Intense Beam Dynamics with a the IBEX linear Paul trap

The next generation of intense hadron beam accelerators will be used to generate proton, neutron and muon beams for scientific and societal applications. The dynamics of particle beams in this regime is inherently non-linear, even in a linear focusing system, due to the presence of imperfections. These systems usually have no analytical solutions and can be extremely challenging to model accurately in computer simulations. Yet, future machines and novel accelerator concepts will require a detailed understanding of the interplay between space charge effects, resonances and non-linear interactions. The primary aim of this project is to establish a greater understanding of fundamental beam dynamics of intense hadron accelerators using a new experimental apparatus. The project will focus on the physics of beams in accelerators, however the impact of this project may be wide-ranging from potential new developments of diagnostics for linear Paul traps which may be applied in other fields to insights which could impact on major future accelerator projects in the UK and internationally. The student will investigate intense beam dynamics effects using a new experimental apparatus, the 'Intense Beam Experiment' (IBEX) located at the STFC Rutherford Appleton Laboratory in Oxfordshire. This experiment is not an accelerator, but a physically equivalent system called a linear Paul trap, where Argon ions are confined in the lab frame using rf quadrupole electrodes. This system can approximate the transverse dynamics of intense particle beams and rf perturbations can be applied to study imperfections. The project will be carried out in close collaboration with the Intense Beams Group at RAL and in wider collaboration with Prof. Hiromi Okamoto's beam physics group at University of Hiroshima. Initial investigations with the linear (quadrupole) trap will be benchmarked against results from a similar setup at Univ. Hiroshima and will include studies of integer resonance crossing initially in the low intensity regime and later in a space charge dominated regime. This initial research pertains to fundamental beam dynamics topics particularly relevant to non-scaling fixed field alternating gradient accelerators, where little work has been done to establish how the phenomenon of resonance crossing changes with intense beams. The student will then be expected to contribute to developing their own research questions on other topics using the IBEX apparatus. One such direction may be the stability of novel lattice configurations for future accelerators, using IBEX to map out stability diagrams in the first and higher stability regions and investigating sensitivity to space charge effects. Another possible direction is to establish a test case for half integer resonance crossing and benchmark against experiments on the ISIS synchrotron. Once investigations with the quadrupole trap are underway, the student may contribute to the development of novel diagnostics for the system in order to observe effects of the ion plasma in-situ, or to measure quadrupole or other modes.This project is well aligned with STFCs strategy for future facilities, including the investigation of a new neutron spallation source on a 15-20 year timescale.