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

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Isotope effects on intrinsic rotation in hydrogen, deuterium and tritium plasmas

The isotope effect on intrinsic rotation was studied at the Joint European Torus (JET) tokamak. With the unique capability of JET to operate with tritium (T), for the first time, experiments in hydrogen (H), deuterium (D) and T in Ohmic plasmas were compared. Two rotation reversals per isotope type are observed in plasma density scans spanning the linear and the saturated Ohmic confinement regimes. A clear isotope mass dependence is observed at the higher densities. The magnitude of the core rotation was found to depend on isotope mass, with stronger co-current rotation observed in H. Change on intrinsic rotation characteristics coexist with a stronger thermal energy confinement in T

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

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

Effectiveness and safety of valsartan in children aged 6 to 16 years with hypertension

The effectiveness and safety of valsartan have not been assessed in hypertensive children. Therefore, hypertensive patients aged 6 to 16 years (n=261) were randomized to receive weight‐stratified low‐ (10/20 mg), medium‐ (40/80 mg), or high‐dose (80/160 mg) valsartan for 2 weeks. After 2 weeks, patients were randomized to a 2‐week placebo‐controlled withdrawal phase. Dose‐dependent reductions in sitting systolic blood pressure (SSBP) and sitting diastolic blood pressure (SDBP) were observed after 2 weeks (low dose, −7.9/−4.6 mm Hg; medium dose, −9.6/−5.8 mm Hg; high dose, −11.5/−7.4 mm Hg [P<.0001 for all groups]). During the withdrawal phase, SSBP and SDBP were both lower in the pooled valsartan group than in the pooled placebo group (SSBP, −2.7 mm Hg [P=.0368]; SDBP, −3.0 mm Hg [P=.0047]). Similar efficacy was observed in all subgroups. Valsartan was well tolerated and headache was the most commonly observed adverse event during both the double‐blind and 52‐week open‐label phases. J Clin Hypertens (Greenwich). 2011;13:357–365. ©2011 Wiley Periodicals, Inc

Comportamento espectral dos solos na paisagem a partir de dados coletados por sensores terrestre e orbital Spectral response of soils in the landscape based on terrestrial and orbital data acquisition levels

Parte da variabilidade dos índices de produção agrícola está associada com as características do solo e da paisagem. Dessa forma, práticas de manejo, como a adubação, devem levar em consideração esta variabilidade. O sensoriamento remoto é uma ferramenta que pode fornecer, de maneira rápida, informações para o manejo do solo, pois relaciona a radiação eletromagnética com os atributos do solo. Assim, este trabalho teve como objetivo avaliar o comportamento espectral, em dois níveis de aquisição de dados (terrestre e orbital), de diferentes classes de solos ao longo de toposseqüências na região de São Carlos e Ibaté, SP. Para isso, amostras de terra georreferenciadas foram coletadas em 319 pontos, em três profundidades. Em seguida, obtiveram-se os dados radiométricos em laboratório, na faixa espectral entre 450 e 2.500 nm. Os mesmos locais amostrados na camada superficial, no campo, foram avaliados na imagem de satélite. A partir dos resultados obtidos, pode-se concluir que: (a) teores de areia grossa, argila e matéria orgânica, e cor tiveram relação com a reflectância dos solos; (b) ao longo das vertentes ocorrem variações nos dados espectrais dos solos; e (c) solos da mesma ordem taxonômica, porém com classes texturais diferentes, apresentam diferentes comportamentos espectrais, podendo ser discriminados por sensoriamento remoto.<br>Part of agricultural production index variability is associated with soil and landscape characteristics. Management practices such as fertilizer application should therefore take the soil spatial variability into account. Remote sensing is a tool that can provide faster information for soil management because it relates electromagnetic radiation with soil attributes. Thus, this study aimed at evaluating the spectral response, at two data acquisition levels (terrestrial and orbital), of different soil classes across toposequences in the region of São Carlos and Ibaté, SP. For this purpose, georeferenced soil samples were collected at 319 points and three depths, and radiometric data were obtained in the laboratory using a spectroradiometer (spectral band 450-2500 nm). The same points sampled in the field in the surface layer were evaluated by the satellite image (ASTER). Based on the results it was possible to conclude that (a) coarse sand, clay, organic matter and color were strongly related with soil reflectance; (b) soil spectral data vary along the declivities; (c) soils of the same taxonomy order, but of different clay classes, have different spectral performances and can be discriminated by remote sensing

