The effects of electron cyclotron heating and current drive on toroidal Alfven eigenmodes in tokamak plasmas

Dedicated studies performed for toroidal Alfvén eigenmodes (TAEs) in ASDEX-Upgrade (AUG) discharges with monotonic q-profiles have shown that electron cyclotron resonance heating (ECRH) can make TAEs more unstable. In these AUG discharges, energetic ions driving TAEs were obtained by ion cyclotron resonance heating (ICRH). It was found that off-axis ECRH facilitated TAE instability, with TAEs appearing and disappearing on timescales of a few milliseconds when the ECRH power was switched on and off. On-axis ECRH had a much weaker effect on TAEs, and in AUG discharges performed with co- and counter-current electron cyclotron current drive (ECCD), the effects of ECCD were found to be similar to those of ECRH. Fast ion distributions produced by ICRH were computed with the PION and SELFO codes. A significant increase in Te caused by ECRH applied off-axis is found to increase the fast ion slowing-down time and fast ion pressure causing a significant increase in the TAE drive by ICRH-accelerated ions. TAE stability calculations show that the rise in Te causes also an increase in TAE radiative damping and thermal ion Landau damping, but to a lesser extent than the fast ion drive. As a result of the competition between larger drive and damping effects caused by ECRH, TAEs become more unstable. It is concluded, that although ECRH effects on AE stability in present-day experiments may be quite significant, they are determined by the changes in the plasma profiles and are not particularly ECRH specific.EURATOM 633053RCUK Energy Programme P012450/

First absolute measurements of fast-ion losses in the ASDEX Upgrade tokamak

A new diagnostic technique that allows to obtain absolute fluxes of fast-ion losses measured with absolutely calibrated scintillator based fast-ion loss detectors (FILD) is presented here. First absolute fluxes of fast-ion losses have been obtained in the ASDEX Upgrade tokamak. An instrument function that includes the scintillator efficiency, collimator geometry, optical transmission and camera efficiency has been constructed. The scintillator response to deuterium ions in the relevant energy range of fast-ions has been characterized using a tandem accelerator. Absolute flux of neutral beam injection (NBI) prompt losses has been obtained in magnetohydrodynamic quiescent plasmas. The temporal evolution of the heat load measured with FILD follows that measured at the FILD entrance obtained with an Infra-Red camera looking at the FILD detector head. ASCOT simulations are in good agreement with the absolute heat load of NBI prompt losses measured with FILD.Ministerio de Economía, Industria y Competitividad RYC-2011-09152, FIS2015-69362-P, ENE2012-31087EUROfusion Consortium PCIG11-GA-2012- 321455Comunidad Europea de la Energía Atómica 63305

Dependence on plasma shape and plasma fueling for small ELM regimes in TCV and ASDEX Upgrade

Within the EUROfusion MST1 Work Package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (ne,sep/nG ∼ 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a Double Null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.EURATOM 63305

Caracterización morfológica y composición química de chayotas (Sechium edule) cultivadas en las Islas Canarias (España)

Se analizaron características morfológicas relacionadas con el fruto, espinas, endocarpio y semilla, así como parámetros fisicoquímicos y nutricionales (humedad, proteínas, ºBrix, fibra alimentaria, cenizas, pH, acidez, ácido ascórbico, compuestos fenólicos totales, minerales: Na, K, Ca y Mg y elementos traza: Fe, Cu, Zn y Mn), en muestras de chayota (Sechium edule) pertenecientes a 7 entradas cultivadas en las islas de Tenerife y La Palma (España) y cosechadas durante el período comprendido entre junio y noviembre de 2005. Se observaron diferencias importantes en la composición química y características morfológicas entre las diferentes entradas de chayota estudiadas. La entrada 4 destacó por su alto contenido en minerales y sólidos solubles totales (ºBrix) y bajo contenido en agua, mientras que la entrada 1 presentó altos contenidos en Na, cenizas y ácido ascórbico. El contenido de humedad y de ácido ascórbico varió en función de la parte del fruto analizada, sin embargo, los contenidos de compuestos fenólicos y de cenizas no fueron dependientes de las partes. La fecha de muestreo mostró una gran influencia sobre la composición química, observándose las mayores diferencias en las muestras cosechadas en el mes otoñal de noviembre respecto a las restantes cosechadas en meses estivales. El análisis discriminante permitió diferenciar las muestras de chayota en función de la entrada y fecha de muestreo, por lo que es una herramienta muy útil para la caracterización de muestras

Caracterización morfológica y composición química de chayotas (Sechium edule) cultivadas en las Islas Canarias (España)

Se analizaron características morfológicas relacionadas con el fruto, espinas, endocarpio y semilla, así como parámetros fisicoquímicos y nutricionales (humedad, proteínas, ºBrix, fibra alimentaria, cenizas, pH, acidez, ácido ascórbico, compuestos fenólicos totales, minerales: Na, K, Ca y Mg y elementos traza: Fe, Cu, Zn y Mn), en muestras de chayota (Sechium edule) pertenecientes a 7 entradas cultivadas en las islas de Tenerife y La Palma (España) y cosechadas durante el período comprendido entre junio y noviembre de 2005. Se observaron diferencias importantes en la composición química y características morfológicas entre las diferentes entradas de chayota estudiadas. La entrada 4 destacó por su alto contenido en minerales y sólidos solubles totales (ºBrix) y bajo contenido en agua, mientras que la entrada 1 presentó altos contenidos en Na, cenizas y ácido ascórbico. El contenido de humedad y de ácido ascórbico varió en función de la parte del fruto analizada, sin embargo, los contenidos de compuestos fenólicos y de cenizas no fueron dependientes de las partes. La fecha de muestreo mostró una gran influencia sobre la composición química, observándose las mayores diferencias en las muestras cosechadas en el mes otoñal de noviembre respecto a las restantes cosechadas en meses estivales. El análisis discriminante permitió diferenciar las muestras de chayota en función de la entrada y fecha de muestreo, por lo que es una herramienta muy útil para la caracterización de muestras.Morphological characteristics related to the fruit, thorns, endocarp and seed, as well as physicochemical and nutritional parameters (moisture, protein, ºBrix, fiber, ash, pH, acidity, ascorbic acid, total phenolics, minerals: Na, K, Ca and Mg, and trace elements: Fe, Cu, Zn and Mn) were analyzed in samples of chayote (Sechium edule) belonging to 7 accessions grown on the islands of Tenerife and La Palma (Spain) and harvested during the period between June and November 2005. Significant differences in chemical composition and morphology between the chayote accessions studied were observed. The accession 4 features a high mineral content and soluble solids (Brix degree) and low water content, while the accession 1 had high contents of Na, ash and ascorbic acid. The moisture content and ascorbic acid varied depending on the portion of the fruit analyzed, however, the contents of phenolic compounds and ash were not affected. The sampling date showed a great influence on the chemical composition, the greatest differences observed in the samples harvested in the month of November autumn, with respect to the remaining summer months. Discriminant analysis allowed differentiate samples chayota according to the accession and sampling date, so it is a very useful tool for the characterization of these samples