[en] Full text: The impact of ELM activity and density limit disruptions on the plasma density as well as the use of reflectometry for plasma position and shape control are discussed here. Fast density measurements allow the definition of three characteristic phases of the ELM: precursor, collapse and recovery. At the precursor phase low frequency oscillations starting approximately 3 ms prior to the ELM collapse are observed in the density profiles. Fluctuation measurements show a continuous rise of the broadband fluctuations prior to the ELM collapse. In the collapse phase the crash of the density profile is observed. In the recovery phase, the density profile starts to recover its pre-ELM shape. A comparison between HFS and LFS density behaviour shows a delay on the density collapse, comparable to the ion parallel transport time indicating a ballooning character of the ELM. For a set of ASDEX Upgrade ELMy H-modes, where plasma parameters such as plasma current, plasma density, triangularity and input power were varied, the radial velocity, ELM particle losses and affected depth, density pedestal width and edge density gradient are determined and its dependence with the plasma parameters determined. A comparison between intrinsic and pellet triggered ELMs shows no relevant differences suggesting that the triggering mechanism for both ELM type cannot be distinguished by the density profile dynamics or the density fluctuations. The changes observed on the density profiles during density limit disruptions support the observation that the erosion of the temperature is due to convection and not by stochastization. The information about the density profiles also provides a powerful tool for plasma position and shape control, as proposed for ITER to complement the magnetic measurements. Provided that the density is constant within the magnetic flux surfaces, a scaling factor between the line average density and the density at the separatrix can be used to estimate the density at the separatrix. The separatrix position can then be found from the measured density profiles. Software tools developed to quantify the errors involved in reflectometry gap evolution were used in ASDEX Upgrade ELMy H-mode discharges. The estimated position of the separatrix is found within 1 cm of accuracy when compared to similar magnetic data.(author)

[en] Operation with a Be/W wall at JET (JET-ILW) has an impact on scenario development and energy confinement with respect to the carbon wall (JET-C). The main differences observed were (1) strong accumulation of W in the plasma core and (2) the need to mitigate the divertor target temperature to avoid W sputtering by Be and other low Z impurities and (3) a decrease of plasma energy confinement. A major difference is observed on the pedestal pressure, namely a reduction of the pedestal temperature which, due to profile stiffness the plasma core temperature is also reduced leading to a degradation of the global confinement. This effect is more pronounced in low β _N scenarios. At high β _N, the impact of the wall on the plasma energy confinement is mitigated by the weaker plasma energy degradation with power relative to the IPB98(y, 2) scaling calculated empirically for a CFC first wall. The smaller tolerable impurity concentration for tungsten (<10"−"5) compared to that of carbon requires the use of electron heating methods to prevent W accumulation in the plasma core region as well as gas puffing to avoid W entering the plasma core by ELM flushing and reduction of the W source by decreasing the target temperature. W source and the target temperature can also be controlled by impurity seeding. Nitrogen and Neon have been used and with both gases the reduction of the W source and the target temperature is observed. Whilst more experiments with Neon are necessary to assess its impact on energy confinement, a partial increase of plasma energy confinement is observed with Nitrogen, through the increase of edge temperature. The challenge for scenario development at JET is to extend the pulse length curtailed by its transient behavior (W accumulation or MHD), but more importantly by the divertor target temperature limits. Re-optimisation of the scenarios to mitigate the effect of the change of wall materials maintaining high global energy confinement similar to JET-C is underway and JET has successfully achieved H _9_8_(_y_,_2_)  =  1 for plasma currents up to 2.5 MA at moderate β _N. (paper)

[en] Microwave reflectometry is a diagnostic well suited to measure the plasma density profile in large fusion devices. The possibility to make reflectometry measurements with unfavourable propagation of the incident microwaves is especially important in devices where significant modifications of the flux surfaces are expected, as will be the case of ITER. The sensitivity of reflectometry to D-shaped and circular plasma configurations was studied in ASDEX Upgrade. Ray tracing was used to model the experiments and to determine the limits for reflectometry measurements. (orig.)

