PhD Success!

David Posthuma De Boer with examiners Philip Burrows (JAI) and Elias Metral (CERN)

Congratulations to David Posthuma De Boer on completing his PhD Viva! He submitted his PhD thesis on "Studies of Beam Impedance with Related Beam Stability and Loss Effects on a High Intensity Proton Synchrotron".

Coherent beam instabilities are a key constraint on the performance of high-intensity hadron accelerators. At the ISIS Neutron and Muon Source, one such instability drives beam-loss, limiting beam power on target and ultimately science output. This thesis addresses the broader challenge of beam instabilities with a detailed case study at ISIS. It presents a new and comprehensive characterisation of key vertical impedance sources on ISIS, using a combination of experimental methods and new numerical tools and techniques, such as RWAL[1]. When this impedance model is fed into the new linearised Vlasov solver, PyTMCI[2], it successfully predicts key instability features in two different operating modes of ISIS. The thesis concludes that the instability is driven by capacitively coupled RF screens, which are common components at rapid cycling synchrotrons around the world. It further presents a validated mitigation approach which is undergoing initial trials at ISIS.

[1] - https://github.com/stfc/RWAL

[2] - https://github.com/stfc/PyTMCI