Newswise — Discoveries leading to the suppression of edge localized modes (ELMs) — sudden bursts of heat that can damage the inner walls of doughnut-shaped fusion facilities called tokamaks — have earned physicists Raffi Nazikian, Qiming Hu, and Jong-Kyu Park the 2021 awards for their research achievements at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics  Laboratory (PPPL). The trio won the Kaul Foundation Prize for Excellence in Plasma Physics Research and Technology Development that comes this year with cash awards of $7,500 for each winner. Former PPPL director Ronald Davidson endowed the awards by donating to Princeton University a portion of the gift he received as the 1993 recipient of the Award for Excellence in Science, Education and Physics from the Kaul Foundation in Tampa, Florida.

Steve Cowley, PPPL director, announced the honors during his Dec. 17 State of the Laboratory address that reviewed major developments over the past year. Also honored was Tim Stevenson, leader of the National Spherical Torus Experiment-Upgrade (NSTX-U) Operations & Heating Systems Group, who won the 2021 Distinguished Engineering Fellowship. For that story click here.

Vast energy
Fusion reactions combine light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei, or ions, that makes up 99 percent of the visible universe — to generate vast energy. Scientists around the world are seeking to reproduce and control fusion on Earth for a virtually inexhaustible supply of safe and clean power to generate electricity. At PPPL, the flagship NSTX-U tokamak uses powerful magnetic fields to control the plasma and keep it from dispersing. 

The recent Kaul winner discoveries could speed on Earth the development of fusion energy. “Jong-Kyu, Qiming, and Raffi have made groundbreaking progress on understanding how 3D magnetic fields can improve and control plasma stability and confinement,” said Jon Menard, deputy director for research at PPPL. “This work is vital to ITER burning plasmas and future fusion pilot plants. They are highly deserving of this award.”

Producing the 3D magnetic fields the physicists addressed are special coils that perturb the symmetrical flow of plasma that leads to ELMs. These external coils are separate from the major ones that produce the magnetic fields that confine and control the plasma. Following are profiles of the three award-winning researchers, whose honors include plaques that cite their “seminal contributions leading to the quantitative understanding and optimization of 3D magnetic fields for the suppression of edge-localized-modes in tokamaks.”

Raffi Nazikian
This year’s Kaul award is the second that Raffi Nazikian, who grew up in Australia, has won since he joined PPPL in 1990 and has been stationed at the DIII-D National Fusion Facility that General Atomics operates for the DOE in San Diego. “Receiving a second Kaul award is a great honor,” said Nazikian, who shared the first award with former PPPL researcher Guoyong Fu in 1998. “A lot has changed since then,” Nazikian said. “However, the things that do not change at PPPL are outstanding colleagues and great science."

While heading the ITER and Tokamak Department at PPPL Nazikian worked closely with fellow Kaul winners Qiming Hu and Jong-Kyu Park to develop a model to predict the explosive ELM hazard that ITER, the huge international fusion experiment under construction in France, and other tokamaks must contend with. In working on the problem Nazikian intuited that by combining the separate simulation codes that Hu stationed at DIII-D and Park at PPPL were using, a quantitatively reasonable understanding of the process of ELM suppression by 3D fields could be obtained. 

“Jong-Kyu was working on how a toroidal [or ring-shaped] plasma responds to 3D fields in a global sense and how you can shape the 3D fields to get the response that you wanted,” Nazikian said. “What Jong-Kyu could not do was say how much of that 3D field you needed to suppress ELMs. Qiming came along with a code that he used to understand how magnetic islands formed in a straight-sided cylinder. By plugging the toroidal solution from Park’s code into the cylindrical calulation from Hu, we found that we could reproduce the complex behavior of the plasma observed during ELM suppression.”

Moreover, he said, “we combined the two codes in a rather ad hoc way that turned out to work, much to everyone’s surprise. We got really lucky. The work has opened up all sorts of interesting new questions that are being explored using more sophisticated physics understanding.”

Nazikian has helped to solve fusion and plasma physics problems since receiving his doctorate from the Australian National University in Canberra in 1990 and joining PPPL that year. He has since been elected a fellow of the American Physical Society (APS) and named a distinguished APS lecturer, and has held management positions ranging from leader of the DIII-D Collaborations division at PPPL to head of the ITER and Tokamak Department. In the latter role he focused on developing initiatives and partnerships to resolve physics issues on ITER and helping to prepare the technical basis for creating U.S. fusion energy. 

