11.07.2024

30th PHD Interview

“An energy source that is emission free, renewable and uses almost no fuel sounded too good to be true… Being a gear in the machine that tries to make it happen gives a sense of application that I enjoy.” - Dipl.-Ing. Johannes Brötzner (University of Technology of Vienna)

PhD student Johannes Brötzner
Johannes Brötzner

What is the topic of your Ph.D. thesis?

My thesis falls within the broader topic of plasma-wall interaction. I try to understand what happens when ions from the fusion plasma collide with the walls of a reactor.

What is the focus of research?

I study the erosion of the plasma facing components (PFC) that is caused by a process called sputtering. The energetic plasma ions can eject material from the walls, like a microscopic sandblaster. In our lab we investigate different materials to see how fast they are sputtered, how this changes their surface (both in composition and structure) and in turn how surface morphology can influence the sputtering properties of a material.

What is the benefit for fusion research?

Knowledge and understanding of these effects of course helps to better estimate the lifetime of a fusion reactor. Minimising the sputtering of the PFCs additionally prolongs this lifetime and reduces cooling of the plasma by sputtered impurities.

What are the biggest challenges?

In the recent past we have dealt with (nano-)structured materials a lot. These are not always easy to work with, so we had to come up with clever ways to augment our experiments to be able to handle also these types of samples. Moreover, we accompany our experiments with numerical simulations. The more complex the samples get, the more time consuming these calculations become.

What plans do you have for your future? What will you be doing in five years? Would you like to continue research or are you going to work in the industry?

This I cannot tell for sure at the moment. There is at least one more year to my PhD studies, and after that I would like to work in a sector that serves the public. Whether this will be in the energy industry, in academia or even in fusion (or maybe something completely different), I do not know just now.

What was your motivation to write a fusion relevant Ph.D. thesis? What fascinates you about nuclear fusion?

During the bachelor’s programme of my physics studies I first came across fusion. An energy source that is emission free, renewable and uses almost no fuel sounded too good to be true. (And in a way, it kind of still is too good to be true as we do not have commercial fusion power plants yet.) But being a gear in the machine that tries to make it happen gives a sense of application that I enjoy.