Electron Bernstein waves emission in the TJ-II Stellarator

Taking advantage of the electron Bernstein waves heating (EBWH) system of the TJ-II stellarator, an electron Bernstein emission (EBE) diagnostic was installed. Its purpose is to investigate the B-X-O radiation properties in the zone where optimum theoretical EBW coupling is predicted. An internal movable mirror shared by both systems allows us to collect the EBE radiation along the same line of sight that is used for EBW heating. The theoretical EBE has been calculated for different orientations of the internal mirror using the TRUBA code as ray tracer. A comparison with experimental data obtained in NBI discharges is carried out. The results provide a valuable information regarding the experimental O-X mode conversion window expected in the EBW heating experiments. Furthermore, the characterization of the radiation polarization shows evidence of the underlying B-X-O conversion process.Comment: 21 pages, 14 figure

Topography influence on horizontal distribution of ichthyoplankton in neritic and oceanic waters in the surroundings of Cape Palos - Hormigas Islands marine reserve (Murcia, southeast Spain)

The present study examines the relationships between the horizontal distribution of ichthyoplankton populations and submarine topography, in both neritic and oceanic waters of Cape Palos - Hormigas Islands Marine Reserve (southeast Spain). Larvae from self-spawners (Sardina pilchardus, Walbaum, 1792; Gobiidae and Sparidae) constituted the shallow community which dominated neritic waters, whereas larvae of Myctophidae (Benthosema glaciale, Reinhardt, 1837, and Lampanyctinae) constituted another community present over the slope and beyond it. Such distribution is strongly related to bathymetry and imitated adult distribution. Variations of this general model along the coast reflects variations in slope width. Ichthyoplancton distribution suggested the presence of a haline front in the zone, such as the one described in the Catalan and Balearic Seas, responsible for limited dispersal (coast-ocean) of larval fishes (Sabatés, 1990).El presente estudio muestra la relación existente entre la distribución horizontal de los poblamientos de ictioplancton y la topografía submarina, en aguas neríticas y oceánicas del entorno de la reserva marina de cabo de Palos - islas Hormigas. Las larvas de peces que frezan sobre la plataforma (Sardina pilchardus Walbaum, 1792; Gobiidae y Sparidae) dominaron las estaciones someras, mientras que las larvas de Myctophidae (Benthosema glaciale, Reinhardt, 1837 y Lampanyctinae) constituyeron un poblamiento que dominó las estaciones situadas sobre y por fuera del talud continental. Esta distribución horizontal de los poblamientos de ictioplancton determinada por la batimetría, refleja la distribución de los adultos. Por otro lado, las variaciones en la estructura de la comunidad de larvas a lo largo de la costa responden a cambios en la amplitud de la plataforma. A partir de la distribución observada en los dos poblamientos, se sugiere la presencia de un frente halino en la zona, que limita la dispersión de las larvas según un eje costa - mar abierto (Sabatés, 1990).Instituto Español de Oceanografí

Discrimination between magnetic shear and toroidal electric field effects in TJ-II plasmas

The response of TJ-II plasmas to an induced toroidal electric field, Eǿ , was studied in past experiments with the aid of Ohmic inducted current. It was found that positive induced plasma current, Ip, degrades the confinement while negative Ip improves it. Candidates to provide a physical explanation are Eǿ itself and the plasma current via magnetic shear modification. A movable mirror in an electron Cyclotron Heating line of TJ-II permits varying the refraction index of the heating wave, N||, thus allowing for non inductive electron cyclotron current drive (ECCD) up to Ip ≈ ±1 kA. Comparing discharges without and with ECCD (changing shear but not Eǿ ) but sharing the same transformer action (changing both shear and Eǿ ), magnetic shear and electric field effects can be discriminated in time. It has been found that plasma response with ECCD is delayed respect to the transformer switch-on time, clearly pointing to shear effects. Effects related to Eǿ alone, if they exist, are weaker

Simulations of Alfvénic modes in TJ-II Stellarator

Alfvénic modes are one of the subclass of instabilities prevalent in burning plasmas due to interaction of energetic particles with background plasma. In this paper we investigate the properties of these modes with 3D simulations using modeling tools STELLGAP [1] and AE3D [2] of Neutral Beam Injection (NBI) heated H-plasmas in TJ-II low-magnetic-shear flexible heliac (B0 = 0.95 T, = 1.5 m, = 0.22 m). These simulations focus on modelling the experimental observations [3] for prominent modes in TJ-II plasmas. Our simulations show consistency in frequency and radial location with the measured Alfvén Eigenmodes [3]. These simulations are performed for chirping and steady modes in TJ-II discharge # 29839 at t = 1150 and 1160ms respectively

Towed sensors and hydrodynamic model evidence the need to include submarine in coastal lagoons water balance, the Mar Menor example (SE Spain).

