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)

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

local buzz, global pipelines and the process of knowledge creation

The version of record [Bathelt, H., Malmberg, A., & Maskell, P. (2004). Clusters and knowledge: Local buzz, global pipelines and the process of knowledge creation. Progress in Human Geography, 28(1), 31-56.] is available online at: http://phg.sagepub.com/content/28/1/31 [doi: 10.1191/0309132504ph469oa]The paper is concerned with spatial clustering of economic activity and its relation to the spatiality of knowledge creation in interactive learning processes. It questions the view that tacit knowledge transfer is confined to local milieus whereas codified knowledge may roam the globe almost frictionlessly. The paper highlights the conditions under which both tacit and codified knowledge can be exchanged locally and globally. A distinction is made between, on the one hand, the learning processes taking place among actors embedded in a community by just being there dubbed buzz and, on the other, the knowledge attained by investing in building channels of communication called pipelines to selected providers located outside the local milieu. It is argued that the co-existence of high levels of buzz and many pipelines may provide firms located in outward-looking and lively clusters with a string of particular advantages not available to outsiders. Finally, some policy implications, stemming from this argument, are identified

Uniaxial Stress Method for Delicate Crystals : Application to Shubnikov-de Haas and Superconductivity Studies in Organic Conductors

Contains fulltext : 29012.pdf (publisher's version ) (Open Access

Uniaxial-Stress Study of the Magnetotransport Properties of the Quasi-two Dimensional Organic Conductor Alpha-(BEDT-TTF)(2)KHg(SCN)(4)

Contains fulltext : 29010.pdf (publisher's version ) (Open Access

Intra-union flexibility of non-ETS emission reduction obligations in the European Union

The EU proposal on greenhouse gas emission reduction has 28 targets for 2020: an EU-wide one for CO2 emissions covered by the European Trading System (ETS), and one target for non-ETS emissions per Member State. Implementation is more expensive than needed. I consider three alternative proposals to reduce costs. In the Irish proposal, Member States can purchase ETS permits to offset excess non-ETS emissions. In the Polish proposal, Member States can sell excess non-ETS emissions in the ETS. In the Swedish proposal, Member States can trade their non-ETS allocations. I compare these alternatives to the default policy (no flexibility outside the ETS) and the cost-effective solution (full flexibility). I calibrate a simple model to the results of the EU impact assessment, which did not disclose all details and made odd assumptions. The non-ETS allocation exceeds the projected emissions for three Member States. The alternative flexibility mechanisms would be used to only a limited extent, but would cut the costs of meeting the target. The Swedish and Polish proposals come closest to the cost-effective solution because of the hot air. The Irish proposal performs best if there are negative surprises in either abatement costs or emissions. The Swedish proposal will become policy