Monte Carlo Particle Lists: MCPL

A binary format with lists of particle state information, for interchanging particles between various Monte Carlo simulation applications, is presented. Portable C code for file manipulation is made available to the scientific community, along with converters and plugins for several popular simulation packages

Simulation Tools for Detector and Instrument Design

The high performance requirements at the European Spallation Source have been driving the technological advances on the neutron detector front. Now more than ever is it important to optimize the design of detectors and instruments, to fully exploit the ESS source brilliance. Most of the simulation tools the neutron scattering community has at their disposal target the instrument optimization until the sample position, with little focus on detectors. The ESS Detector Group has extended the capabilities of existing detector simulation tools to bridge this gap. An extensive software framework has been developed, enabling efficient and collaborative developments of required simulations and analyses -- based on the use of the Geant4 Monte Carlo toolkit, but with extended physics capabilities where relevant (like for Bragg diffraction of thermal neutrons in crystals). Furthermore, the MCPL (Monte Carlo Particle Lists) particle data exchange file format, currently supported for the primary Monte Carlo tools of the community (McStas, Geant4 and MCNP), facilitates the integration of detector simulations with existing simulations of instruments using these software packages. These means offer a powerful set of tools to tailor the detector and instrument design to the instrument application

Inference of α\alpha-particle density profiles from ITER collective Thomson scattering

The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born $\alpha$-particles. Based on the present design of the diagnostic, we compute and fit synthetic CTS spectra for the ITER baseline plasma scenario, including the effects of noise, refraction, multiple fast-ion populations, and uncertainties on nuisance parameters. As part of this, we developed a model for CTS that incorporates spatial effects of frequency-dependent refraction. While such effects will distort the measured ITER CTS spectra, we demonstrate that the true $\alpha$-particle densities can nevertheless be recovered to within ~10% from noisy synthetic spectra, using existing fitting methods that do not take these spatial effects into account. Under realistic operating conditions, we thus find the predicted performance of the ITER CTS system to be consistent with the ITER measurement requirements of a 20% accuracy on inferred $\alpha$-particle density profiles at 100 ms time resolution.Comment: 17 pages, 11 figures. Accepted for publication in Nucl. Fusio

High power microwave diagnostic for the fusion energy experiment ITER

Microwave diagnostics will play an increasingly important role in burning plasma fusion energy experiments like ITER and beyond. The Collective Thomson Scattering (CTS) diagnostic to be installed at ITER is an example of such a diagnostic with great potential in present and future experiments. The ITER CTS diagnostic will inject a 1 MW 60 GHz gyrotron beam into the ITER plasma and observe the scattering off fluctuations in the plasma - to monitor the dynamics of the fast ions generated in the fusion reactions

Modelling and CFD analysis of the DYNASTY loop facility

In this paper, CFD assessment of the DYNASTY natural circulation loop, adopting a RANS turbulence modeling approach, is performed using the OpenFOAM open source toolbox. The DYNASTY facility is designed to investigate the stability and dynamics of heat-generating fluids, in particular molten salts, in a natural or forced circulation regime and as such, it is one-of-a-kind, large scale facility for studying the natural circulation in presence of distributed heating. In this work, a CFD model of the facility is set up and validated by comparing the model results to experimental data obtained during the initial testing campaign of the facility, with water as working fluid. In particular, the equilibrium state of the system is investigated in terms of the mass flow dynamic behaviour and the temperature difference across the cooler section of the loop. It is shown that the CFD simulations adopting the k − ω SST turbulence model best reflect the experimental results. The CFD results are also in agreement with a simplified 1D modeling as well as an analytical solution