Simulation of a gas-filled solenoid : optimizing functionality and expanding applicability

Abstract

The potential of gas-filled solenoids for separating fusion reaction products produced using particle accelerators has recently been realized at the ANU. Their capability of high efficiency transportation of fusion products and beam particle suppression means that they can be used to measure fusion cross-sections with better precision than practically achievable with other separating mechanisms. In order to effectively configure and use these solenoidal separators, simulation of the ions paths is required to determine and optimize the transmission of the fusion products. This thesis discusses the physical processes that need to be taken into account when doing this simulation, and describes the code Solirte developed to perform the simulations. Since the simulation requires following the trajectories of a large number of ions, the implementation of the simulator on commodity graphics cards (in order to substantially increase the performance) is described. The interactions between the high-speed heavy ion and the gas filling the solenoid depends on the mean charge state, which is typically taken from empirical models. Increased accuracy in these values will give an increased accuracy in the final results. A self-consistent approach is therefore developed in this thesis to derive the mean charge state and initial angular distribution of the ERs. The simulator support and experimental analysis methods required to perform these techniques are described and applied to the 58Ni + 64Ni fusion reaction. The final chapter deals with expanding the range of reactions that can effectively be studied by introduction of a gas mixture in the solenoid bore. The simulator implementation and the experimental considerations required when using a gas mixture are discussed, and several systems are identified where gas mixtures could allow improved or easier measurements.