The path leading down to Sandfly Bay, Otago Peninsula

Old Members’ Trust Graduate Conference and Academic Travel Fund Report – Will Clarke (2021, DPhil Theoretical Physics)

New Zealand, or Aotearoa (meaning land of the long white cloud) in Māori, is often considered the most beautiful country on Earth. Its rugged mountains, rolling green hills and vast grassy fields enabled Peter Jackson to bring the Lord of the Rings films to life. While I was at home in Sydney, Australia, visiting my family over Christmas, I was given a special opportunity to visit one of my supervisor’s collaborators, Associate Professor Jonathan Squire, at the University of Otago in Dunedin (Ōtepoti in Māori), on the South Island of New Zealand.

The focus of my DPhil so far has been the modelling of turbulent heat transport in nuclear fusion devices. Nuclear fusion is the process that powers the stars, where high pressure (due to high temperature and density) causes lighter atoms in a plasma (gas composed of charged particles) to overcome their mutual electric repulsion and fuse, releasing large amounts of energy. Replicating this process in a laboratory setting (sometimes in machines as small as a classroom, but often much larger) requires confining the hot plasma using strong magnetic fields. Maintaining this confinement in a stable and sustained manner is incredibly challenging, but represents a promising direction for clean, renewable energy generation.

The University of Otago Registry Building, next to the banks of the Water of Leith

My research has focused on a simplified model of a plasma in a nuclear fusion device – in particular, how certain

conditions can stir up turbulence in a plasma, causing massive losses of heat (pressure) hence stopping the fusion process. I wanted to take my experience with the simplified system and apply it in a more realistic setting. Dr Squire is an internationally renowned plasma physicist who has begun modelling the turbulence in levitated dipole devices. This type of device consists of a cylindrical metal vessel, inside which a superconducting ring magnet is levitated using magnets on the exterior. The magnetic field is dipolar (similar to the Earth’s magnetic field) with magnetic field lines going from a north pole to a south pole. However, unlike the Earth’s magnetosphere, where energetic particles either bounce between the two poles or crash into the atmosphere, causing auroras, particles in a levitated dipole machine are free to move through the hollow centre of the ring magnet and back to the main bulk around the ‘equator’. In my opinion, it’s a promising technology and one of the simplest designs for a nuclear fusion device. Luckily for me, there’s a burgeoning interest in New Zealand, with a start-up founded in 2021 beginning to do experiments using their device.

St Paul’s Cathedral in the city centre of Dunedin

I spent about a week at the University of Otago, where I was warmly welcomed by Dr Squire, Dr Romain Meyrand and the plasma physics group. We discussed how to extend my current research to the case of a plasma in a levitated dipole machine, and I took the first steps in developing a model for this purpose. I will continue to work with Dr Squire and my Oxford supervisors on this project for the remainder of my final year as a DPhil student, and I am very grateful for the opportunity to start this collaboration. I am also grateful for the opportunity to present my DPhil research to the group in Otago.

Although most of my time was spent working, I was very happy to be able to explore the city of Dunedin in the afternoons and evenings. Taking its name from the Scottish Gaelic for Edinburgh ‘Dùn Èideann’, Dunedin is the oldest city in New Zealand, with a rich cultural heritage due to both the Māori, who arrived in around 1100 CE, and Scottish immigrants who came much later in the 19^th century. In the city centre, there is a large statue of the famous poet Robert Burns, whose nephew, the Reverend Thomas Burns, was a prominent religious leader in Dunedin. The University of Otago was founded in 1869 during a gold rush period, which saw the construction of a number of buildings in the Victorian and Edwardian styles. At the same time, Dunedin is a vibrant university town; there is a mix of history, urban charm, cutting edge street art, crafts, and natural beauty. It has spectacular beaches, landscapes, a castle, museums, churches, and delicious locally produced food and wine

Sea lion after a long day at work

On the doorstep of Dunedin sits the Otago peninsula, home to an extraordinary range of native and endangered wildlife including the northern royal albatross (the only mainland nesting colony in the world is at Taiaroa Head on the peninsula), little blue penguins, yellow-eyed penguins, fur seals, sea lions, and a vast array of birds and plants. Dr Squire very kindly took me to visit Sandfly Bay one evening to watch the sea lions on the beach – a truly amazing experience given that we walked within about five metres of one sleeping in the middle of the path to the beach! For those interested in the wildlife, you can view the latest royal albatross chick on a livestream, as part of a collaboration with Cornell University.

My trip to New Zealand would not have been possible without the financial support of the Old Members’ Trust, and I’d also like to thank the senior tutor, Dr Bell, and the graduate studies officer, Ms Franklin, for approving my application. I am truly thankful to Dr Squire and the Otago group, and I hope to return to New Zealand in the future (although hopefully with more time to be a tourist).

Published: 14 March 2025

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