical expectations. In contrast, spontaneous sheared flows in the plasma edge appear to be coupled strongly to plasma turbulence, consistent with the expectation for turbulent driven flows. The local injection of hydrocarbons through a mobile limiter and the erosion produced by plasmas with well-known edge parameters opens the possibility of performing carbon transport studies, relevant for understanding co-deposit formation in fusion devices.

Published
2011
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7. Assessment of health-related quality of life in chronic dialysis patients with the COOP/WONCA charts.

Author

Martín-Díaz F, Reig-Ferrer A, and Ferrer-Cascales R

Subjects
Adult, Factor Analysis, Statistical, Female, Hemodialysis Units, Hospital, Humans, Kidney Failure, Chronic psychology, Language, Male, Middle Aged, Psychometrics, Reproducibility of Results, Spain, Kidney Failure, Chronic therapy, Quality of Life, Renal Dialysis psychology, Surveys and Questionnaires
Abstract

Background: The aim of the present work was to determine the health-related quality of life (HRQOL) of our patients on hemodialysis using the COOP/WONCA charts. A further aim was to explore its psychometric characteristics., Methods: The present study included all patients attending the hemodialysis unit of our hospital. The comparative study of the results was conducted with other population groups in which this questionnaire has been applied previously (primary-care patients, their accompanying persons, pregnant women, Alzheimer patient carers and drug addicts). The dimensional structure of the questionnaire was explored by factorial analysis of principal components, and internal consistency was evaluated with the Cronbach alpha factor. Concurrent validity was determined by comparative analysis of the results of the COOP/WONCA charts with those of another questionnaire, the 36-item short form of the Quality of Life Score (SF-36). To do so, 60 randomly chosen patients completed both questionnaires., Results: 98.9% of patients completed the COOP/WONCA charts in their entirety. The mean scores of all the charts, with the exception of overall health, are in the range of what could be called 'favorable area of quality of life' (below 3). With respect to the rest of the groups, the dialysis patients had the best scores on the 'feelings' and 'social activities' charts and none of the worst ones. The joint factorial analysis revealed that the questionnaire has a 3-factor structure: factor 1 or daily functioning, factor 2 or quality of life and health, factor 3 or the psychosocial factor. The Cronbach alpha value for the 9 charts was 0.766. All the correlations between equivalent dimensions of questionnaires COOP/WONCA and SF-36 were statistically significant (p < 0.01). The convergent validity mean was 0.57 and the discriminant validity mean was 0.22, appreciably lower than convergent validity., Conclusions: This study shows that the process of psychological adaptation to problems deriving from dialysis is satisfactory. Moreover, the COOP/WONCA charts are a useful instrument for the determination of the HRQOL in hemodialysis patients without losing psychometric quality., (Copyright 2006 S. Karger AG, Basel.)

Published
2006
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8. [Sexual function and quality of life in hemodialysis male patients].

Author

Martín-Díaz F, Reig-Ferrer A, and Ferrer-Cascales R

Subjects
Aged, Erectile Dysfunction epidemiology, Humans, Male, Middle Aged, Erectile Dysfunction etiology, Kidney Failure, Chronic physiopathology, Kidney Failure, Chronic therapy, Quality of Life, Renal Dialysis adverse effects, Sexuality
Abstract

Background: The sexual dysfunction is a highly prevalent problem among uremic men that limits their quality of life. The aim of this study was to determine the sexual function in chronic renal failure in males patients on hemodialysis and to find the nature of the problem. Also, we explored the impact of sexual dysfunction on health-related quality of life., Methods: 103 male patients older than 18 years and receiving HD treatment were studied. The sexual function was evaluated with the International Index of Erectile Function, and the health-related quality of life was quantified with the COOP-WONCA Charts, both in their Spanish versions., Results: 47% of the patients didn't have any kind of sexual activity. These ones presented a more advanced age (p < 0.001), a longer stay on dialysis (p < 0.001), a greater comorbidity index (p < 0.05) and smaller levels of seric albumin (p < 0.05). The sexually active patients presented a better physical fitness (p < 0.001) and overall health (p < 0.05), and a smaller difficulty to carry out the daily activities (p < 0.05) and pain (p < 0.05). A 40% of the patients with some kind of sexual function had a good erectile function, the 34.5% suffered a slight erectile dysfunction, the 16.4% a moderate one and the 9.1% a severe one. Multiple linear regression analysis demonstrated that the main determinant of the sexual activity was the age, followed by the physical fitness and the time on HD (32.7% of the variance explained). We found statistically significative correlation between the total score of IIEF and felings (r = -0.34; p < 0.05), daily activities (r = -0.27; p < 0.05), social activities (r = -0.30; p < 0.05), social support (r = -0.45; p < 0.01) and quality of life (r = -0.29; p < 0.05). The patients without sexual activity didn't perceive their deficiency as a problem and considered this situation inherent to the ageing process., Conclusions: The sexual dysfunction is a highly prevalent problem in the uremic male, but it doesn't have to be necessarily associated to a serious deterioration of the HRQOL. In this way, the presence or not of sexual activity doesn't present significant effect on the things that one has or wants to do. With everything, the patient without sexual activity frequently has advanced age, refers worse state of health and presents more problems of physical functioning and at the moment of taking to daily activities.

Published
2006

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