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

Correlating Electrochemical Behavior and Speciation in Neodymium Ionic Liquid Electrolyte Mixtures in the Presence of Water

Publisher Copyright: Copyright © 2020 American Chemical Society.Electrodeposition of rare earth metals at moderate temperature as a means to recover these critical materials from spent magnets or electric motors would be a major breakthrough to close the loop using a sustainable approach. This work highlights that neodymium electrodeposition in a phosphonium-based ionic liquid requires the presence of water in order to achieve a continuous layer of metal deposition. Herein, we describe that the nature of the Nd3+ solvation sphere being composed of both bis(trifluoromethylsulfonyl)imide (TFSI) and water determines neodymium deposition and that this process is not entirely dependent on the physicochemical properties of the electrolyte. The importance of the concentration of neodymium salt for the electrodeposition process has also been investigated, showing that 0.1 mol/kg Nd(TFSI)3/[P66614][TFSI] with 0.4 wt % water is the most promising electrolyte investigated, giving a favorable Nd3+ reduction process and better quality deposits.This work was partly funded by the Institute for Frontier Materials (Deakin University) Research program to lead innovative and transformative research in redesigning materials for a circular economy. This work was supported by a grant received from Basque Government (grant number KK-2016/00095 assigned to the project LISOL-Soluciones basadas en liquidos iónicos para diversificar las oportunidades de la industria vasca) and Deakin University (IFM Student Travel Award). M.F. acknowledges the Ikerbasque, Basque Foundation for Science. We also thank Prof. Patrik Johansson for useful discussion of the FTIR spectra.Peer reviewe

Water-Facilitated Electrodeposition of Neodymium in a Phosphonium-Based Ionic Liquid

Rare-earth metals are considered critical metals due to their extensive use in energy-related applications such as wind turbines and nickel–metal hybrid batteries found in hybrid electrical vehicles. A key drawback of the current processing methods includes the generation of large amounts of toxic and radioactive waste. Thus the efficient recovery of these valuable metals as well as cleaner processing methods are becoming increasingly important. Here we report on a clean electrochemical route for neodymium (Nd) recovery from [P6,6,6,14][TFSI], trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide which is amplified three times by the presence of water, as evidenced by the cathodic current density and thicker deposits. The role of Nd salt concentrations and water content as an additive in the electrochemistry of Nd3+ in [P6,6,6,14][TFSI] has been studied. The presence of metallic neodymium in the deposits has been confirmed by X-ray photoelectron spectroscopy.ELKARTEK 2016, KK-2016/00095, LISO

Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall

This paper reports the impact on confinement and power load of the high-shape 2.5MA ELMy H-mode scenario at JET of a change from an all carbon plasma facing components to an all metal wall. In preparation to this change, systematic studies of power load reduction and impact on confinement as a result of fuelling in combination with nitrogen seeding were carried out in JET-C and are compared to their counterpart in JET with a metallic wall. An unexpected and significant change is reported on the decrease of the pedestal confinement but is partially recovered with the injection of nitrogen.Comment: 30 pages, 16 figure