A geometric optics method for high-frequency electromagnetic fields computations near fold caustics—Part II. The energy

AbstractWe present the computation of the amplitudes needed to evaluate the energy deposited by the laser wave in a plasma when a fold caustic forms. We first recall the Eulerian method designed in Benamou et al. (J. Comput. Appl. Math. 156 (2003) 93) to compute the caustic location and the phases associated to the two ray branches on its illuminated side. We then turn to the computation of the amplitudes needed to evaluate the energy. We use the classical geometrical form of the amplitudes to avoid the blow up problem at the caustic. As our proposed method is Eulerian we have to consider transport equations for these geometrical quantities where the advection field depends on the ray flow. The associated vector field structurally vanishes like the square root of the distance to the caustic when approaching the caustic. This introduces an additional difficulty as traditional finite difference scheme do not retain their accuracy for such advection fields. We propose a new scheme which remains of order 1 at the caustic and present a partial theoretical analysis as well as a numerical validation. We also test the capability of our Eulerian geometrical algorithm to produce numerical solution of the Helmholtz equation and attempt to check their frequency asymptotic accuracy

The effect of fission-energy Xe ion irradiation on the structural integrity and dissolution of the CeO2_2 matrix

© 2016 The Authors.This work considers the effect of fission fragment damage on the structural integrity and dissolution of the CeO₂ matrix in water, as a simulant for the UO₂ matrix of spent nuclear fuel. For this purpose, thin films of CeO₂ on Si substrates were produced and irradiated by 92 MeV 129Xe23+ ions to a fluence of 4.8 × 1015 ions/cm2 to simulate fission damage that occurs within nuclear fuels along with bulk CeO₂ samples. The irradiated and unirradiated samples were characterised and a static batch dissolution experiment was conducted to study the effect of the induced irradiation damage on dissolution of the CeO₂ matrix. Complex restructuring took place in the irradiated films and the irradiated samples showed an increase in the amount of dissolved cerium, as compared to the corresponding unirradiated samples. Secondary phases were also observed on the surface of the irradiated CeO₂ films after the dissolution experiment.The irradiation experiment was performed at the Grand Accélérateur National d’Ions Lourds (GANIL) Caen, France, and supported by the French Network EMIR. The support in planning and execution of the experiment by the CIMAP-CIRIL and the GANIL staff, especially, I. Monnet, C. Grygiel, T. Madi and F. Durantel is much appreciated. Thanks are given to I. Buisman and M. Walker from the Department of Earth Sciences, University of Cambridge for help in conducting electron probe microanalysis and polishing the samples, respectively. A.J. Popel acknowledges funding from the UK EPSRC (grant EP/I036400/1 and EP/L018616/1) and Radioactive Waste Management Ltd (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority, contract NPO004411A-EPS02)

Research data supporting the publication: 'The effect of fission-energy Xe ion irradiation on the structural integrity and dissolution of the CeO2_2 matrix'

Project: PhD work by A.J. Popel: ‘The effect of radiation damage by fission fragments on the structural stability and dissolution of the UO2 fuel matrix’. The Excel file ‘XRD_CeO2’ with raw XRD data supporting the CeO2 powder XRD results The Text files ‘sample1_wt’ and ‘sample2_wt’ with raw EPMA data supporting the EPMA analysis of the two bulk CeO2 samples The Excel file ‘ICP-MS data’ with output ICP-MS data and calculations for water and acid dilutions supporting Figures 5 and 6 and ICP-MS results in the publication: A.J. Popel, S. Le Solliec, G.I. Lampronti, J. Day, P.K. Petrov, I. Farnan, The effect of fission-energy Xe ion irradiation on the structural integrity and dissolution of the CeO2 matrix, J. Nucl. Mater. 484 (2017) 332-338, https://doi.org/10.1016/j.jnucmat.2016.10.046. The XRD analysis was performed to verify the identity of the as-supplied bulk samples and check for other phases. The data were generated on the 5th of June 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK. A bulk sample of the as-supplied CeO2 was powdered using mortar and pestle and analysed on a D8 Bruker diffractometer equipped with a primary Ge monochromator for Cu Ka1 and a Sol-X solid state detector operating in standard Bragg-Brentano geometry. The sample was spun during signal collection and a zero-background sample holder was used. The EPMA analysis was performed to check the composition of the as-supplied bulk samples. The data were generated on the 3rd of July 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK. Prior to the analysis, the samples were embedded in a resin, polished and carbon coated to ensure conductivity for the analysis using a Cameca SX-100 electron microprobe analyser. Calibration of the equipment was performed using a set of rare earth elements. The ICP-MS analysis was performed to measure 140Ce concentration in the extracted solutions. The data were generated on the 23rd of July 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK, on a Perkin Elmer SCIEX Elan DRC II quadrupole ICP-MS. The data can be accessed through the University of Cambridge Data Repository