Former Merton DPhil student Dr David Hosking (2014) has been awarded the European Physical Society Plasma Physics Division PhD Research Award 2023. David receives the award for his thesis, ‘The decay of MHD turbulence and the primordial origin of magnetic fields in cosmic voids’.
Dr Hosking's thesis proposes a theory of how chaotic magnetic fields in astrophysical environments decay when their source of energy is removed. The thesis introduces a new integral invariant, the 'Saffman helicity invariant', to express the conservation of the random magnetic helicity—a topological quantity related to linkages and twists of magnetic field lines—contained in large volumes of turbulence. The theory implies a slower decay of primordial magnetic fields in the early Universe than did previous models, suggesting consistency between the deduced strength of the modern-day relics of those fields with observational constraints on the magnetic fields in cosmic voids. The thesis also explores the role of so-called Saffman-like invariants in forced turbulence and considers the effect that tangled magnetic fields might have on the propagation of energy through their host media.
Dr Hosking was a Prize Scholar in 2021/22 and studied for his DPhil in Astrophysics at Oxford under the supervision of Professors Alex Schekochihin and Steven Balbus. He now holds a postdoctoral fellowship at Princeton Center for Theoretical Science and a research fellowship at Gonville & Caius College, Cambridge.
“I am delighted to have received the EPS Plasma Physics Division PhD award. I owe thanks to Alex Schekochihin and Steve Balbus for their supervision and for introducing me to some fascinating physics problems. I am grateful also to Merton College for their support both during my time as an undergraduate and as a graduate student.”
Dr Hosking is one of four winners of the 2023 PhD Research Awards. He is the third Mertonian to receive the award, after Archie Bott (2015) was selected in 2020 and Edmund Highcock (2009) in 2014.