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Two PPPL physicists elected to receive prestigious honor

PPPL physicists David Gates and Charles Skinner have been named as American Physical Society fellows – a prestigious honor that is given to only one half of one percent of all APS members each year.

Gates, a principal research physicist and stellarator physics lead who has been at PPPL for 16 years, and Skinner, a principal research physicist at PPPL for 31 years whose work has focused on spectroscopy and plasma-wall interactions, will be honored at the APS Division of Plasma Physics meeting in Denver Nov. 11 to 15. The two bring the total number of APS fellows at PPPL to 51.

Gates said he was delighted at the recognition. “I think it’s a great honor,” he said. “It’s really nice to be recognized by such a distinguished group of your peers.”

Skinner was equally happy. “I’m thrilled, of course,” he said. “It means your accomplishments are recognized by your peers and that’s always very gratifying.”

Gates work on magnetic islands recognized

Gates was recognized primarily for his “innovation and leadership in the understanding and control” of magnetic islands, small bubble-like islands that appear in the hot charged gases or plasmas during magnetic fusion experiments that can cool the plasma and can cause a “density limit” that can prevent fusion reactors from producing as much power as possible.

His research into island physics and plasma control has applications in both tokamaks and stellarators, said Hutch Neilson, PPPL’s Advanced Projects director. “This is a recognition of Dave’s strong record of accomplishment as a physicist and the judgment of his peers of his impact on the field,” he said.

Gates joined PPPL in 1997 when PPPL’s National Spherical Torus (NSTX) experiment first began. He became involved in plasma control research and was quickly recognized as a leader in the field. His more recent work has focused on controlling and avoiding disruptive plasma instabilities. 

International collaborations on stellarators

Since 2009, Gates has been PPPL’s stellarator physics leader and has led the effort to build a new stellarator program through international collaborations. Despite differences in the challenges of controlling plasma in stellarators, Gates used his knowledge to collaborate with the Large Helical Device (LHD) project in Japan and Wendelstein 7-X project in Germany. He spent two summers doing research on LHD as a National Institute for Fusion Science visiting professor, where he supervised a team of early-career researchers.

“Dave’s work in island physics and plasma control and tokamaks makes him the ideal person to build a scientific bridge between tokamaks and stellarators because of his strong grasp of the overlapping physics issues, where the two concepts meet,” Neilson said.

After attending the University of Wisconsin-Madison as an undergraduate, Gates received his PhD from Columbia University in 1993. Before coming to PPPL, he was a research associate for the Culham Centre for Fusion Energy in the United Kingdom, working on the COMPASS-D and START experiments.

Gates said he enjoys coming to work each day at PPPL. “It’s a great job. I love my job,” he said. “There are very few jobs that allow you the intense freedom I get. I have ideas, I follow them through. Most of my days are different. I like to feel I’ve added to the field in a substantial way and that makes me feel useful.”

Skinner recognized for contributions to multiple areas

Skinner received the honor for contributions in multiple areas during his more than three-decade career in which he had three patents with Szymon Suckewer, now the director of Princeton University’s Plasma Science and Technology Program, and is first author of 21 invention disclosures for devices related to plasma physics.

“That’s the wonderful thing about Charles: He takes on an important topic and just does it,” said Masa Ono, head of PPPL’s NSTX Department. “That’s one reason he hasn’t been recognized previously because he wasn’t just focused on one thing.”

Skinner is a well-known expert on how the performance of plasmas used in magnetic fusion experiments is affected by the plasma’s interaction with the wall of the tokamak, known as plasma-wall interactions, which could interfere with obtaining optimal performance from the plasma in experiments.

Ground breaking research in spectroscopy

When he first arrived at PPPL in the 1980s, Skinner pioneered research into using plasma to create short X-ray lasers, a discovery that was announced at the APS Division of Plasma Physics meeting in 1984.

In the 1990s, Skinner began work on spectroscopy with ground-breaking research along with Suckewer into how spectroscopy can be used to measure the temperature of the highly charged particles known as ions in magnetic fusion experiments. “He was a very early pioneer of tokamak high temperature spectroscopy,” said Ono.

Skinner’s work in spectroscopy led him into research on how to measure and control the use of tritium, the radioactive fuel that was then used in PPPL’s Tokamak Fusion Test Reactor (TFTR). Skinner used spectroscopy to measure the amount of tritium that was being left behind on the walls of the reactor during the fusion experiments. His work on how tritium can be trapped in the graphite walls of a reactor led to the recognition that carbon could not be used as the material used for the walls of the international ITER fusion experiment in Cadarache, France, and other reactors. He also developed the use of lasers to remove the tritium from the tokamak walls. His work was recognized when he was asked to take part in the ITER design review and to serve on two panels and a working group related to ITER’s design.

An instrument to detect dust used in NSTX and worldwide

He and other researchers also found that tritium could be trapped in dust particles produced by the plasmas. Skinner developed an ultra-sensitive instrument that detects dust that is used in NSTX and in the Tore Supra tokamak in France.  More recently, he has been working with Bruce Koel, a professor of chemical and biological engineering at Princeton University who also maintains a laboratory at PPPL. Skinner is collaborating with Koel on efforts to understand  how lithium  can best be employed to form the walls of an experimental fusion device.

Skinner has also served as a mentor to numerous students at PPPL through the summer internship programs. More than 10 undergraduates worked with him on the dust detector, for example.

“I’ve had a diverse career in many different fields,” Skinner said. “Because of this diversity I have been able to find synergies between different fields and apply them to addressing issues in a novel way.”


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