Masaaki Yamada, a Distinguished Laboratory Research Fellow at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL), has won the 2015 James Clerk Maxwell Prize in Plasma Physics. The award from the American Physical Society (APS) Division of Plasma Physics recognized Yamada for "fundamental experimental studies of magnetic reconnection relevant to space, astrophysical and fusion plasmas, and for pioneering contributions to the field of laboratory plasma astrophysics."

Yamada will receive the award at the 57th annual meeting of the APS Division of Plasma Physics in Savannah, Georgia, in November, and will present a plenary talk to the session. "I am quite honored and pleased to be recognized," said Yamada, the principal investigator for PPPL's Magnetic Reconnection Experiment (MRX), the world's leading laboratory facility for studying reconnection—an astrophysical process that gives rise to solar flares, the northern lights, and geomagnetic storms.

Yamada previously won the APS's Award for Excellence in Plasma Physics Research in 2002 and received the Laboratory's Kaul Foundation Prize for Excellence in Plasma Physics Research and Technology the following year.

"Masaaki has accumulated a body of experimental work that has reshaped our understanding of the ubiquitous phenomenon of magnetic reconnection – overturning standard models, discovering new effects, defining new problems," said PPPL Director Stewart Prager. "The results have had huge impact from space physics to fusion plasma physics."

Yamada joined PPPL in 1973 as a postdoctoral fellow after earning a Ph.D. in physics from the University of Illinois. He previously received a bachelor's degree in applied physics and a master's degree in nuclear engineering from the University of Tokyo.

At PPPL, Yamada first worked on basic plasma physics experiments and fusion physics before pioneering research on the MRX, which he built in 1995. The device creates a prototypical magnetic reconnection, which takes place when lines of magnetic force separate and violently reconnect, unleashing large amounts of energy. Yamada has authored or coauthored more than 200 papers, and most recently he and co-workers identified the physical process by which magnetic reconnection converts magnetic energy into explosive particle energy.

Yamada's research bridges the worlds of fusion and plasma astrophysics. His management of the MRX project connects the behavior of magnetic field lines in magnetic fusion facilities with those on the surface of the sun and stars. "One of the nice things about this research is that we can learn a lot of solar and space science, as well as astrophysics, through the common language of plasma physics," he said.

Reconnection can have powerful consequences for both stars and tokamaks. In tokamaks, reconnection can cause disruptions that shut down fusion reactions. In the sun, reconnection can propel huge blobs of plasma into the solar system, creating disturbances that can disrupt satellites, obstruct cell phone service, and black out electricity grids when the plasma collides with the magnetic field that surrounds the Earth.

Yamada has held invited professorships at several international institutions, including the École Polytechnique Fédérale de Lausanne in Switzerland, Kyoto University and the University of Tokyo in Japan, and more than a dozen graduate students have received a Ph.D under his guidance. He remains modest about his achievements. "My winning the Maxwell Prize wasn't the result of my actions alone," he said. "I had a great deal of help from all of the other scientists who work on MRX and other plasma devices."

Yamada is the fourth PPPL researcher in the past 25 years to receive the Maxwell Prize. Former PPPL director Ron Davidson won the prize in 2008; Nat Fisch, director of the Princeton Program in Plasma Physics, received the honor in 2005; and Russell Kulsrud, a former head of PPPL's Theory Department, won it in 1993.