On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

PLASMA CONDITIONS FOR OPTIMUM GAIN IN RESONANT PHOTOEXCITATION OF STRONTIUM NEON-LIKE IONS BY ALUMINIUM RADIATION

On étudie sur le plan théorique et expérimental la photoexcitation résonnante des ions néonoides du strontium par le rayonnement des ions hydrogénoides de l'aluminium. Les conditions de plasma favorisant la photoexcitation sont définies par des études en spectroscopie X et XUV. La conception des cibles est réalisée avec l'aide d'une étude de l'ablation de couches de strontium en fonction des conditions laser. L'absorption du rayonnement de l'aluminium par le strontium est démontrée dans une expérience à deux plasmas.Resonant photoexcitation of strontium neon-like ions by the radiation of aluminium hydrogen-like ions is studied theoretically and experimentally in laser-created plasmas. X-ray and XUV spectroscopy are used as tools to define plasma conditions where photo-pumping is efficient. The design of targets is completed by ablation studies of strontium layers under various experimental conditions. Absorption spectroscopy in a two plasma experiment demonstrates the potential usefulness of quasi-resonant photoexcitation in neon-like X-ray amplifiers

DIAGNOSTICS OF GOLD LASER PLASMAS

Dans le but d'étudier un schéma de laser X dans les nickeloïdes, on a besoin d'un modèle pour déterminer les paramètres qui décrivent les plasmas d'ions lourds fortement ionisés. Le sujet de ce travail est d'étudier les plasmas d'or créés par laser et de comparer les résultats expérimentaux aux prédictions d'un modele collisionnel-radiatif dans les nickeloïdes. La température et la densité électronique sont mesurées à partir des raies d'emission d'un traceur d'aluminium, et sont comparées aux valeurs obtenues avec le modèle collisionnel-radiatif pour un plasma d'or pur. Les résultats montrent que l'on peut estimer la température et la densité électronique dans un plasma d'or pur.In order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-2 plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma

Nucleolin interacts with US11 protein of herpes simplex virus 1 and is involved in its trafficking

Herpes simplex virus type 1 (HSV-1) infection induces profound nucleolar modifications at the functional and organizational levels, including nucleolar invasion by several viral proteins. One of these proteins is US11, which exhibits several different functions and displays both cytoplasmic localization and clear nucleolar localization very similar to that of the major multifunctional nucleolar protein nucleolin. To determine whether US11 interacts with nucleolin, we purified US11 protein partners by coimmunoprecipitations using a tagged protein, Flag-US11. From extracts of cells expressing Flag-US11 protein, we copurified a protein of about 100 kDa that was further identified as nucleolin. In vitro studies have demonstrated that nucleolin interacts with US11 and that the C-terminal domain of US11, which is required for US11 nucleolar accumulation, is sufficient for interaction with nucleolin. This association was confirmed in HSV-1-infected cells. We found an increase in the nucleolar accumulation of US11 in nucleolin-depleted cells, thereby revealing that nucleolin could play a role in US11 nucleocytoplasmic trafficking through one-way directional transport out of the nucleolus. Since nucleolin is required for HSV-1 nuclear egress, the interaction of US11 with nucleolin may participate in the outcome of infection