Fusion Pioneer Wolfgang Stodiek Passes, Age 95

May 20, 2021

Wolfgang Stodiek, a pioneer in plasma physics and a researcher who helped lead the Princeton Plasma Physics Laboratory's early research on experimental devices called tokamaks, passed away at his family home in Bielefeld, Germany, on March 7. He was 95.

Among other accomplishments, Stodiek helped convert PPPL from fusion experiments on devices with twisted coils called stellarators to doughnut-shaped devices called tokamaks. He designed and oversaw, along with engineer Don Grove, the conversion of PPPL's C-Stellarator to the Symmetric Tokamak. He later led the Princeton Large Torus (PLT) experiment, whose research results eventually led PPPL to embark on its famous Tokamak Fusion Test Reactor (TFTR) experiment.

Although Stodiek retired in 1996 , he continued to come to work at PPPL two or three days a week until 2007 when the Stodieks returned to Germany to care for an ailing relative. A memorial service was held in Germany on March 18.

"This was a big turning point in the Laboratory's research program to switch from stellarators,which had been invented by the founder of the Laboratory (Lyman Spitzer), to tokamaks in1969," said Dale Meade, former deputy director of PPPL. "He was at the crossroads directing traffic."

Stodiek is survived by his wife of 45 years, Elsmarie Stodiek, whom he met when she was touring PPPL in the 1970s and they discovered they were from the same German town. Stodiek was born in Bielefeld in Northern Germany on May 22, 1925. He was drafted into the German Amy when he was 17 toward the end of World War II and was held briefly in a British prisoner of war camp.

Stodiek studied physics at Georg-August-Universität, a public research university in Göttingen. In 1950 he joined physicist Werner Heisenberg at the Max Planck Institute for Physics in Munich. Stodiek learned about fusion energy when he attended the famous Atoms for Peace Conference in 1958 where scientists worldwide first revealed fusion energy research and Princeton physicists displayed a model stellarator. The following year, his institute sent him to Princeton to learn more. Stodiek remained there for almost five decades.

Joins Project Matterhorn in 1959

When Stodiek first came to Project Matterhorn, (renamed the Princeton Plasma Physics Laboratory in 1962), he worked on the Model B-3 stellarator, along with other well-known early physicists at PPPL such as Robert Ellis Jr., father of chief engineer Bob Ellis. "He was one of my father's great friends," said Ellis, who recalled playing with his sister in the front yard when a strange man drove up to the house asking for his father. It was Wolfgang Stodiek, who had popped by to discuss plasma physics. "He was hugely passionate about his work in plasma physics," Ellis said.

When Russian physicists announced they had achieved super-hot plasma temperatures of 10 million degrees Celsius on an experimental device called a tokamak, Stodiek, an expert in x-ray diagnostics, was among many who were skeptical. But British scientists confirmed those results in a paper the following year and PPPL decided to focus on tokamaks. Stodiek was among those responsible in 1969 for converting the Model-C Stellarator into a tokamak.

"We have all lost a good friend and an excellent scientist," said physicist Ken Young, who began working with Stodiek in the 1960s. "His conversion of the stellarator to the ST tokamak was incredibly fast and he contributed hugely to the PLT. His understandings of all aspects of the tokamak devices was unmatched."

Ned Sauthoff, former director of the U.S. ITER Project Office, recalls meeting Stodiek in the control room of the Symmetric Tokamak (ST) when Sauthoff was a graduate student. Both Stodiek and Schweickhard "Schwick" von Goeler were Sauthoff's advisors. "Wolfgang was a real mentor and inspiration for me," Sauthoff said. "He was a leader in a generation of PPPL physicists who were deeply engaged in the mechanical and power systems. He could "diagnose" many a shot just by listening to the groaning of the systems."

Princeton Large Torus achievements

The Symmetric Tokamak confirmed that the tokamak was better able to confine the super-hot, electrically charged gas called a plasma than the early stellarators. This led to the construction of the Princeton Large Torus (PLT), which began operating in December 1975. Stodiek was head of the PLT experimental program in 1978 when the tokamak set a world record for achieving ion temperatures of 60 million degrees Centigrade using neutral beam heating.

"It was an exciting time," recalled Phil Efthimion, head of the Plasma Science & Technology Department who joined the PLT team in 1977 after completing his Ph.D. at Columbia University. "The machine had some spectacular results with neutral beam heating and RF (radio frequency) heating." "I'll always remember Wolfgang for his ability to quickly grasp the essence of any problem," said retired PPPL physicist Robert Kaita. "We used to joke that because of his "no frills" approach, all he needed was a multimeter to know how PLT was doing from the loop voltage. It didnÕt keep him, though, from offering kindness and encouragement to me as a young physicist that I'll never forget."

The PLT is also notable for employing x-ray diagnostics developed by a group that was led by von Goeler and included Sauthoff, Ken Hill and Manfred Bitter. Bitter was a lifelong friend of StodiekÕs who often visited him in Germany. "He was a very technical person and he knew everything about PLT," Bitter said of Stodiek. "Physics was his life." Stodiek is named as one of the inventors on a 2001 patent for an x-ray spectrometer along with Bitter, Ben Fraenkel, James Gorman, Ken Hill, Lane Roquemore, and von Goeler.

Stodiek was a good leader, Efthimion said. "I knew very little about tokamaks at all and I got there and was struck by all these powerhouse physicists that were on the machine, all very strong-willed, and Wolfgang managed the whole experiment," he recalled. "I think they put him there because he was very strong-willed and he could manage the group."

Michael Zarnstorff, PPPL chief scientist, recalled that Stodiek was "an elder statesman" at PPPL whom he enjoyed talking to about Stodiek's "skeptical view" of fusion energy." Efthimion agrees. "He was a bit of a pessimist but it didnÕt keep him from trying to do great things," he said.

Elsmarie Stodiek said her husband remained devoted to plasma physics and to PPPL. "When I first met him, the one thing he told me is 'My job is my hobby,'" she said. "He loved it and he was very happy there."