18. PHD Interview

"In 5 years we will be very close to the first plasma in ITER. Being a part of that sounds really intriguing to me."

Georg Harrer, doctoral candidate at the Institute of Applied Physics (TU Wien)

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

My topic is called “Origin and transport of small ELMs”.

What is the focus of research?

As the title suggests my research focuses on exploring the so-called small Edge Localized Mode regime of Tokamak fusion devices. ELMs are “the solar eruptions of Tokamaks”. They cause large bursts of particles and energy out from the 100 Mio °C hot centre of the plasma to the wall of the device that should be kept far below 1000 °C. When we scale up to larger machines like ITER and DEMO the high strains caused by large regular ELMs cannot be endured by materials. One way to deal with this challenge is to operate the machine in such a way, that the large ELMs are replaced by more tolerable small ELMs.

What is the benefit for fusion research?

During the course of my thesis the small ELM regime that we found on ASDEX Upgrade turned out to be a promising operational scenario for future fusion devices. It shows high performance, whilst causing far less heat load on the plasma facing components.

What are the biggest challenges?

A big challenge was to show, that this small ELM regime was not just exclusive in ASDEX Upgrade. I was therefore super happy when we could reproduce our results in the Swiss Tokamak TCV. Recently our Chinese colleagues at the EAST tokamak were also able to find a comparable operational regime which increases my confidence that we are on to something here.

Which plans do you have for your future? What will you do in 5 years? Would you like to continue research or are you going to work in industry?

In 5 years we will be very close to the first plasma in ITER. Being a part of that sounds really intriguing to me. On the one hand I enjoy the collaborative aspect of the work in research and all the traveling. On the other hand, family is very important for me and I really like being at home “im Waldviertel”. Only time will tell…

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

I came in contact with fusion research early in my studies during a project thesis. What I liked the most was the closeness of experiment and modelling. In the control room of a tokamak there is always active exchange between experimentalists running the machine and theoreticians comparing the results to the predictions of their codes.