3-D discrete dispersion relation, numerical stability, and accuracy of the hybrid FDTD model for cold magnetized toroidal plasma

The Finite-Difference Time-Domain (FDTD) method in cylindrical coordinates is used to describe electromagnetic wave propagation in a cold magnetized plasma. This enables us to study curvature effects in toroidal plasma. We derive the discrete dispersion relation of this FDTD scheme and compare it with the exact solution. The accuracy analysis of the proposed method is presented. We also provide a stability proof for nonmagnetized uniform plasma, in which case the stability condition is the vacuum Courant condition. For magnetized cold plasma we investigate the stability condition numerically using the von Neumann method. We present some numerical examples which reproduce the dispersion relation, wave field structure and steady state condition for typical plasma modes

Linearly polarised photon beams at ELSA and measurement of the beam asymmetry in pi^0-photoproduction off the proton

At the electron accelerator ELSA a linearly polarised tagged photon beam is produced by coherent bremsstrahlung off a diamond crystal. Orientation and energy range of the linear polarisation can be deliberately chosen by accurate positioning of the crystal with a goniometer. The degree of polarisation is determined by the form of the scattered electron spectrum. Good agreement between experiment and expectations on basis of the experimental conditions is obtained. Polarisation degrees of P = 40% are typically achieved at half of the primary electron energy. The determination of P is confirmed by measuring the beam asymmetry, \Sigma, in pi^0 photoproduction and a comparison of the results to independent measurements using laser backscattering.Comment: 9 pages, 10 figures, submitted to EPJ

Microhardness and Young's modulus of high burn-up UO2 fuel

Vickers microhardness (HV0.1) and Young's modulus (E) measurements of LWR UO2 fuel at burn-up > 60 GWd/tHM are presented. Their ratio HV0.1/E was found constant in the range 60-110 GWd/tHM. From the ratio and the microhardness values vs porosity, the Young's modulus dependence on porosity was derived and extended to the full radial profile, including the high burn-up structure (HBS). The dependence is well represented by a linear correlation. The data were compared to fuel performance codes correlations. A burn-up dependent factor was introduced in the Young's modulus expression. The modifications extend the experimental validation range of the TRANSURANUS correlation from unirradiated to irradiated UO2 and up to 20% porosity. First simulations of LWR fuel rod irradiations were performed in order to illustrate the impact on fuel performance. In the specific cases selected, the simulations suggest a limited effect of the Young's modulus decrease due to burn-up on integral fuel performance

Comparative analysis of electricity generating technologies with regards to environmental burdens

In the last couple of decades, there has been an increased awareness of the effects that electricity generation has on the environment through the emission of greenhouse gases and the depletion of natural resources. This realisation, coupled with an increased drive towards ensuring the sustainability of the energy supply system, has lead many, including the United Kingdom government to investigate the options for moving away from traditional fossil fuel-burning generation methods towards “lowcarbon” generators, such as renewables and nuclear power. Specifically, wind power, the more mature systems (with the exception of hydro power) of the available renewable energy supply, and nuclear power, a technology seen as producing large amounts of electricity with very few associated greenhouse emissions, have been promoted but also pitted against each other by analysts and policy makers. This work aims to provide a balanced analysis of wind power and nuclear power with respect to their effects on the natural environment. As such, modeling has been undertaken of a Generation III+ nuclear reactor, an onshore wind farm located in southern Scotland and an offshore wind farm near the Thames estuary while environmental indicators have been created to permit the comparative assessment of these three electricity generation technologies, in a U.K. context. These indicators thus facilitate an assessment of the energy requirements, the associated greenhouse gas emissions, the natural resource requirements, as well as the displaced carbon dioxide emissions from operation of each power plant. A parametric analysis has also been conducted to show the range of likely variations in each indicator’s values. The results of this research show that all three technologies demonstrate similar performance with respect to their energetic and environmental impacts. More specifically, the wind farms demonstrate better energy gain ratios than the nuclear power plant when they are credited for not depleting non-renewable fuel sources. The wind farms also are shown to pay back their energy investments faster than the nuclear power plant. On the other hand, the nuclear power plant is found to produce slightly lower greenhouse gas emissions than either onshore or offshore wind farms. With respect to the assessment of natural resource depletion, it is estimated that both wind farms need more land per unit of electricity produced than the nuclear power plant, but all three power plants permanently sequester similar amounts of water. The wind farms and the nuclear power plant are found to have similar performance with respect to their material requirements, while the calculation of the avoided emissions factors for all technologies are of similar orders of magnitude. All results are shown to be highly sensitive to the assumptions made about the prospective lifecycles, and as such caution should be exercised when drawing conclusions about any comparative advantages. Nethertheless both technologies are clearly shown to have lower environmental impacts than traditional electricity generation technologies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

"Table 21" of "Photoproduction of ω\omega mesons off protons and neutrons"

Inclusive differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.250-1.300 GeV

"Table 21" of "Photoproduction of ω\omega mesons off protons and neutrons"

Inclusive differential cross-sections of $\omega$ mesons produced off the free proton versus $\cos(\theta^\omega_{\mathrm{c.m.}})$ and versus the momentum transfer to the nucleon, $t$, for incident photon energy $E_\gamma$ = 1.250-1.300 GeV