Kaden Loring: Optimization of Atomic Density Measurements in Heating Systems for Fusion Reactors (Max Planck Institute for Plasma Physics-Garching)
Kaden Loring: Optimization of Atomic Density Measurements in Heating Systems for Fusion Reactors (Max Planck Institute for Plasma Physics-Garching)
Thanks to the Graduate Research & Internship Program in Germany, I spent three exciting months living and working in the Munich-area while a visiting researcher at Max Planck Institute for Plasma Physics (IPP) in Garching. During this time, I worked with the ITER Technology and Diagnostics group who is responsible for developing a negative hydrogen ion source, a small particle accelerator where hot hydrogen atoms are primed to gain an extra electron, which can be used to help sustain the reactions at the heart of a future fusion energy reactor. My task was to improve their measurements of atomic hydrogen density within the extreme environment of a high-energy ion source.
At Stanford, I am third-year Applied Physics PhD concentrating in the field of fusion energy technology. This field is extremely collaborative due to the nature of large experiments and the positive global impact commercial fusion energy might one day bring to us all. As such, I have followed the news closely for many years describing the ground-breaking work done in fusion research at IPP in Germany and hoped that I could eventually also spend some time working with and learning from some of the greatest minds in the field. That opportunity came this fall, when I began as a visiting researcher at IPP thanks to my GRIP award.
In the second-year of my PhD, I helped develop a laser-based diagnostic, TALIF, which could directly measure the density, temperature, and velocity of hydrogen atoms in plasma environments. When I reached out to IPP about my expertise and desire to complete a research visit with them, my eventual hosts, Dr. Ursel Fantz and Dr. Christian Wimmer, were very excited. Their research group had tried to develop a similar diagnostic to make these same measurements on an experimental negative-hydrogen ion source, but had come up short of their goals for signal resolution. They hoped that with my prior experience I might be able to help them optimize their diagnostic.
Having an accurate picture of the atomic hydrogen population within their ion source is important for understanding the efficiency of the source. In many ways, not having a reliable hydrogen population diagnostic for their ion source research is like trying to optimize a race car without first installing a fuel gauge or speedometer.
Over the course of my stay, I identified a possible path towards improvement and an experiment to test how the idea could be implemented in practice. The hydrogen plasma within their ion source is not a stable state of matter here on earth. For instance, hydrogen ions can readily pick-up electrons at material surfaces. This phenomenon means that hydrogen atom production is increased where plasma comes into contact with material. This is particularly relevant to where they wish to measure within the ion source; adjacent to a large molybdenum-metal grid. The experiment I designed at IPP tested passing the TALIF laser at various distances from molybdenum and stainless steel samples in a hydrogen plasma to find the sweet spot for measurements–close enough that you benefit from surface production of H atoms (increased signal-to-noise) but not so close that the field-of-view is obscured or background noise increases more than the signal.
I plan to publish a journal article from this work in collaboration with my hosts at IPP. Furthermore, I expect to stay in close collaboration with them throughout the remainder of my PhD and beyond. GRIP was a very fruitful experience for me as a scientist!
Outside of research, my time in Germany was also very rewarding on a personal level. One of my proudest accomplishments was my progress in learning German. When I applied to GRIP, I had no German language background. By the time I left Germany, I could comfortably order in German and understand much of what was spoken to me. I made these improvements by regularly attending language cafes, listening to the podcast Coffee Break German on my way to and from work every day, and not being afraid to ask coworkers to explain idiomatic expressions.
I also found great joy in the beauty of my surroundings. Whether it was hiking trips to the Bavarian Alps, singing with friends at Oktoberfest, or simply strolls through Englischer Garten, I felt so grateful to have this moment in my life in such a special place. In fact, I enjoyed myself in the Munich-area so much, that I expect to apply to jobs in Munich after I graduate from Stanford. I am very thankful for the opportunity which the Graduate Research & Internship Program and the Stanford Club of Germany afforded me to experience life in Germany!
