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Raftopoulos takes on the challenge

As Chrzanowski "turns the page" after 39 years

Steve Raftopoulos is a lifelong “tinkerer” who has always found joy in building things and who loves his job at PPPL because it allows him to do just that. Now he’s bringing that sense of fun to a serious job as head of the team of engineers who help create the coils and other components of PPPL’s experiments.

Raftopoulos succeeds Jim Chrzanowski in two key positions as head of the Mechanical Design Branch of the Mechanical Engineering Division and as the lead engineer for PPPL’s coil engineering efforts. The changing of the guard comes after both helped oversee a major feat: The fabrication of the center stack, which was recently installed into the core of the Laboratory’s largest experimental vessel, the National Spherical Torus Experiment Upgrade (NSTX-U). This powerful magnet, devised by PPPL’s coil winding team, is a centerpiece of the upgrade.

But Raftopoulos isn’t resting on his laurels. “It’s done and it’s installed but I think the ultimate satisfaction will come when we put power to (the coils) and make a plasma,” he said. “We’ve put the new engine in the car but the car’s not ready to go around the track yet. That’s kind of where we are.” 

Raftopoulos succeeds Jim Chrzanowski who retired Oct. 31 after 39 years at PPPL. Chrzanowski said he was both relieved and delighted to see the center stack installed. “I’m really happy,” he said. “I really wanted to see this finished. I definitely wanted to deliver a finished component.”

The bundled magnetic coils in the center stack are like the powerful core of the NSTX-U apple. They create a magnetic field that helps contain the charged gas called plasma in a vacuum vessel inside the spherical container called a tokamak. At the same time, an ohmic heating coil in the center stack will inject a current into the plasma to help create a magnetic field and help heat the plasma to super-hot temperatures during experiments. The high temperature is required to create the conditions necessary to create fusion energy.

Like a doubles tennis team

Raftopoulos said he and Chrzanowski split many of the duties associated with overseeing the project. “It was like a doubles tennis team,” Raftopoulos said. “We didn’t say, ‘You handle this and you handle that.’ We filled in where the other person was too busy to cover or where we saw a need.”

In his new position as head of the Mechanical Design Branch, Raftopoulos oversees a team of 26 people, including 20 CAD designers and six engineers. He says he views his primary responsibility in the new position as helping his team members do their jobs. “My job is to help them to be as good as they can be and facilitate their work,” he said. “In a sense I work for them.”

Mike Williams, PPPL’s Associate Director for Engineering and Infrastructure, said Raftopoulos’s collaboration with Chrzanowski will serve him well in the new position. “They are big shoes to fill but Steve has a long distinguished career on his own and is definitely up to the challenge,” Williams said.

For Raftopoulos the new position is the latest challenge in a career that has been all about building the components that are vital to PPPL’s experiments. When he began in 1984 he worked on diagnostics for the Tokamak Fusion Test Reactor (TFTR). He also worked on the complex, twisted coils of the stellarator for NCSX, the National Compact Stellarator Experiment (now called QUASAR). “I’ve had a blast for 30 years,” Raftopoulos said. “It’s always interesting but when we’re building things it’s super exciting.”

Building the coils for NCSX was especially challenging. Raftopoulos was responsible for the metrology on the device, meaning he was in charge of making exact measurements.  He used computerized equipment to take 40,000 to 50,000 measurements of the coils dimensions to a thousandth of an inch. The project was never finished due to funding issues. But Raftopoulos said he and other members of the coil team derived some gratification in seeing the coils completed. “We at least got the satisfaction of building the most difficult coils that maybe anyone ever built,” he said.

The next challenge for Raftopoulos will be overseeing the installation of other components for the NSTX upgrade. His work on NSTX-U will continue even after it begins operating, Williams said. He and other engineers will be charged with ensuring it operates at optimal levels.

The “guru” of metrology

Williams said Raftopoulos put his expertise as the Lab’s chief metrologist or the “guru of metrology” to good use with NSTX-U. He will continue to use those skills as other components are installed, Williams added. 

The new head of the coil shop is known for his easy-going friendly manner, Williams noted. “He has great people skills,” he said.

He commutes at least an hour from his home in Cliffside Park, N.J. where he lives with his wife, Pera, a human resources professional, and two children Irene, 9, and John, 6.  Raftopoulos spends most of his time off with his kids. He also enjoys photography.

Passing along his knowledge

Raftopoulos credits Chrzanowski with passing along his years of knowledge by training him and other engineers. However, there will be no substitute for being able to stop into his former boss’s office to exchange ideas. “I would go in with one idea about how to solve a problem and I’d leave with a different idea about the direction,” he said.

Chrzanowski was sent off with a farewell luncheon at which many of his past and present colleagues discussed his contribution to the Laboratory. Phil Heitzenroeder, head of the Mechanical Engineering Division, noted that Chrzanowski scheduled his retirement perfectly just after the center stack was completed. He praised Chrzanowski’s work as “a very efficient manager.”

Chrzanowski was responsible for designing the coils and devising a method to create them. This involved a complex coil winding operation in which insulated tape was wound around 36 copper conductors. They were then bundled together through several applications of a vacuum pressure impregnation (VPI) process at very high temperatures of up to 100 degrees centigrade. The team then fabricated the ohmic heating coil that wraps around the bundle.

Hutch Neilson, the head of Advanced Projects, recalled that the National Compact Stellarator Experiment (now called QUASAR) needed coils that were designed to stabilize and maintain the plasma. “This was something so innovative and technologically revolutionary that it really had to be done in the Lab, so we gave the job to Jim, who assigned a dedicated coil team and got the job done,” he said.

In addition to NCSX, Chrzanowski was also involved in numerous projects, including creating the coils for the Advanced Toroidal Facility at Oak Ridge National Laboratory. He also worked on the recently commissioned trim coils for the Wendelstein 7-X stellarator in Germany, which is due to begin operating next year.

Many challenges

“There’ve been so many challenges over the years,” Chrzanowski said in an interview. “The modular coils for NCSX were the most difficult and also the most gratifying. There were 18 technicians on the job and they did a phenomenal job.”

Chrzanowski was quick give credit for the success of the NSTX-U coils to the team of designers, who “ran with” his ideas and the technicians and engineers who worked on the coils. “It’s a team effort no matter what you do,” he said. “You do a lot of brainstorming. My strengths are in fabrication – how to go ahead and do it.”

Turning the page

Having the center stack completed just before he left was perfect timing, Chrzanowski said. “It’s done, I’m done,” he said. “Turn the page. This place was terrific. I would do it all over again but it’s the right time for me.”

Chrzanowski’s immediate plan in retirement is to get ready for the holidays. An avid skier, he also plans to spend time skiing. Best of all, he’ll get to spend more time with his 4-year-old grandson Nathan, who lives in Philadelphia.  

He said he would miss working with colleagues who have come to feel almost like family members. “For me, it’s the people and the work,” he said.

“We’re working on a noble endeavor,” Raftopoulos said. “We’re doing something that will help humanity. It’s a great way to make a living.”

 

            

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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