P.H.D. Student Interviews - Part 9

"I like the challenge to put modern knowledge into practice"

Philipp Lorenz Ballauf, Ph.D. student at the University of Innsbruck

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

Reactive ion surface collisions, which are carried out and analyzed on a particle level.

What is the focus of your research?

In the newly build experiment mass selected ions collide with surfaces made of the same materials, which are used inside of a fusion reactor. A time-of-flight mass spectrometer detects the created product ions. Hence, there is perfect control over the projectile ions, for example, I switch between deuterium ions, D2 + and D3 + at the moment to understand the mechanism of the synthesis of beryllium-deuterium compounds. Other features of the apparatus that help are: Positive and negative ions possible on either side of the surface, the surface is heatable and particularly the kinetic energy, with which the projectiles meet the surface, is accurately adjustable. 

What is the benefit for fusion research?

Since the magnetic confinement of fusion plasma is not perfect, ions collide regularly with the inner surfaces of the reactor (blanket, divertor). These impacts are performed under simple and controllable conditions in the experiment. The advantage of our apparatus is to understand and characterize particular reactions on a particle level, in contrast to the approach to measure macroscopic parameters in the plasma, which is a highly complex environment.

Currently I am investigating impacts of deuterium on a beryllium surface in order to investigate how bounds are formed between those in a plasma wall interaction. This is feasible for the not yet solved problem of "tritium retention". This is the implantation of radioactive tritium in the walls of a fusion reactor. In future, when reactors become even bigger than ITER and shall have long operation cycles, this is a key challenge.

What are the biggest challenges?

The biggest challenge so far was to build an experiment, which is unique in its form. The reason for this is the low signal intensity -after the collision indeed single ions are detected. Some 10 product ions per second are already 100 times more than at the beginning of our experiments. Now the next challenge starts with the interpretation of the first data.

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?

Concerning my research activities the planning period is short. If you do something for the first time, no one knows how it works or how long it will take. I think I am able to cope with this task in future as well. But I also like the challenge to put modern knowledge into practice. Whatever it will be in the long run, one thing is clear to me: I don't want to work on improvements in the per thousand range. I like to put my effort into something new and unconventional. If I get the possibility to work on the bridge between science and technology, I will be happy to take this opportunity - no matter from which side.

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

Well, it is simple and discussed often: man-made global warming is a fact. You can discuss how severe it will be, but I am convinced that we are better off, if our climate changes as little as possible. I don't want to present nuclear fusion as the solution for all our problems, but it is a necessary supplement to all renewable energy sources. So besides the exciting scientific aspects, societal concerns motivate me as well.