Two PPPL physicists named to high-level DOE positions

Written by
Raphael Rosen
Aug. 22, 2022

Two physicists at the Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have been named to high-level positions within DOE programs. Ahmed Diallo has become a program director focusing on fusion at the Advanced Research Projects Agency-Energy (ARPA-E), and Walter Guttenfelder is the new deputy director of the Innovation Network for Fusion Energy (INFUSE). The physicists began their positions earlier this summer and will remain in them for approximately two years while continuing their duties at PPPL on a reduced schedule.

Fusion, the power that drives the sun and stars, combines light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei — that generates massive amounts of energy. Scientists are seeking to replicate fusion on Earth for a virtually inexhaustible supply of power to generate electricity.

Helping shepherd efforts to innovate energy

Diallo moves into his ARPA-E role after serving for three years as the INFUSE deputy director, where he helped private companies partner with DOE national labs and universities. “My time in the INFUSE program helped steer me toward ARPA-E by making me aware of the larger fusion ecosystem, as well as challenges needed to be addressed for fusion power plants,” he said. In his new position, Diallo will develop new programs aimed at accelerating fusion-produced electric power on the grid as well as oversee fusion projects that receive ARPA-E funding to ensure they have the necessary support to meet their milestones. ARPA-E funds high-risk and high-reward projects in the energy ecosystem that have the potential to improve America’s economy, prosperity, and environment.

“Ahmed successfully led and brought tremendous energy to the INFUSE program by building new private-public partnerships,” said Egemen Kolemen, a PPPL physicist and an associate professor in Princeton University’s Mechanical and Aerospace Engineering Department. “This along with his established leadership position in the fusion community and innovativeness makes him the ideal leader that ARPA-E needs.”

Diallo will remain at PPPL on a reduced schedule. He currently studies the edge of plasma, sometimes known as the fourth state of matter, within doughnut-shaped fusion facilities called “tokamaks.” He is looking forward to his new ARPA-E responsibilities. “I expect the position to be challenging, but very exciting,” he said. “It gives me the opportunity to engage with novel and high-risk ideas necessary to support the bold decadal vision for fusion the White House has laid out.”

Fostering public-private fusion partnerships

As INFUSE deputy director, Guttenfelder takes over a role previously held by Diallo and helps coordinate the DOE’s efforts to establish partnerships with private companies in the fusion industry. His responsibilities include helping coordinate the twice-yearly application and review process that private industry can respond to. Guttenfelder is also responsible for organizing the annual INFUSE workshop at which private companies, national laboratories, and universities share success stories from past awards and discuss new research opportunities.

“Walter’s broad perspective, insights, and commitment to the fusion energy goal make him an ideal person to help lead the INFUSE effort,” said Stanley Kaye, the Director of Research for PPPL’s National Spherical Torus Experiment-Upgrade (NSTX-U). “By working in the INFUSE program, he will be able to support the development of mutually beneficial partnerships between public entities like national laboratories and private industry to accomplish this goal in the shortest possible time.”

Guttenfelder will spend about 25% of his time on INFUSE tasks and spend the rest of his time as deputy director of the NSTX-U research group under Stanley Kaye. He is excited to be part of the INFUSE efforts. “We all want to see fusion energy become a reality,” he said. “The public-private partnerships enabled by the INFUSE program represent an important new rung on the ladder toward commercialization, enabling the growing fusion industry to take advantage of the foundational research that has historically been conducted through the federal program. For the longest time, I’ve been very happy to be knee-deep in the foundational research, but it’s exciting to me to observe and participate in these other areas of fusion development.”

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