188 research outputs found
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
Tungsten and CFC Degradation Under Combined High Cylce Transient and Steady State Heat Loads
Advances of Nanoscaled Additives on the Thermomechanical Performace of Al2O3-C and MgO Refractories
Charakteryzacja mikrostuktury stopów na osnowie wolframu przeznaczonych do zastosowań w procesach syntezy jądrowej
The microstructure of two tungsten based alloys (W-1.1%TiC and W-1.7% TiC) was characterized using light microscopy, analytical electron microscopy and electron tomography. These alloys represent a class of W based dispersion strengthened alloys with TiC used as strengthening particles. Addition of TiC leads to improved creep resistance and tensile strength of the W based alloys. The results show that the W-1.7%TiC alloy exhibits large scatter in grain size, much higher porosity and contains also Ti-O particles. The W-1.1%TiC alloy has fine grained microstructure with uniformly distributed fine TiC particles within the matrix and low porosity. As a result of the different microstructure, the W-1.1%TiC alloy exhibits better mechanical properties, when compared to the W-1.7%TiC alloy.W pracy przedstawiono wyniki badań mikrostruktury dwóch stopów wolframu: W-1.1%TiC oraz W-1.7%TiC. Badania przeprowadzono z wykorzystaniem technik mikroskopii świetlnej, analitycznej mikroskopii elektronowej oraz tomografii elektronowej. Przebadane stopy reprezentują grupę stopów wolframu umacnianych dyspersyjnie cząstkami TiC. Dodatek TiC poprawia odporność na pełzanie oraz wytrzymałość tych stopów. Badania wykonane dla stopu W-1.7%TiC wskazują na duże różnice w wielkości ziarna, duża porowatość oraz występowanie cząstek TiO. Stop W-1.1TiC posiada drobnoziarnistą strukturę, niską porowatość oraz równomiernie rozmieszczone cząstki TiC w osnowie W. Stop W-1.1%TiC charakteryzuje się znacznie lepszymi właściwościami mechanicznymi niż stop W-1.7%TiC
- …