[en] Herein we propose a data processing method to analyse broadband reflectometry signals based on the Wigner-Ville distribution (WVD). The method offers the advantage of good localization of the reflectometry signal energy in the time-frequency domain. Simulations are presented to test the ability of this technique to follow the average beat frequency that is the relevant quantity to invert the plasma profile. The method is compared with the short-time Fourier transform (STFT) analysis both for simulated and for ASDEX Upgrade plasmas. It is shown that the WVD has potential advantages for the routine evaluation of density profiles. The method can also be useful to study fluctuations, namely when abrupt changes of turbulence occur at the L-H transition. (orig.)

No abstract available

[en] In the framework of the CRP on “Radiation treatment of wastewater for reuse with particular focus on wastewaters containing organic pollutants” Portuguese team is been developed studies on the implementation of ionizing radiation technology as a complementary treatment for industrial effluents and increase the added value of these wastewaters. Based on these assumptions, preliminary studies of the gamma radiation effects on the antioxidant compounds present in cork cooking water were carried out. Radiation studies were performed by using radiation between 20 and 50 kGy at 0.4 kGy/h and 2.4 kGy/h. The radiation effects on organic matter content were evaluated by Chemical Oxygen Demand (COD). The antioxidant activity was measured by Ferric Reducing Power (FRAP) assay. The total phenolic content was studied by Folin-Ciocalteau method. Results point out that gamma radiation increases both the amount of phenolic compounds and antioxidant capacity of cork cooking water. By the other hand, the radiolytic degradation by ionizing radiation of gallic acid and esculetin as models for recalcitrants were studied. The objective of this study was to find out if radiolytic degradation, followed by microbial degradation could increase the treatment efficiency. A natural cork wastewater bacterium was selected from the irradiated wastewater at 9 kGy. The applied methodology was based on the evaluation of growth kinetics of the selected bacteria by turbidimetry and colony forming units, in minimal salt medium with non-irradiated and irradiated phenolic as substrate. The overall obtained results highlights the potential of this technology for increase the add value of cork waters and raised some issues to explain by new methodological setup on biodegradation studies. (author)

No abstract available

[en] Today, increased concerns regarding the safeguarding of heritage result in constant evolution of the conservation and restoration fields as new challenges arise. Besides the deterioration that occurs with the passing of time, most of our cultural and artistic heritage can be damaged by environmental factors as well as by organisms and microorganisms that attack and may induce aesthetic changes. Microbial deterioration is related to environmental conditions and also to the physicochemical properties of the objects’ constituent materials. Microorganisms can cause alterations to material surfaces through a variety of mechanisms, including biofilm formation, chemical reactions with the material, physical penetration into the substrate and production of pigments. To diagnose biodeterioration processes and design effective biocontrol measures, the microbial communities and the material need to be investigated.

[en] The primary objective of the JET ITER-like wall project is to install a beryllium main wall and a tungsten divertor. For beryllium, melting and thermal stress limit the maximum power density which can be tolerated in operation. The tile design has to allow routine plasma operation for ITER relevant scenarios, i.e., q₉₅f ∼ [2.3-10] with high power input (P_in ≤ 30 MW) for pulse lengths of ∼10 s. This paper focuses on the power handling studies of the beryllium tiles for the outer poloidal limiters and ICRH horizontal protections, and the optimization of their design to achieve the operational goal described above

[en] The measurement of electron density in the JET pumped divertor by conventional reflectometry techniques is difficult because of poor access to the divertor region, unfavourable plasma geometry and the small plasma size. This paper presents a new reflectometer diagnostic which can operate in the difficult conditions of the pumped divertor. It is a 'comb' reflectometer in which a number of microwave signals with different frequencies are launched simultaneously into the plasma, and the peak electron density along the sightline is estimated by determining which signals are transmitted and which are reflected. The design and operating principles of the diagnostic are described, and preliminary results illustrating its performance are presented. (Author)