Comparison of H-mode plasmas in JET-ILW and JET-C with and without nitrogen seeding

In high confinement mode, highly shaped plasmas with edge localized modes in JET, and for heating power of 15-17 MW, the edge fluid code EDGE2D-EIRENE predicts transition to detachment assisted by nitrogen at the low field side (LFS) target when more than 50% of the power crossing the separatrix between ELMs is radiated in the divertor chamber, i.e. ∼4 MW. This is observed both in the ITER-like wall (JET-ILW) and in the carbon wall (JET-C) configurations and is consistent with experimental observations within their uncertainty. In these conditions, peak heat fluxes below 1 MW m-2 are measured at the LFS target and predicted for both wall configurations. When the JET-C configuration is replaced with the JET-ILW, a factor of two reduction in the divertor radiated power and 25-50% increase in the peak and total power deposited to the LFS divertor plate is predicted by EDGE2D-EIRENE for unseeded plasmas similar to experimental observations. At the detachment threshold, EDGE2D-EIRENE shows that nitrogen radiates more than 80% of the total divertor radiation in JET-ILW with beryllium contributing less than a few %. With JET-C, nitrogen radiates more than 70% with carbon providing less than 20% of the total radiation. Therefore, the lower intrinsic divertor radiation with JET-ILW is compensated by stronger nitrogen radiation contribution in simulations leading to detachment at similar total divertor radiation fractions. 20-100% higher deuterium molecular fraction in the divertor recycling fluxes is predicted with light JET-C materials when compared to heavy tungsten. EDGE2D-EIRENE simulations indicate that the stronger molecular contribution can reduce the divertor peak power deposition in high recycling conditions by 10-20% due to enhanced power dissipation by molecular interaction

Safety of intravenous ferric carboxymaltose versus oral iron in patients with nondialysis-dependent CKD: an analysis of the 1-year FIND-CKD trial.

Background: The evidence base regarding the safety of intravenous (IV) iron therapy in patients with chronic kidney disease (CKD) is incomplete and largely based on small studies of relatively short duration. Methods: FIND-CKD (ClinicalTrials.gov number NCT00994318) was a 1-year, open-label, multicenter, prospective study of patients with nondialysis-dependent CKD, anemia and iron deficiency randomized (1:1:2) to IV ferric carboxymaltose (FCM), targeting higher (400-600 µg/L) or lower (100-200 µg/L) ferritin, or oral iron. A post hoc analysis of adverse event rates per 100 patient-years was performed to assess the safety of FCM versus oral iron over an extended period. Results: The safety population included 616 patients. The incidence of one or more adverse events was 91.0, 100.0 and 105.0 per 100 patient-years in the high ferritin FCM, low ferritin FCM and oral iron groups, respectively. The incidence of adverse events with a suspected relation to study drug was 15.9, 17.8 and 36.7 per 100 patient-years in the three groups; for serious adverse events, the incidence was 28.2, 27.9 and 24.3 per 100 patient-years. The incidence of cardiac disorders and infections was similar between groups. At least one ferritin level ≥800 µg/L occurred in 26.6% of high ferritin FCM patients, with no associated increase in adverse events. No patient with ferritin ≥800 µg/L discontinued the study drug due to adverse events. Estimated glomerular filtration rate remained the stable in all groups. Conclusions: These results further support the conclusion that correction of iron deficiency anemia with IV FCM is safe in patients with nondialysis-dependent CKD

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

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)

Main results of the first experimental campaign in the stellarator W7-X

A summary of the first operational phase (OP1.1) at the stellarator W7-X is given. The operational setup of heating and diagnostics as well the results of experiments are briefly described. Plasma parameters and confinement are better than expected: Te > 8 keV and Ti > 2 keV at ne ≈ 3×1019 m-3 yielding β0 ≈ 2.5 %. The results for ECR heating with X2-mode as well the ECCD are in good agreement with the theory predictions. The heating scenario with the O2-mode alone was successfully first time performed. Stellarator specific regime of core “electron root” confinement was obtained

Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X

In this paper, we present the design and commissioning results of the upgraded collective Thomson scattering diagnostic at the Wendelstein 7-X stellarator. The diagnostic has a new radiometer designed to operate between the second and third harmonics of the electron cyclotron emission from the plasma at 171–177 GHz, where the emission background has a minimum and is of order 10–100 eV. It allows us to receive the scattered electromagnetic field with a significantly improved signal-to-noise ratio and extends the set of possible scattering geometries compared to the case of the original instrument operated at 140 GHz. The elements of the diagnostic are a narrowband notch filter and a frequency stabilized probing gyrotron that will allow measuring scattered radiation spectra very close to the probing frequency. Here, we characterize the microwave components applied to the radiometer and demonstrate the performance of the complete system that was achieved during the latest experimental campaign, OP2.1