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

23rd IAEA Fusion Energy Conference: summary of sessions EX/C and ICC

An overview is given of recent experimental results in the areas of innovative confinement concepts, operational scenarios and confinement experiments as presented at the 2010 IAEA Fusion Energy Conference. Important new findings are presented from fusion devices worldwide, with a strong focus towards the scientific and technical issues associated with ITER and W7-X devices, presently under construction

The Intertemporal Mechanics of European Stock Price Momentum

Purpose: The purpose of this paper is to examine the relationship between a stock market's index returns and its subsequent firm-level momentum profits. This relationship is analysed for each of ten individual European stock markets between 1973 and 2010. Design/methodology/approach: Using firm-level data, intra-market momentum returns are analysed, using various ranking and holding period combinations. Standard t-tests as well as pooled and country-specific regressions are employed to determine the significance of the non-linear relationship between one-, two- and three-year index returns and subsequent momentum returns. Findings: Momentum returns following a bull market are positive for all ten stock markets; statistical significance is reached by nine of those ten. Per contrast, momentum returns following a bear market are insignificant for all ten stocks markets, and the average return is negative. Further, in all ten stock markets the momentum profits are lowest following the greatest drops in the index; this effect is significant in eight countries. These results are consistent with the behavioural theories on investors' overconfidence and undue self-attribution. Practical implications: The paper's findings suggest that investors should refrain from pursuing a momentum strategy in European stock markets shortly after a severe bear market. Originality/value: This is the first study to investigate the temporal dependence of firm-level momentum returns on preceding index movements in European stock markets. © Emerald Group Publishing Limited