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

The molecular taphonomy of Carboniferous animal and plant cuticles from North America

Analyses of identifiable organic fossil remains of animals and plants have considerable potential to resolve conflicting models of organic matter diagenesis and kerogen formation (e.g. selective preservation versus random polymerization). Fossil cuticles of arthropods (scorpion, eurypterid) and plants (cordaite, pteridosperm) from Upper Carboniferous strata of Lone Star Lake, Kansas, USA and Joggins, Nova Scotia, Canada were analysed by pyrolysis-gas chromatography/mass spectrometry and examined by electron microscopy. Recent Pandinus (scorpion) and Araucaria (conifer) provided a basis for comparison. Pyrolysis of Recent dewaxed scorpion cuticle yielded products derived from chitin and proteins. These products were absent in the fossil arthropod cuticles, however, which yielded an homologous series of alkanes and alkenes, together with phenolic and other aromatic constituents. Recent dewaxed plant cuticle yielded fatty acids, phenols and carbohydrate-derived compounds indicative of cutin polyester and associated lignocellulose. The pyrolysates of the fossil plant cuticles, on the other hand, were dominated by alkane-alkene doublets, with minor phenolic and other benzenoid components. There is no evidence that the preservation of these cuticles as particulate organic matter in kerogen is simply a result of selective preservation. Nonetheless, the chemistry and morphology remain characteristic of a particular taxon, hereby eliminating the possibility of incorporation of randomly repolymerized materials or the transfer of material between plant and animal residues. The aliphatic moieties in the fossil cuticles are thought to be the result of polymerization of the associated epicuticular, cuticular and/or tissue lipids during diagenesis