Efeito de esterco bovino sobre os rendimentos de espigas verdes e de grãos de milho The effect of cattle manure on yield of green corn ears and maize grains

Avaliaram-se os efeitos de doses de esterco bovino (0; 8; 16; 24; 32 e 40 t ha-1) sobre os rendimentos de espigas verdes e de grãos de duas cultivares de milho (Centralmex e AG-9012). O trabalho foi realizado em Mossoró (RN), de setembro a dezembro/99, com irrigação por aspersão. Utilizou-se esquema de parcelas subdivididas no delineamento de blocos completos casualizados com três repetições. As doses de esterco foram aplicadas às parcelas e as cultivares, às subparcelas. O rendimento de milho verde foi avaliado pelo número e peso totais de espigas verdes empalhadas e pelo número e peso de espigas comercializáveis, empalhadas e despalhadas. O rendimento de grãos foi avaliado pelo peso dos grãos corrigido para 15,5% de umidade. Análises do solo, realizadas aos 120 dias após o plantio, constataram que o esterco aumentou a retenção e a disponibilidade de água e os teores de fósforo, potássio e sódio, na camada do solo de 20-40 cm, mas não influenciou o pH e os teores de cálcio, soma de bases e de matéria orgânica. Tanto o rendimento de espigas verdes como o rendimento de grãos aumentaram com o aumento da dose de esterco, exceto o número e o peso totais de espigas verdes da cultivar Centralmex. A cultivar AG-9012 foi superior à cultivar Centralmex quanto aos rendimentos de espigas verdes e de grãos. A receita líquida, calculada com a comercialização de espigas empalhadas comercializáveis, foi maior na ausência de esterco para a cultivar AG-9012 e com a aplicação de 8 t ha-1para a Centralmex.<br>The effect of different levels of cattle manure (0; 8; 16; 24; 32 and 40 t ha-1) on yield of green corn ears and grains of two maize cultivars was evaluated (Centralmex and AG-9012). The study was carried out at Mossoró, Rio Grande do Norte State, Brazil, from September to Dezember 1999 using sprinkler irrigation. The experimental design was complete random blocks arranged in splitplot with three replications. The manure was applied to main plots and cultivars in the subplots. The green corn yield was evaluated by total number and weight of green ears with husk and by marketables ears, with husk and without husk. The grain yield was evaluated by grain weight corrected for 15,5% humidity. The soil analysis, carried out 120 days after planting, indicated that the manure increased the water retention, water availability and the potassium, sodium and phosphorus contents, however, did not influence pH, calcium, sum of bases and organic matter contents. The manure levels x cultivars interaction was significant for number of marketable ears with husk only. All evaluated traits increased with the increase of manure levels. The cultivar AG-9012 was superior to the cultivar Centralmex for the evaluated traits. The net income, obtained with the sale of marketable ears with husk, was higher when no manure was applied for AG-9012. For the cultivar Centralmex, the net income was higher with 8 t ha-1 cattle manure application

Isotope effects on intrinsic rotation in hydrogen, deuterium and tritium plasmas

Abstract The isotope effect on intrinsic rotation was studied at the Joint European Torus (JET) tokamak. With the unique capability of JET to operate with tritium (T), for the first time, experiments in hydrogen (H), deuterium (D) and T in Ohmic plasmas were compared. Two rotation reversals per isotope type are observed in plasma density scans spanning the linear and the saturated Ohmic confinement regimes. A clear isotope mass dependence is observed at the higher densities. The magnitude of the core rotation was found to depend on isotope mass, with stronger co-current rotation observed in H. Change on intrinsic rotation characteristics coexist with a stronger thermal energy confinement in T.</jats:p