Nazikian lives in the San Diego area with his family. He grew up with microscopes and telescopes. “I was three years old when I fell in love with the wonder of science. I remember running breahtlessly to my dad, who was in the shower, to tell him that there were living things that you could not be seen by eye. He told me that everyone knows. I was very upset with him that he did not think to tell me about something so important. Since then, it was microscopes and telescopes.  I just recently bought a pretty nice scope that I recently took to Joshua Tree National Park for deep sky viewing.”

Qiming Hu
Qiming Hu has delved into the physics of ELM suppression and controlling ELMs in ITER since he joined the PPPL team at DIII-D in 2017. He started under Raffi Nazikian and now reports to Jong-Kyu Park and has authored or co-authored many refereed papers with both of them. His paper on the analysis of the successful suppression of ELMs on DIII-D became the cover and featured article in the journal Physics of Plasmas in 2019. 

That paper coupled the TM1 code that Hu was using with Park’s GPEC code to address the mechanics behind ELM suppression. Validating the break-through findings were experiments on DIII-D and other tokamaks that demonstrated the success of the theoretical predictions. “Jong-Kyu told me about the GPEC code,” Hu said, “and the code I am using, the TM1, addressed another issue. We combined the two codes and that was the background of our work.” 

Receipt of the Kaul award surprised and gratified Hu. “It is my great honor to be selected for the Kaul Prize, and especially thankful to share it with Raffi and Jong-Kyu, as we have closely worked together for the past years.” he said. “I am also very fortunate to have worked with a group of talented researchers to identify the key physical mechanisms behind ELM suppression with 3D magnetic fields.”

Hu earned his doctorate in plasma physics in 2014 from Huazhong University of Science and Technology in Wuhan, China, and worked for three years as a lecturer and researcher there before joining PPPL, where he is a member of the research staff. While at the university he conducted research on the Joint Texas Experimental Tokamak (J-TEXT), a medium-sized fusion device that the University of Texas at Austin designed and built and shipped to the science and technology school in 2003. “That’s where I first worked on a tokamak,” Hu said.

He now is building on his findings to produce more predictions for suppressing ELMs on ITER plasma to the extent that such plasma can be calculated on the far larger and more powerful international machine. ITER must control the sudden bursts of ELM heat to prevent them from melting the tungsten tiles that will line the tokamak’s inner walls.

Hu lives with his wife, Huan Li, and sons Qingyun Hu, 7, and Qingyu Hu, 5. The family arrived in 2018 a year after Hu joined PPPL. When Hu is not working and battling ELMs he enjoys playing tennis and badminton and hiking with his sons in the San Diego countryside. “The trails here are beautiful,” he said, “and we love the outdoors.”

Jong-Kyu Park
Principal research physicist Jong-Kyu Park was surprised to learn that he was among the 2021 Kaul Award winners. He immediately credited the award to his close collaboration with the other two awardees. “I have to thank Raffi’s great leadership and Qiming’s dedication,” he said. “I am grateful to be a part of this group.” Park also acknowledged that winning a Kaul award at PPPL was amazing. “I’m so honored to win this incredible award, especially since there are so many great plasma physicists at the Lab who deserve the award,” he said. 

Park received his bachelor’s and master’s degrees in nuclear engineering from Seoul National University in 2000 and 2002, respectively. He received a doctorate from the Princeton University Program in Plasma Physics in 2009, with PPPL’s Jonathan Menard and Columbia University’s Allen Boozer as his advisors, and joined the Laboratory that year.  

The American Physical Society (APS) honored Park with the Marshall N. Rosenbluth Outstanding Doctoral Dissertation Award in 2010 and he also received a U.S. Department of Energy’s (DOE) Early Career Award in Fusion Energy that year.

“I have always been interested in studying innovative ways to create electricity,” Park said. “In South Korea, I was fascinated by the challenges and benefits of nuclear fusion, but soon realized that to pursue that field I had to understand plasma physics.”

Park currently conducts research for both the ITER and Tokamaks and the NSTX-U departments at PPPL and teaches in the plasma physics graduate program. His research has focused on understanding plasma dynamics and transport in tokamaks along with 3D magnetic perturbations that can alter various plasma instabilities.

“It is a critical part of our work to make tokamaks more reliable and effective,” Park said. “I enjoy my research since it can also leverage physics understanding across twisty magnetic confinement concepts known as stellarators.” 

Park lives in Princeton with his wife, Kailey, and five-year-old son, Theo, and plays tennis and golf in his spare time. “Of course I love Princeton,” he said. “It’s peaceful and full of good people. After Seoul, I consider it my hometown.” 

As for his future research plans, Park says they’re simple: “Just like many of us in this field, I am just going to keep doing magnetic fusion research and collaborating around the world to see our mission realized in our lifetime.”

PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit