KIT Summer School 2022

In September, the grads visited Germany to attend the 14th International School on Fusion Technologies at KIT in the beautiful Karlsruhe. This was the first time the school had run since before the pandemic, so grad scheme alumni from the 2019 cohort joined the 2020 and 2021 cohorts as we journeyed together for the long-anticipated summer school.

In total there were 31 of us, making up about half of the conference attendees! Our grads represented a variety of departments: CED (Central Engineering), RACE (our Robotics facility), H3AT (our Tritium lab), H&CD (Heating & Current Drive), OCE (Office of the Chief Engineer), Technology, and myself in Advanced Computing.

We met attendees from all over the world, representing both academic and industrial backgrounds, all congregated together to learn more about the technology and engineering that is making fusion energy a reality. After two years largely working in our bedrooms during lockdown, or otherwise focussed on our own projects, it was a refreshing reminder of the context which each of our own day-to-day work fits into, and the global nature of our quest.

KIT Summer School Group Photo 2022 ~ Credit: Mihaela Ionescu-Bujor

The school covered twelve key fusion technology topics over five days:

• Monday opened with an introduction to fusion and plasma physics, by guest lecturers from EUROfusion, the CEA, and our own UKAEA, followed by a lecture on neutronics. 
  
  These topics comprise the core physics of fusion energy: the coupling of magnetohydrodynamic and nuclear considerations that make the magnetically confined deuterium-tritium reaction a viable route to the decarbonised future of energy generation.
  
  
• Tuesday ramped things up by delving into the various plasma heating technologies, plasma diagnostics, and the fusion power plant fuel cycle with guest lectures from UKAEA and the CEA. Tuesday also featured a tour of the gyrotron test stand and was rounded off by tours of KIT’s fusion materials and tritium laboratories.
  
  Developing technologies to efficiently heat and fuel a fusion power plant are very much the sort of practical engineering challenges that define the modern stage of fusion R&D, as distinct from the theoretical physics groundwork solved in the preceding decades.
  
  
• Wednesday covered two major fusion technologies: breeder blankets (required for providing tritium to the fuel cycle), and superconductive magnets (required for plasma confinement).
  
  Breeder blankets are a technology unique to fusion, and a personal favourite of mine, so it was very interesting to learn about the designs being tested in ITER with a guest lecture from F4E (the ITER organisation's European contribution). Tritium is the rarest and most expensive fusion fuel, so a commercial fusion power plant will need to breed tritium in-situ to sustain its fuel cycle and provide a tritium inventory. An elegant solution to this challenge lies in lithium, which emits tritium upon capture of a high energy neutron: exactly the kind of neutron emitted by the main fusion reaction. Thus, a breeder blanket sits snuggly around the vacuum vessel performing two functions: absorbing high energy neutrons and turning their energy into electricity while returning the produced tritium to the power plant fuel cycle.
  
  Superconductive magnets are another fascinating technology used in only a handful of modern applications (including MRI scanners and maglev trains). They are crucial to the design of most fusion power plants, because confining a fusion plasma in a tokamak requires a strong magnetic field. The field strength of an electromagnet grows in line with the current applied, which in a conductor leads to resistive heating as electrons collide with atomic nuclei in the material. Superconductors, however, quite literally have zero resistance, allowing for strong magnetic fields to be produced without melting the magnet in the process.
  
  
• Thursday discussed the materials for fusion devices, including the tungsten divertors. Fusion materials require special properties, capable of withstanding exposure to high heat flux and neutron irradiation for extended periods of time. Neutrons become embedded in these materials, causing microscopic impurities in the lattice which act to embrittle them. At the same time, the high temperatures involved act to soften the materials. Understanding the complex interplay between these phenomena is crucial to engineering a fusion power plant from materials capable of operation throughout its lifetime.
  
  We also discussed the safety, socioeconomics, and waste considerations of fusion with guest lectures from F4E and ENEA. I was glad to see the inclusion of this topic, as the positive socioeconomic impact of fusion is what drew so many of us into the field. The potential to decarbonise the energy supply, while avoiding the waste and safety issues of fossil fuels and nuclear fission is attractive, but it doesn’t come for free; the only way to realise that goal is to integrate safety and waste considerations directly into the design processes in a transparent way, and I’m proud to see that that is exactly how it’s being done.
  
  
• Friday closed with remote handling and maintenance, something my robotics colleagues in RACE are very experienced with, all topped off with guest lectures from the Max Planck Institute on the ASDEX Upgrade and Wendelstein 7-X stellerator facilities. It was great to hear how much progress had been achieved in stellarator technology, especially since it's not something that gets researched much at UKAEA. It was another reminder of how fusion is a collaborative worldwide effort with many organisations and countries involved in bringing the future closer, and a great topic for the final day of KIT.

Of course, we couldn’t visit Karlsruhe without sampling some of their world-famous beer. Luckily, we were honoured to be provided an excellent evening meal at the Badisch Brauhaus (“Badisch Brewery”) which was enjoyed by all.

Evening Meal at the Badisch Brauhaus ~ Credit: Luke Humphrey

On behalf of the graduate scheme, I’d like to thank the organisers for getting this event running again after the pandemic. It was a fantastic opportunity to learn from experts, communicate with others working in fusion, and to enjoy a week in Germany.

The famous Schlossgarten of Karlsruhe ~ Credit: James Hodson

Finally, if anybody reading this would like the attend, the next Summer School will take place at KIT in Karlsruhe, Germany from September 11 to 15, 2023. I invite you to keep an eye on this page for details: https://summerschool.fusion.kit.edu/index.php.

You can also check out our own Plasma Physics Summer School here at UKAEA in Oxfordshire, UK at: https://culhamsummerschool.org.uk/.

Article by: Luke Humphrey