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PPPL wins R&D 100 Award

A group of scientists, including a team working at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory, are being honored with a prestigious award for aiding the development of a device representing a key advance for fusion energy.

The editors of R&D Magazine have bestowed an “R&D 100” Award upon researchers for seminal theoretical work and two experimental studies that led to the creation of the “snowflake power divertor.” Dmitri Ryutov, a theorist at the Lawrence Livermore National Laboratory (LLNL), proposed the idea and led the theoretical effort. Four physicists who confirmed the validity of the approach through experiments on PPPL’s experimental fusion machine, the National Spherical Torus Experiment, were also honored for their efforts, including: Vlad Soukhanovskii (LLNL), who designed and led the experiments; Jon Menard, the NSTX program director (PPPL); Egemen Kolemen (PPPL); and Joon-Wook Ahn (Oak Ridge National Laboratory.) Soukhanovskii and Ahn are on long-term assignments at PPPL.

“This key invention and result could not have been realized without the contributions of the seminal theoretical work and the two experimental studies,” said Stewart Prager, the director of PPPL. Prager characterized the snowflake divertor as “a breakthrough for fusion.”

A major scientific and technological hurdle for the design of fusion energy machines is finding a way to distribute the hot plasma exhaust of hundreds of megawatts over a sufficiently large wall surface area. When heat escapes from the confined plasma, it can erode the machine's walls and contaminate the plasma.

The snowflake divertor offers the potential to solve this problem that occurs at the interface between the hot fusion plasma and the material walls surrounding it by reshaping the magnetic fields in such a way that excess heat is diverted. The device employs a previously unknown configuration of the divertor magnetic field whose shape is reminiscent of a snowflake. The resulting magnetic field lines spread the exhaust over a larger wall area and reduce the exhaust heat flux to manageable levels.

Experiments that employed a snowflake divertor on NSTX and on another experimental fusion facility known as TCV in Lausanne, Switzerland, confirmed that the divertor works. In a major upgrade project underway at PPPL, researchers will be installing a second snowflake divertor on the NSTX-U that will be used in future experiments.

Established by the editors of R&D Magazine, the annual R&D 100 Awards identify the 100 most significant, newly introduced research and development advances in multiple disciplines. The awards were established in 1963. Some of the winning products have included the flashcube (1965), the automated teller machine (1973), liquid crystal displays (1980), the anticancer drug Taxol (1993), and high definition television (1998).

U.S. Department of Energy
Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University.

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