The use of radionuclide tracers to determine the submarine groundwater discharges has been used widely but in areas highly anthropized as the Mar Menor surface water tributaries can carry high concentration of Radon, making very difficult to distinguish the radionuclide origin. In this paper a combined approach was applied in the Mar Menor, a towed system was designed to enable the continuous measurement of Radon and Nitrate and a hydrodynamic model was used to establish the influence areas of the surface discharge to the lagoon. The areas were Radon was detected and was out from the area located with the model could be establish as a submarine groundwater discharge point.Peer Reviewe

Calculation of the bootstrap current profile for the TJ-II stellarator

Calculations of the bootstrap current for the TJ-II stellarator are presented. DKES and NEO-MC codes are employed; the latter has allowed, for the first time, the precise computation of the bootstrap transport coefficient in the long mean free path regime of this device. The low error bars allow a precise convolution of the monoenergetic coefficients, which is confirmed by error analysis. The radial profile of the bootstrap current is presented for the first time for the 100_44_64 configuration of TJ-II for three different collisionality regimes. The bootstrap coefficient is then compared to that of other configurations of TJ-II regularly operated. The results show qualitative agreement with toroidal current measurements; precise comparison with real discharges is ongoing

Study of the neoclassical radial electric field of the TJ-II flexible heliac

Calculations of the monoenergetic radial diffusion coefficients are presented for several configurations of the TJ-II stellarator usually explored in operation. The neoclassical radial fluxes and the ambipolar electric field for the standard configuration are then studied for three different collisionality regimes, obtaining precise results in all cases

Observations of sustained phase shifted magnetic islands from externally imposed m/n = 1/1 RMP in LHD

New observations in the Large Helical Device (LHD) show that the magnetic islands externally imposed by m/n = 1/1 resonant magnetic perturbation (RMP) can be maintained in an intermediate state with a finite phase shift away from the value present in vacuum. Given the previous experimental observation that the saturated magnetic islands show either growth or healing, the intermediate states are realized in the “healing region” in the beta and collisionality space, which implies that a parameter other than beta and collisionality should exist in order to determine the island state. Theories based on the competition between electromagnetic torques and poloidal flow-induced viscous torques provide a prediction for the intermediate state. These two types of torques might be balanced to realize the steadily maintained intermediate state whereas the islands are placed in the growth state or healing state in the case in which the balance is broken. The experimental observation shows that there is a possibility for the magnetic island phase to deviate from its designed position. If the parameters are controlled properly, it is possible to control the phase of the magnetic island, which may permit continued utilization of the island divertor concept

Molecular basis of caspase-1 polymerization and its inhibition by a new capping mechanism

Inflammasomes are cytosolic caspase-1-activation complexes that sense intrinsic and extrinsic danger signals, and trigger inflammatory responses and pyroptotic cell death. Homotypic interactions among Pyrin domains and caspase recruitment domains (CARDs) in inflammasome-complex components mediate oligomerization into filamentous assemblies. Several cytosolic proteins consisting of only interaction domains exert inhibitory effects on inflammasome assembly. In this study, we determined the structure of the human caspase-1 CARD domain (caspase-1[superscript CARD]) filament by cryo-electron microscopy and investigated the biophysical properties of two caspase-1-like CARD-only proteins: human inhibitor of CARD (INCA or CARD17) and ICEBERG (CARD18). Our results reveal that INCA caps caspase-1 filaments, thereby exerting potent inhibition with low-nanomolar K[subscript i] on caspase-1[superscript CARD] polymerization in vitro and inflammasome activation in cells. Whereas caspase-1[superscript CARD] uses six complementary surfaces of three types for filament assembly, INCA is defective in two of the six interfaces and thus terminates the caspase-1 filament