80 research outputs found

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    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

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    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

    Aspectos da evolução e da geografia do gênero Philodendron Schott (Araceae)

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    O gênero Philodendron se divide em três subgêneros, cada um com distintos padrões de morfologia, anatomia e distribuição. Em análise filogenética, o subgêneiro Meconostigma, o único com centro de especiação no sudeste do Brasil, mostra-se bastante apomórfico, ainda que cladisticamente primitivo no gênero. Análises fenéticas mostram que o gênero se constitue um taxon distinto, apesar de não ter um só caráter definitivo. Mostram também que feneticamente, Philodendron está mais perto de certos gêneros da África ocidental (Culcasia, Cercestis, Rhektophyllum) do que dos gêneros principalmente asiáticos com os quais está ligado pela classificação tradicional. A morfologia do gineceu varia muito no subgênero Meconostigma, com as formas mais simples ocorrendo no sudeste do Brasil e as mais elaboradas na Amazônia. Comparação com o "grupo de fora" indica que as formas mais simples são primitivas no subgênero, apontanto as espécies principalmente rupícolas, P. adamantinum Schott e P. leal-costae Mayo & G.M.Barroso, como as de gineceus mais primitivos. Com base na morfologia do gineceu, poderia ser sugerido que o subgênero evoluiu em princípio na parte oriental do Brasil, como um grupo adaptado aos habitats abertos, e que na bacia amazônica ele chegou somente mais tarde. Os dois outros subgêneros, Philodendron e Pteromischum, surgiram posteriormente, principalmente como epífitas de florestas úmidas, e se mostram hoje mais diversos no nordeste da América do Sul<br>The genus Philodendron can be divided into three subgenera which are very distinct in vegetative and floral morphology, floral anatomy and distribution. Phylogenetic and phenetic analysis of floral characters indicate that subgenus Meconostigma, which unlike subgenera Philodendron and Pteromischum has a predominantly southeastern range in South America, is highly apomorphic but cladistically primitive in the genus. Phenetic analyses show that the genus can be viewed as distinct, although no definitive diagnostic character is known to exist. These analyses also show that Philodendron is phenetically closer to certain west African genera (Culcasia, Cercestis, Rhektophyllum) than to the mainly Asiatic genera with it has been traditionally associated. Gynoecial morphology in subgen. Meconostigma varies considerably, with simpler forms predominating in southeastern Brazil, and the most elaborate in Amazonia. Outgroup comparison suggests that the simpler types are more primitive and indicates that the rupicolous species P. adamantinum Schott and P. leal-costae Mayo & G.M.Barroso possess the most primitive gynoecial type. Based on gynoecial morphology it is suggested that the subgenus evolved initially in eastern Brazil as a group adapted to open habitats, arriving only later in the Amazon basin. The other two subgenera, Philodendron aud Pteromischum, arose later, as epiphytes of humid forestes and today are most diverse in the northeast of South Americ
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